A cladistic analysis and taxonomic revision of the ...

Acta Zool. Fennica 213: 1–63 ISBN 951-9481-58-3 ISSN 0001-7299Helsinki 11 December 2001 © Finnish Zoological and Botanical Publishing Board 2001

A cladistic analysis and taxonomic revision ofthe Plesiosauria (Reptilia: Sauropterygia)

Frank Robin O’Keefe

Department of Anatomy, New York College of Osteopathic Medicine, OldWestbury, New York 11568, U.S.A

Received 13 February 2001, accepted 17 September 2001

O’Keefe F. R. 2001: A cladistic analysis and taxonomic revision of the Plesio-sauria (Reptilia: Sauropterygia). — Acta Zool. Fennica 213: 1–63.

The Plesiosauria (Reptilia: Sauropterygia) is a group of Mesozoic marine reptilesknown from abundant material, with specimens described from all continents. Thegroup originated very near the Triassic–Jurassic boundary and persisted to the end-Cretaceous mass extinction. This study describes the results of a specimen-basedcladistic study of the Plesiosauria, based on examination of 34 taxa scored for 166morphological characters. The Pliosauroidea is found to by polyphyletic due to theinclusion of the Polycotylidae; this second clade is instead a member of thePlesiosauroidea, and thus more closely related to elasmosaurs than to other ‘plio-saurs’. Characters of body proportion such as neck length and head size are verylabile, with the ‘pliosauromorph’ body plan evolving three times, while extremelylong necks evolved in two clades. Characters from the entire skeleton support theserelationships, although characters of the skull roof and palate are especially useful.Lastly, a new genus and species, Hauffiosaurus zanoni, is named based on Germanmaterial of Toarcian age.

Introduction

The term ‘plesiosaur’, meaning ‘near-lizard’, isnot an informative name from a modern per-spective. However, when Conybeare (1822)coined the term to describe fossils from theEnglish Lias little was known concerning anyextinct reptile. The realization that plesiosaurswere a completely extinct group was significantat a time when the occurrence of extinction itselfwas uncertain (Taylor 1997). These ‘near-rep-

tiles’ were named at a time when there was noneed, and no context, for a more specific term.

The Plesiosauria was a clade of Mesozoicmarine reptiles that evolved from stem-groupsauropterygians very near the Triassic–Jurassicboundary (reviewed in Rieppel 1997a, Rieppel2000). The clade diversified during the Jurassicand Cretaceous, only to join the dinosaurs ascasualties of the end-Cretaceous mass extinction(Romer 1966). Plesiosaurs were advanced overtheir ‘nothosaur’-grade forebearers in the evolu-

O’Keefe • ACTA ZOOL. FENNICA No. 2132

tion of wing-shaped fore and hind flippers thatgenerated thrust via lift as well as drag (Godfrey1984, Lingham-Soliar 2000). Plesiosaurs wereunusual among marine reptiles because theyused no axial flexure when generating thrust(Storrs 1993); plesiosaurs are unique amongaquatic tetrapods in the elaboration of both foreand hind limbs for lift-based thrust generation.The evolution of this novel locomotor appara-tus, and the pelagic lifestyle it allowed, led torapid diversification and the evolution of differ-ent morphotypes linked to prey size (Massare1988, O’Keefe 2002).

Plesiosaur taxonomy

The taxonomy of the Infra-order Plesiosauria(de Blainville 1835) suffers from the compara-tive taxonomic chaos of the Victorian era. How-ever, Andrews (1910, 1913), Welles (1943,1952), Tarlo (1960), Persson (1963), and Brown(1981) have all revised plesiosaur taxonomy.All formalized the plesiosauromorph/pliosauro-morph dichotomy in their classifications, fol-lowing the lead of earlier workers such as Owen(1841), Lydekker (1889b), and Seeley (1892).Until the work of Carpenter in 1997, Williston(1925) was the only worker to break with theaccepted, morphotype-based taxonomy. Plesio-saur relationships have been considered recentlyby Brown and Cruickshank (1994). These work-ers also retain the traditional dichotomy. Thecurrent taxonomy is listed below, based onTarlo (1960), Persson (1963), Brown (1981,1993), and Brown and Cruickshank (1994).

Diapsida Osborn, 1903Sauropterygia Owen, 1860

Infra-Order Plesiosauria de Blainville, 1835Superfamily Plesiosauroidea Welles, 1943

Family Plesiosauridae Gray, 1825Family Elasmosauridae Cope, 1870Family Cryptoclididae Williston, 1925Family Cimoliasauridae Delair, 1959

Superfamily Pliosauroidea Welles, 1943Family Pliosauridae Seeley, 1874Family Rhomaleosauridae Kuhn, 1961Family Polycotylidae Williston, 1908

Early taxonomies classified plesiosaurs withrespect to two body proportion morphotypes(classifications reviewed in Welles 1943). Thesemorphotypes were the long-necked, small-headed‘plesiosaurs’ (here termed plesiosauromorphs)and the large-headed, short-necked ‘pliosaurs’(here termed pliosauromorphs). However, as ear-ly as 1907 Williston suggested that the short neckin ‘pliosaurs’ might have evolved at least twice.The validity of the pliosauromorph/plesiosauro-morph dichotomy was challenged more recentlyby Carpenter (1997), and preliminary cladisticanalyses by Bardet (1998) and Druckenmiller(1998) challenged the monophyly of the Super-family Pliosauroidea as traditionally defined. Thisstudy is a specimen-based analysis whose goal isthe elucidation of the phylogeny of the Plesiosau-ria. The terminal taxa in this analysis are genera,as higher-level relationships are the primary goal.The principal finding is the polyphyly of thePliosauroidea as traditionally defined, by inclu-sion of the Polycotylidae. Placement of this fami-ly in the Plesiosauroidea also results in somereorganization of that taxon.

Phylogenetic context

The Sauropterygia is a clade of basal diapsids,more closely related to lepidosaurs than archo-saurs but near this basal dichotomy (see Rieppel& Reisz 1999 for a review). Some recent workhas indicated that Testudines is the sister groupof Sauropterygia, although this work is contro-versial (Rieppel & deBraga 1996, Lee 1997, deBraga & Rieppel 1997, Rieppel & Reisz 1999).The comparative anatomy and phylogeny ofTriassic sauropterygians have been the subjectof intense study over the last decade. Storrs(1991) published a cladogram of stem-groupsauropterygians in the context of his redescrip-tion of Corosaurus, at that time the only Triassicsauropterygian known from the New World.Storrs also reviewed stem-group sauroptery-gians. This phylogeny underwent exhaustive re-vision by Rieppel, who engaged in a program ofredescription, taxonomic revision, and biogeog-raphy of all stem-group sauropterygians (re-viewed in Rieppel 1999, Rieppel 2000, Rieppel

ACTA ZOOL. FENNICA No. 213 • A cladistic analysis and taxonomic revision of the Plesiosauria 3

1994a, 1998, Rieppel & Wild 1996, and espe-cially Rieppel 2000 are good entrance points toRieppel’s literature on the group). Field work byRieppel, Storrs, and others also yielded remainsof a new sauropterygian from Nevada (Sander etal. 1997). This new genus (Augustasaurus) is apistosaurid, and is significant because pistosau-rids are thought to be the sister group to thePlesiosauria (Sues 1987). The only other knownpistosaurid is Pistosaurus from the Triassic ofGermany, described by Meyer (1839) and Ed-inger (1935) from two skulls, the more completeof which is now lost. Rieppel (1994a) rede-scribed the remaining skull, while Sues (1987)described the postcranium of Pistosaurus indetail.

The cladogram topologies obtained by Riep-pel varied as his research program evolved.More definitive versions from later publicationssuch as Rieppel (1998, 1999, 2000) agree on thebroad outline of sauropterygian phylogeny. InRieppel’s topology, placodonts are the firstbranch within the clade Sauropterygia, makingthem the outgroup to all other ‘nothosaur’-gradesauropterygians plus the Plesiosauria (clade Eo-sauropterygia). Three subclades are found with-in this group, one comprised of pachypleuro-saurs such as Dactylosaurus and Neusticosaurus(clade Pachypleurosauroidea). A second clade iscomposed of the ‘nothosaurs’ Simosaurus, Not-hosaurus, and related taxa (clade Nothosauria),and a third contains the Plesiosauria and plesio-saur-like ‘nothosaurs’ (clade Pistosauroidea; no-menclature from Rieppel 1998, Rieppel 1999,2000). Clade Pistosauroidea contains the generaCymatosaurus, Corosaurus, Pistosaurus, andthe closely related Augustasaurus. In the follow-ing discussion, stem-group eosauropterygians(i.e., eosauropterygians minus the Plesiosauria)are refered to using the colloquial terms ‘notho-saur’ or ‘‘nothosaur’-grade taxa’. When the termnothosaur appears without quotes, it refers onlyto the monophyletic clade Nothosauria.

Anatomical background

Some introductory comments concerning theanatomy of plesiosaurs and their sauropterygian

antecedents are necessary. This section discuss-es only areas of variability, especially concern-ing the skull and limb girdles. Specific charac-ters and their states are discussed in Appendix 1.

Cranial anatomy

No comprehensive review of the plesiosaurskull has been attempted since the work ofAndrews (1910, 1913). Brown (1981, 1993),and Brown and Cruickshank (1994) discussedthe skull roof of Cryptoclidus and related gen-era, while the cranial anatomy of rhomaleosau-rids has been treated recently by Cruickshank(1994a, 1994b, 1997). Carpenter (1996) re-viewed the cranial anatomy of the polycotylids.The primitive taxa Plesiosaurus (Storrs 1997)and Thalassiodracon (Storrs & Taylor 1996)have also been redescribed recently, as has theprimitive Eurycleidus (Cruickshank 1994b).

The sauropterygian skull roof is remarkablein several ways. The first and most obvious isthe pattern of temporal fenestration, where thepresence of the upper temporal fenestra and thelack of a lower temporal fenestra led Williston(1925) to classify the sauropterygians within his‘Synaptosauria’. Colbert amended this name to‘Euryapsida’, a term retained by Romer (1956,1966). Like many higher-level taxon names,‘Euryapsida’ has fallen into disuse due to a lackof certainty concerning its monophyly, althoughMerck (1997) has performed a cladistic analysison all ‘euryapsids’ and believes them to bemonophyletic.

The condition of the Permian plesiomorphicdiapsid Araeoscelis, described in detail byVaughn (1955), is an acceptable model fromwhich to derive the sauropterygian skull roof.All sauropterygians retain only the upper tempo-ral fenestra, as does Araeoscelis. The uppertemporal fenestra becomes greatly enlarged inthe Sauropterygia, concurrent with a narrowingof the parietal skull table, creating a large sur-face for attachment of the jaw adductor muscu-lature (Rieppel 1994a). The trends of enlarge-ment of the upper temporal fenestra and narrow-ing of the parietals become extreme in plesio-saurs; in all plesiosaurs, the posterior parietals


form a sharply keeled sagittal crest, and the pinealforamen moves far forward to a position near theparietal-frontal suture. Both of these charactersare present in Pistosaurus, the most plesiosaur-like of the basal sauropterygians. Also present inPistosaurus and all plesiosaurs is the ‘squamosalarch’, or the meeting at the postero-dorsal marginof the skull of median processes of the squamos-als. This median squamosal suture excludes theparietals from the occiput. The pistosaurid genusCymatosaurus is intermediate between basal‘nothosaurs’ and plesiosaurs in having a verynarrow exposure of the parietal on the occiput(Rieppel & Werneburg 1998).

In Araeoscelis, paired nasal bones contactthe external nares and meet in a long midlinesuture, anterior to the paired frontals that alsomeet broadly on the midline. All three clades ofsauropterygians contain members where the na-sal midline suture is lost due to the formation ofa midline frontal-premaxilla suture. Pistosaurushas this suture, and is further derived in havingvery small nasals that do not contact the externalnares (Edinger 1935). Rieppel (1994a) could notdetermine whether nasals were present in theremaining skull of this taxon. The presence orabsence of nasals in plesiosaurs has always beendebated, with Andrews (1910) identifying themin some pliosaurs. More recently, Storrs hasmaintained that all plesiosaurs lack nasals(Storrs 1991), and his skull roof reconstructionsof the very primitive plesiosaurs Plesiosaurus(Storrs 1997) and Thalassiodracon (Storrs &Taylor 1996) omit nasals. However, nasals arein fact present in Thalassiodracon as well as inall more derived members of the Pliosauroidea(see below). The nasal is lost in all Plesiosauroi-dea, including Plesiosaurus. When present inplesiosaurs, the nasals are always separated byposterior processes of the premaxillae, as is thecase in Cymatosaurus. In many plesiosaurs thepremaxillary processes extend back to contactthe parietals, separating the frontals on the skullsurface, although the frontals may continue tohave a midline suture beneath the premaxillae(Andrews 1911b).

Araeoscelis is plesiomorphic in the retentionof the lacrimal, stretching from orbit to externalnaris. The lacrimal is lost in all sauropterygians(Rieppel 1997b), including all plesiosaurs (con-

tra Andrews 1913, and Taylor & Cruickshank1993). The quadratojugal, also present in Araeo-scelis and most basal sauropterygians, is alsolost in the Pistosauroidea and all plesiosaurs.The position and relations of the jugal is varia-ble in sauropterygians, but Pistosaurus andmany plesiosaurs possess a prominent suturebetween the maxilla and squamosal. This sutureexcludes the jugal from the ventral skull margin;in Simosaurus and other ‘nothosaur’-grade sau-ropterygians the jugal enters the ventral skullmargin (Rieppel 1994a). The jugal is taxonomi-cally important in plesiosaurs, and the configu-ration of the other circum-orbital bones in gen-eral is also diagnostic.

The posterior palate and basicranium arediagnostic in plesiosaurs, but this area is highlyconserved in more basal sauropterygians, and isoften obscured by other skull elements. In all‘nothosaur’-grade sauropterygians, the ptery-goids meet in a median suture that extendscaudally almost to the occipital condyle, form-ing a solid plate of bone beneath the basicrani-um (Storrs 1991, Rieppel 1997b). This ptery-goid median suture closes off both the anteriorand posterior interpterygoid vacuities, the pres-ence of which in Araeoscelis exposes the dermalossification of the parasphenoid as well as theendochondral ossifications of the braincase (i.ebasisphenoid and basioccipital). Araeoscelis isprimitive in this regard, very similar to theCarboniferous diapsid Petrolacosaurus (Reisz1981). In Pistosaurus, the posterior interptery-goid vacuity reappears, again exposing the ven-tral surface of the braincase. The morphology ofthe braincase is unknown in Pistosaurus. Inprimitive plesiosaurs, the palate opens further toreveal the anterior parasphenoid and the brain-case. These structures show a remarkable simi-larity to the condition in Araeoscelis. The reap-pearance of the anterior and posterior interptery-goid vacuities in plesiosaurs is correlated with atrend of reduced ossification in the skeletongenerally, a common feature of many aquatictetrapods (Storrs 1991, Romer 1956). Ossifica-tion of the more ventral structures of the brain-case is also reduced in plesiosaurs, to the pointthat the dorsum sellae and sella turcica are nolonger identifiable in derived pliosauroids.These structures are prominent and well-ossified


in Nothosaurus (Rieppel 1994b), and are presentbut less well-ossified in the pistosauroid Cyma-tosaurus (Rieppel & Werneburg 1998). Cymato-saurus also possesses a deep, narrow notch inthe posterior border of the clivus, a feature itshares with all plesiosaurs in which the dorsumsellae and clivus are ossified (Fig. 1).

Postcranial anatomy

Romer’s (1956: pp. 298–332) introduction tothe anatomy of the reptilian limb girdles illus-trates the general conditions of the pectoral andpelvic girdles in primitive amniotes. Again,Araeoscelis is a plesiomorphic diapsid that maybe used as a model from which to derive thesauropterygian conditions. In the pelvic girdle ofAraeoscelis, the pubis and ischium form a solidplate without a thyroid fenestra, surmounteddorsally by the ilium (Vaughn 1955). The obtu-rator foramen is primitively present in the pubis.All sauropterygians have a large thyroid fe-nestra. The obturator foramen is present in allsauropterygians except plesiosaurs, the pistosau-roid Cymatosaurus, and the true nothosaur Lari-osaurus. Girdle ossification in plesiosaurs isslow and varies intra-specifically to some degree(Brown 1981), leading Brown to question thetaxonomic utility of characters relating to girdleshape. The plesiosaur pelvic girdle is apomor-phic in the great reduction of the ilium, the lossof contact between ilium and pubis, and theconcomitant absence of the ilium from theacetabulum. In all plesiosaurs, the ilium is anarrow rod of bone running from the ischium to

a reduced sacrum composed of one to threesacral ribs.

The pectoral girdle is more complex andmuch more variable within the Sauropterygia.All sauropterygians have one coracoid ossifica-tion rather than the primitive two present inAraeoscelis; the cleithrum is also absent in allsauropterygians (Rieppel 1997b). Furthermore,there is a broad trend of reduction in the dorsalstructures of the pectoral girdle and elaborationof them ventrally. In placodonts the shouldergirdle is still relatively plesiomorphic. The bladeof the scapula is prominent laterally, and thecoracoids do not meet on the ventral midline.However, the dermal elements of the shouldergirdle (clavicles and interclavicle) are large androbust, and are primarily ventral structures. In‘nothosaur’-grade sauropterygians, the claviclesremain large and, unlike placodonts, have aprominent medial suture and concomitant reduc-tion of the interclavicle. Also in contrast toplacodonts, ‘nothosaur’-grade sauropterygianspossess a ventral median suture of the coracoids.The coracoids are enlarged relative to those ofplacodonts and are distinctively narrowed or‘waisted’ near their centers (Storrs 1991: p. 75).The coracoids are plate-like and not waisted inthe pistosauroid Corosaurus. In Augustasaurusthe coracoids are large ventral plates similar tothose in plesiosaurs (Sander et al. 1997; author’spers. obs.). The coracoid foramen is also lost inCorosaurus and Augustasaurus, a trait thesetaxa share with plesiosaurs.

The pectoral girdle in plesiosaurs is charac-terized by reduction of the scapular blade(Romer 1956) and a great ventral elaboration of

Fig. 1. Eurycleidus arcu-atus braincase, OUMJ.28585. Length of frag-ment 4.5 cm.


the scapulae. The dorsal blade of the scapula issituated dorsal to the glenoid in ‘nothosaur’-grade sauropterygians, but is anterior to theglenoid in all plesiosaurs (Kebang & Rieppel1998). The ventral processes of the scapulaeangle anteriorly toward the midline and meet ina midline suture in some derived taxa. Thisventral elaboration of the scapulae comes at theexpense of the clavicles and interclavicle, whichare reduced and near the midline in plesiosaurs.The coracoids are also greatly elaborated inplesiosaurs, forming large plate-like extensionsposteriorly with a long midline suture betweenthem. The coracoids may also send processesforward to meet either the clavicles or scapulaeon the midline, dividing the ventral space en-closed by the pectoral girdle into two pectoralfenestrae (for example Welles 1962, Storrs1997). This median pectoral bar is slow to ossify(Brown 1981), as is the comparable medianpelvic bar (present in Plesiosaurus, Storrs 1997,and some elasmosaurs, Welles 1962). The ag-gregate effect of changes in the pelvic andpectoral girdles is the formation of two large,

ventral plates of bone vaguely reminiscent of aturtle plastron. The short space between theanterior and posterior girdles was filled withclosely spaced gastralia. The ventral plates werepresumably the areas of attachment for largelocomotor muscles (Williston 1914).

The limbs of plesiosaurs are highly specializedhydrofoils. The modifications of propodials andepipodials are complex in sauropterygians, espe-cially across the pistosaurid/plesiosaur transitionand within basal plesiosaurs. In general terms, thepropodials tend to lose obvious processes for mus-cle attachment and become short and stout (Storrs1997, Romer 1956). A pronounced bend caudad inthe shaft of the humerus is characteristic of ‘notho-saur’-grade taxa and some very primitive plesio-saurs, but the shaft is straight in all derived plesio-saurs (Storrs 1997). Both the ectepicondylar andentepicondylar foramina are lost in all plesiosaurs;in ‘nothosaur’-grade sauropterygians the ectepi-condylar foramen is often reduced to a groove ornotch, and both features are variably present inbasal sauropterygians. However, the pistosauroidsCorosaurus and Cymatosaurus possess both open-

Table 1. Repositories and abbreviations for sauropterygian material referenced in this report.————————————————————————————————————————————————

Repository Abbrev. Location————————————————————————————————————————————————01 American Museum of Natural History AMNH New York, New York, USA02 The Natural History Museum BMNH London, UK03 Banque de la República de Villa de Leyva BRI Bogota, Columbia04 Bristol Museum and Art Gallery BRSMG Bristol, UK05 Sedgwick Museum CAMSM Cambridge, UK06 Sternberg Museum of Natural History FHSM Fort Hayes, Kansas, USA07 Field Museum of Natural History FMNH Chicago, Illinois, USA08 Institut und Museum für Geologie und Paläontologie GPIT Tübingen, Germany09 Urwelt Museum Hauff Hauff Holzmaden, Germany10 Kansas Museum of Natural History KUVP Lawrence, Kansas, USA11 Leicester City Museum LEICT Leicester, UK12 Manchester Museum MAN UM Manchester, UK13 Geologisch-Paläontologisches Museum der Universität Münster Münster Münster, Germany14 Museum of Comparative Zoology, Harvard University MCZ Cambridge, Massachusetts, USA15 Museum of the Rockies MOR Bozeman, Montana, USA16 National Museum of Wales NMW Cardiff, Wales17 Oxford University Museum of Natural History OXFUM Oxford, UK18 Peterborough Museum and Art Gallery PETMG Peterborough, UK19 Strecker Museum, Baylor University SM Waco, Texas, USA20 Staatliches Museum für Naturkunde, Stuttgart SMNS Stuttgart, Germany21 Southern Methodist University Museum of Paleontology SMUSMP Dallas, Texas, USA22 Texas Technical Institute TTVP Lubbock, Texas, USA23 University of California Museum of Paleontology UCMP Berkeley, California, USA24 Smithsonian Institution USNM Washington, D.C., USA25 University of Wyoming UW Laramie, Wyoming, USA26 Yorkshire Museum YORYM York, UK27 Yale-Peabody Museum YPM New Haven, Connecticut, USA————————————————————————————————————————————————


ings, whereas the pistosaurids Pistosaurus andAugustasaurus lack both openings, another condi-tion these taxa share with plesiosaurs. The epipodi-als resemble the propodials in becoming relativelyshort and broad in basal eosauropterygians. Themanus and pes are characterized by hyperphalangyin all plesiosaurs. The phalangeal formulas in thepistosaurids are unknown. The hypophalangy hy-pothesized by Sander et al. (1997) in Augustasau-rus is probably an artifact of preservation (O.Rieppel pers. com.).

Materials and methods

The plesiosaur material discussed here is held in27 institutions in the United States, South Ameri-ca, and Europe (listed in Table 1). Material in 24of these institutions was examined personally;material from the other three institutions (Geolo-gisch-Paläontologisches Museum der UniversitätMünster, Museum of the Rockies, Banque de laRepública de Villa de Leyva) was scored fromthe literature. The three outgroup and 31 ingrouptaxa considered in this report are listed below.Each genus is presented with primary and morerecent references, holotype and specimen number,referred material, and other remarks. Charactersused in the phylogenetic analysis are discussed inthe second part of the Materials and Methodssection, and listed in Appendix 1. The data matrixis listed in Appendix 2.

Description of Hauffiosaurus gen. n. andHauffiosaurus zanoni sp. n.

Hauffiosaurus gen. n.

DIAGNOSIS: as for species.

ETYMOLOGY: The genus name refers to the Urwelt-Muse-um Hauff, the institution in Holzmaden, Germany wherethe type species is housed.TYPE SPECIES: Hauffiosaurus zanoni

Hauffiosaurus zanoni sp. n.

DIAGNOSIS: A plesiomorphic member of cladePliosauridae possessing the following autapo-

morphies: seven premaxillary teeth; ectoptery-goid boss contacts jugal exclusively; propodialsvery long.

TYPE MATERIAL: — Holotype: Hauff museum uncata-logued, a complete skeleton in the Hauff Museum, Holz-maden, Germany. Figs. 2 and 3.ETYMOLOGY: The species name zanoni refers to the late R.T. Zanon, who first realized this specimen represented anew genus (R. T. Zanon unpubl.).REFERRED MATERIAL: none.TYPE LOCALITY: Posidonien-Schiefer, Holzmaden, Germany.AGE: Toarcian.

DESCRIPTION: The specimen here designatedHauffiosaurus zanoni (Hauff museum uncata-logued) is a complete plesiosaur skeleton pre-served in ventral view, found in the Posidonien-Schiefer of Holzmaden, Germany (Toarcian).The skeleton is approximately 2.5 m long, anddisplays an interesting mix of plesiomorphic,derived, and apomorphic features. For a com-plete listing of character states in this taxon, seeAppendix 2.

The skull is preserved in palatal view(Figs. 2 and 3), with the mandibles crushed anddisplaced to one side. The snout and mandibular

Fig. 2. Hauffiosaurus zanoni n.gen n.sp palate,Hauff uncat. Length of skull 43 cm.


symphysis are both very long, indicating that thespecimen is not a rhomaleosaur, and is instead amember of the Pliosauridae. On the palate, thevomers extend beyond the posterior margin ofthe internal nares and meet the pterygoids in awide, interdigitating suture very similar to thatin Peloneustes. This suture lacks the medianextension on the midline characteristic of Mac-roplata. The Hauff taxon also possess a promi-nent ectopterygoid boss unlike Macroplata butlike Peloneustes, although the boss articulateslaterally with the jugal only rather than both thejugal and squamosal as in Peloneustes. There isno anterior interpterygoid vacuity. The paras-phenoid is exposed prominently on the palate

surface anterior to the posterior interpterygoidvacuity. The basisphenoid is poorly ossified, asin Peloneustes and all other pliosaurids exceptMacroplata. The pterygoids meet behind theposterior interpterygoid vacuity, and there isevidence of a lateral flange around the vacuitiessimilar to that in Peloneustes and Kronosaurus.However, the sigmoid shape and rolled lateralmargin of the quadrate flange of the pterygoidare absent in the Hauff taxon, as in Macroplatabut unlike all more derived pliosaurids. Thereare seven teeth in each premaxilla, an autapo-morphy (Peloneustes has six teeth in the pre-maxilla). In sum, the palate of the Hauff speci-men shows a mixture of primitive and derived

Fig. 3. Photographs ofthe holotype of Hauffio-saurus zanoni. Top, de-tail of skull and mandi-bles. Compare to Fig. 2.Length of skull 43 cm.Bottom, entire skeletonas preserved. Note that‘body outline’ was carvedduring preparation; nosoft tissue is preservedwith the specimen.


features, and seems to be intermediate betweenthe plesiomorphic Macroplata and more derivedPeloneustes. The position of the Hauff taxon onthe cladogram reflects this impression.

The most remarkable aspect of the postcrani-um is the extreme length of the propodials. Thehumerus is 32 cm long, while the femur is 35 cmlong. Both propodials are longer than any oftheir associated girdle bones, a unique featureamong plesiosaurs and an autapomorphy of thistaxon. The postcranium in general displays rela-tively small girdles, high aspect-ratio fins, and aneck that is primitive in length and vertebralnumber. Hauffiosaurus zanoni is a stratigraphi-cally early (Toarcian) and morphologically inter-mediate member of the Pliosauridae, and pos-sesses several autapomorphies in the skull andpostcranium.

Included taxa

Outgroup taxa

Three taxa were chosen as outgroups for thisanalysis. They are the nothosaur Simosaurus, thepistosauroid Cymatosaurus, and the family Pis-tosauridae. The family Pistosauridae comprisesthe genera Pistosaurus and Augustasaurus.These two taxa were scored together becausethey are closely related, and because the materialfor the two genera is complementary. The postc-ranium of Augustasaurus is articulated and well-preserved, unlike that of Pistosaurus, which hasled to some doubt in the postcranial reconstruc-tion of the later taxon (Sues 1987). The skull ofAugustasaurus is extant, and a description is inpress a this time (O. Rieppel pers. com.), whilethat of Pistosaurus was described in detail byEdinger (1935; skull now lost).

GENUS: Simosaurus Meyer, 1842

TYPE SPECIES: Simosaurus gaillardoti Meyer, 1842.TYPE MATERIAL: — Holotype: lost. — Neotype: SMNS16700 (Rieppel 1994a).TYPE LOCALITY: Upper Muschelkalk, Lunéville, France.AGE: Ladinian.REFERRED MATERIAL: various, one known species.REMARKS: Taxonomy and referred material reviewed inRieppel 1994a.

GENUS: Cymatosaurus v. Fritsch, 1894

TYPE SPECIES: Cymatosaurus fridericianus v. Fritsch, 1894.TYPE MATERIAL: — Holotype: Institut für Geowissen-schaften, Martin-Luther Universität, Halle/Saale, uncata-logued.TYPE LOCALITY: Lower Muschelkalk, Halle/Saale, Germany.AGE: Ladinian.REFERRED MATERIAL: various, at least four known species.REMARKS: Taxonomy and referred material reviewed inRieppel (1997b, 1998b), and Rieppel and Hagdorn (1997).

FAMILY: Pistosauridae Zittel, 1887

TYPE SPECIES: Pistosaurus longaevus Meyer, 1839.TYPE MATERIAL: — Holotype: Oberfränkisches Erdges-chichtliches Museum, Bayreuth, uncatalogued.TYPE LOCALITY: Upper Muschelkalk, Bayreuth, Germany.AGE: Late Anisian.REFERRED MATERIAL: various, possibly two species.REMARKS: Taxonomy, referred material, and postcraniumreviewed in Sues (1987). Cranium described by Edinger(1935), and Rieppel (1994a).

TYPE SPECIES: Augustasaurus hagdorni Sander, Rieppeland Bucher, 1997.TYPE MATERIAL: — Holotype: FMNH PR 1974.TYPE LOCALITY: Favret Formation, Pershing County, Nevada.AGE: Late Anisian.REFERRED MATERIAL: none.REMARKS: Augustasaurus is one of two nothosaur-gradesauropterygians from North America; the other is Coro-saurus. The skull of Augustasaurus is currently beingdescribed by O. Rieppel, M. Sander, and G. Storrs.

Ingroup taxa

Thirty-one plesiosaur genera were coded forinclusion in the phylogenetic data matrix. Twoof these taxa are unnamed at present; these taxaare referred to by specimen number. Several ofthe genera included here contain more than onespecies. The common genus Plesiosaurus prob-ably contains three valid species, while Mu-raenosaurus contains at least two valid species.Because genus-level and higher relationshipsare the primary goal of this analysis, polytypicgenera are treated as terminal taxa here. Howev-er, species level diagnoses are given in theSystematic Paleontology section where appro-priate. Another complication is that the genusRhomaleosaurus is paraphyletic (see Results).The species of Rhomaleosaurus included here


are referenced using both genus and speciesnames. The listings of referred material belowmention only material used in this study; com-plete lists of referred material can generally befound in references cited in the remarks for eachtaxon. The sampling of plesiosaur taxa in thisstudy is not exhaustive. Several Rhomaleosau-rus species are omitted, as are several elasmo-saur genera and some other poorly-known taxa.All known clades are well-represented, howev-er, and the omission of some ingroup taxa fromsome clades should not influence the resultsreported here. The genus Rhomaleosaurus andthe Elasmosauridae are both in need of taxo-nomic revision. Lastly, exhaustive synonomiesare not given for each taxon. Some remarks on

the taxonomic history of most genera are givenin the remarks section, along with referenceswhere synonomies can be found for those taxa.

GENUS: Thalassiodracon Storrs & Taylor, 1996

TYPE SPECIES: Thalassiodracon hawkinsi (Owen, 1838).TYPE MATERIAL: — Holotype: BMNH 2018.TYPE LOCALITY: Street, Somerset, England.AGE: Rhaetian-Hettangian boundary.REFERRED MATERIAL: BMNH 14550, 2020, R.1336 (juv.)CAMSM J.46986, OUM J.10337, MM L. 9767.REMARKS: Fig. 4. Storrs and Taylor (1996) created thisgenus name for the taxon ‘Plesiosaurus’ hawkinsi (Owen1838), a stratigraphically early and morphologically prim-itive plesiosaur. These authors list other material referableto this taxon, and describe the skull in some detail. Aredescription of the postcranium is necessary.

GENUS: Eurycleidus Andrews, 1922

TYPE SPECIES: Eurycleidus arcuatus (Owen, 1840).TYPE MATERIAL: — Holotype: BMNH 2030 (see Cruick-shank 1994b).TYPE LOCALITY: Lyme Regis, Dorset, England.AGE: Hettangian- Lower Sinemurian.REFERRED MATERIAL: OUM J.28585, SMNS 16812.REMARKS: Fig. 1. Cruickshank (1994b) redescribes this

Fig. 4. Thalassiodracon hawkinsi skull roof, OUMJ.10337. Abbreviations used in the following figuresare as follows: aipv, anterior interpterygoid vacuity;ang, angular; cor, coranoid; d, dentary; ect, ectop-terygoid; f, frontal; j, jugal; m, maxilla; n, nasal; p,parietal; pal, palatine; pf, prefrontal; pipv, posteriorinterpterygoid vacuity; pm, premaxilla; po, postor-bital; pof, postfrontal; preart, prearticular; pt, ptery-goid; q, quadrate; sof, suborbital fenestra; spl, sple-nial; sq, squamosal; surang, surangular; v, vomer.Length of skull 18 cm.

Fig. 5. Plesiosaurus dolichodeirus skull roof, BMNH39490. Length of skull 23 cm.


genus and refers other material to it. I refer the Germanspecimen to this taxon based on similarities in the basic-ranium; however this referral is provisional until theGerman material (a complete skeleton) can be describedin more detail. Fig. 1.

GENUS: Plesiosaurus De la Beche & Conybeare,1821

TYPE SPECIES: Plesiosaurus dolichodeirus, Conybeare 1824.TYPE MATERIAL: — Holotype: BMNH 22656.TYPE LOCALITY: Lyme Regis, Dorset, England.AGE: Uppermost Sinemurian.REFERRED MATERIAL: P. dolichodeirus: BMNH 39490,41101, 36183, R.1756, OXFUM J.10304; P. brachyp-terygius: SMNS 51143, Hauff uncatalogued, GPIT 477/1/1; P. guiliemiimperatoris: SMNS 51015.REMARKS: Figs. 5 and 6. Andrews (1896) gives the firstdetailed account of the structure of the palate in this taxon.The genus is reviewed exhaustively in Storrs (1997).Storrs discusses other material also referable to this taxon,and advances the hypothesis that the many nominal speciesin this common and widespread genus are representative ofperhaps three valid species. My interpretation differssomewhat; P. brachypterygius lacks the lunate ulna char-acteristic of P. dolichodeirus, and may be a valid species

as well. I agree with Storrs that P. guilemiimperatoris is avalid species; that author also states that material fromFrance may represent another valid species. The Frenchmaterial was not examined in the course of this study.

GENUS: Rhomaleosaurus Seeley, 1874 (Seeley1874b)

TYPE SPECIES: Rhomaleosaurus cramptoni Seeley, 1874.

Rhomaleosaurus victor (Fraas, 1910)

TYPE MATERIAL: — Holotype: SMNS 12478.TYPE LOCALITY: Posidonien-Schiefer, Holzmaden, Germany.AGE: Toarcian.REFERRED MATERIAL: none.REMARKS: Fig. 7. The taxonomic history of this species iscomplex; this species was originally described as ‘Thau-matosaurus victor’ (Meyer 1841) by Fraas (1910). Thegenus Rhomaleosaurus is in need of revision (Cruick-shank 1994a; see below). Lydekker (1889b) attempted tomake Rhomaleosaurus a junior synonym of Thaumato-saurus, based on his opinion that Seeley’s type of thegenus, Rhomaleosaurus cramptoni (Seeley 1874b), doesnot differ from the type material of ‘Thaumatosaurus’.Tarlo (1960) rejected ‘Thaumatosaurus’ because the typematerial is not diagnostic (reviewed in Taylor 1992a).

Fig. 6. Plesiosaurus dolichodeirus palate, BMNH41101. Length of skull 20 cm.

Fig. 7. Rhomaleosaurus victor palate, SMNS 12478.Length of mandible 40 cm.


Tarlo (1960) also believed the complete skeleton named‘Thaumatosaurus’ victor by Fraas (1910) to be congener-ic with Rhomaleosaurus, and recommended dropping‘Thaumatosaurus’ altogether. I follow his suggestion.Lydekker (1889a) also referred an isolated jaw symphy-sis from India to Thaumatosaurus; the symphysis hascharacters diagnostic of the Rhomaleosauridae but is notdiagnostic at the genus level.

Rhomaleosaurus megacephalus Stuchbury, 1846

TYPE MATERIAL: — Holotype: lost. — Neotype: LEICTG221.1851 (Cruickshank 1994a).TYPE LOCALITY: Barrow upon Soar, Leicestershire, England.AGE: Earliest Hettangian.REMARKS: Fig. 8. Cruickshank (1994a) designates anddescribes the neotype, which is a complete skeletonsuperficially similar to the destroyed holotype describedand figured by Stuchbury (1846) under the name ‘Plesio-saurus’ megacephalus. Cruickshank (1994a) and Taylor(1992a) also discuss the taxonomic confusion surround-ing the name Rhomaleosaurus.

Rhomaleosaurus zetlandicus Phillips, 1854 (inAnon. 1854)

TYPE MATERIAL: — Holotype: YORYM G503TYPE LOCALITY: Alum Shale, Whitby, Yorkshire, England.

AGE: Toarcian.REMARKS: Taylor (1992a) discusses the taxonomy of thisspecimen and of Rhomaleosaurus in general. Taylor(1992b) describes the cranial anatomy of this taxon.

GENUS: Simolestes Andrews, 1909

TYPE SPECIES: Simolestes vorax Andrews 1909.TYPE MATERIAL: — Holotype: BMNH R.3319.TYPE LOCALITY: Oxford Clay, Peterborough, England.AGE: Callovian.REFERRED MATERIAL: none.REMARKS: Andrews (1913) and Tarlo (1960) describe thistaxon thoroughly.

GENUS: Leptocleidus Andrews, 1922

TYPE SPECIES: Leptocleidus capensis (Andrews, 1911a).TYPE MATERIAL: — Holotype: BMNH R.4828.TYPE LOCALITY: Berwick, Sussex, England.AGE: Barremian.REFERRED MATERIAL: SAM-K5822 (South African Museum).REMARKS: Cruickshank (1997) reviews the type materialof this genus and refers the South African specimen tothe genus. The type material was originally described byAndrews (1911a) under the genus name ‘Plesiosaurus’.

GENUS: Macroplata Swinton, 1930

TYPE SPECIES: Macroplata longirostris (Blake, 1876).TYPE MATERIAL: — Holotype: MCZ 1033.TYPE LOCALITY: Alum Shale, Whitby, Yorkshire, England.AGE: Toarcian.REFERRED MATERIAL: MAN UM 8004.REMARKS: Fig. 9. Macroplata longirostris was named anddescribed from a complete skeleton by Blake (1876) as‘Plesiosaurus’ longirostris. Swinton (1930) erected Mac-roplata for the specimen when he realized that it was notreferable to Plesiosaurus. However, as discussed byWhite (1940), Blake and later workers were aware thatthe specimen was a composite. Blake (1876) argued thatthe holotype be restricted to the skull only. White (1940)felt that the associated vertebral column might also beincluded in the holotype. The skull was prepared poorlyin Victorian times, and the serious ‘pyrite disease’ notedby White (1940) has continued to degrade the alreadybattered skull. However, several diagnostic characters arestill visible, such as the very long snout and the plesio-morphic, rhomaleosaur-like pattern of the posterior ba-sicranium. Both of these characters are shared by a newskull with associated complete skeleton in the Manches-ter Museum (MAN UM 8004), which was found at thesame locality and in the same formation as the holotype.The Manchester specimen also possesses a groove infront of the external naris, and a perforation in the dorsalsurface of the basisphenoid through which the clivus isvisible. Both of these characters are also present in theMacroplata holotype, and I therefore refer MAN UM8004 to this taxon.

Fig. 8. Rhomaleosaurus megacephalus palate, LEICTG221.1851. Length of mandible 42 cm.


GENUS: unnamed (‘Macroplata tenuiceps’).

TYPE SPECIES: n/a.TYPE MATERIAL: — Holotype: BMNH R.5488.TYPE LOCALITY: Harbury, Warwickshire, England.AGE: unknown.REMARKS: This specimen is a complete skeleton in thecollection of the Natural History Museum, London. Thespecimen is identified as ‘Macroplata tenuiceps’ on thelabels accompanying the material. The skeleton is cer-tainly not referable to this genus based on charactersnoted by Cruickshank (1994a), Swinton (1930), andWhite (1940). The specimen is certainly a rhomaleosau-rid, although the skull material is not diagnostic at thespecies level. The taxonomic status of this specimenawaits revision of the Rhomaleosauridae.

GENUS: Hauffiosaurus gen. n.

TYPE SPECIES: Hauffiosaurus zanoni sp. n.HOLOTYPE : Hauff Museum, uncatalogued; see above.TYPE LOCALITY: Posidonien-Schiefer, Holzmaden, Germany.AGE: Toarcian.REFERRED MATERIAL: none.REMARKS: Figs. 2 and 3. This specimen is a complete

skeleton of an unnamed taxon in the collections of theHauff Museum. The taxon is named here, and a prelimi-nary description is given above with figures of the skulland skeleton.

GENUS: Peloneustes Lydekker, 1889 (Lydekker1889b)

TYPE SPECIES: Peloneustes philarchus (Seeley, 1869).TYPE MATERIAL: — Holotype: CAMSM J.46913TYPE LOCALITY: Oxford Clay, Peterborough, England.AGE: Callovian.REFERRED MATERIAL: BMNH R.8574, R.3803, R.3897,R.3318.REMARKS: Figs. 10, 11 and 12. Lydekker names anddescribes this taxon (1889b), and comments on itsrelationships to Thaumatosaurus. Tarlo (1960) discuss-es this taxon, and Andrews (1913) describes it in detail.Linder (1913) describes Oxford Clay material of thistaxon at the SMNS, and compares it to Pliosaurus. Thistaxon is extremely well-represented by material in theLeeds collection in the Natural History Museum

Fig. 9. Macroplata longirostris palate, MAN UM8004.

Fig. 10. Peloneustes philarchus skull roof, BMNH R.8574. Length of skull 69.5 cm.


(BMNH), including several complete skeletons withwell-preserved skulls.

GENUS: Liopleurodon Sauvage, 1873

TYPE SPECIES: Liopleurodon ferox Sauvage, 1873.TYPE MATERIAL: — Holotype: BMNH R.3536.TYPE LOCALITY: Oxford Clay, Peterborough, England.AGE: Callovian.REFERRED MATERIAL: BMNH R.2680, GPIT 1754/2.REMARKS: Tarlo (1960) offered the latest review of UpperJurassic pliosaurs, and reviews the complex taxonomichistory of the genus name. Andrews (1913) describes thistaxon in detail under the name ‘Pliosaurus’ ferox. Thegenus Stretosaurus was a made a junior synonym of thistaxon by Halstead (1989); this poorly-defined taxon isbased on enormous pliosaurid postcranial elements fromthe Kimmeridge Clay. Further comparison of this materi-al with that of Pliosaurus is probably necessary.

GENUS: Pliosaurus Owen, 1841

TYPE SPECIES: Pliosaurus brachydeirus Owen, 1841.

TYPE MATERIAL: — Holotype: OXFUM J.9245 A,B.TYPE LOCALITY: Oxford Clay, Peterborough, England.AGE: Callovian.REFERRED MATERIAL: BMNH R.3891, BRSMG Cc332,‘Westbury Pliosaur 2’ (BRSMG uncatalogued.).REMARKS: Taylor and Cruickshank (1993) discuss thetaxonomic history of this genus. Tarlo (1960) also reviewsthis taxon. Referred specimens listed above are Kim-meridgean, from the Kimmeridge Clay in Wiltshire, UK.

GENUS: Brachauchenius Williston, 1903

TYPE SPECIES: Brachauchenius lucasi Williston, 1903.TYPE MATERIAL: — Holotype: USNM 4989.TYPE LOCALITY: Greenhorn Limestone, Ottawa County,Kansas, USA.AGE: Turonian.REFERRED MATERIAL: USNM 2361, FHSM VP321.REMARKS: Fig. 13. This taxon was described in detail byWilliston (1907). Carpenter (1996) referred the FortHayes skull to the genus.

GENUS: Microcleidus Owen, 1865

TYPE SPECIES: Microcleidus homalospondylus Owen, 1865.TYPE MATERIAL: — Holotype: YORYM G.502.TYPE LOCALITY: Alum Shale, Whitby, England.AGE: Toarcian.REFERRED MATERIAL: MM L. 7077.REMARKS: This genus is in need of redescription, havinglast been treated by Watson (1911).

GENUS: Brancasaurus Wegner, 1914

TYPE SPECIES: Brancasaurus brancai Wegner 1914.TYPE MATERIAL: — Holotype: Münster; Wegner does notgive the specimen number.TYPE LOCALITY: Münster, Westphalia, Germany.AGE: Valangian.REFERRED MATERIAL: none.REMARKS: Wegner’s (1914) thorough description is theonly publication on this taxon.

GENUS: Callawayasaurus Carpenter, 1999

TYPE SPECIES: Callawayasaurus columbienesis (Welles,1962).TYPE MATERIAL: — Holotype: UCMP 38349.TYPE LOCALITY: Columbia, South America.AGE: Aptian.REFERRED MATERIAL: UCMP 125328, partial skull. Samelocality.REMARKS: Fig. 14. This genus was erected by Carpenter(1999) for the holotype of ‘Alzadasaurus’ columbienesis(Welles 1962), an essentially complete elasmosaur skele-ton from the Aptian of Columbia. The skull shows anumber of primitive features. For holotype and otherinformation on Alzadasaurus proper see Welles (1962).

Fig. 11. Peloneustes philarchus palate, SMNS 10113.Length of skull 63 cm.


GENUS: Libonectes Carpenter, 1996

TYPE SPECIES: Libonectes morgani (Welles, 1949).TYPE MATERIAL: — Holotype: SMUSMP 69120.TYPE LOCALITY: Britton Formation, near Cedar Hill, Tex-as, USA.AGE: Coniacian.REFERRED MATERIAL: noneREMARKS: Fig. 15. Carpenter (1996) describes the well-preserved skull of this taxon, and erected the new genusname for a specimen that had been referred to Elasmo-saurus by Welles (1949).

GENUS: Styxosaurus Welles, 1943

TYPE SPECIES: Styxosaurus snowii (Williston, 1890).TYPE MATERIAL: — Holotype: KUVP 1301.TYPE LOCALITY: Niobrara Formation, Hell Creek, LoganCounty, Kansas, USA.AGE: Santonian.REFERRED MATERIAL: AMNH 5835.REMARKS: Reviewed in Welles (1943, 1952, 1962), andmore recently in Storrs (1999).

GENUS: Cryptoclidus Phillips, 1871

TYPE SPECIES: Cryptoclidus eurymerus Phillips 1871.TYPE MATERIAL: — Holotype: lost. — Neotype: BMNHR.2860 (Brown 1981).TYPE LOCALITY: Oxford Clay, Peterborough, England.AGE: Callovian.REFERRED MATERIAL: PETMG R.283, BMNH R.2417, GPIT1754/1.REMARKS: Andrews (1910) describes this taxon thorough-

Fig. 12. Peloneustes philarchusmandible, lingual view (top), BMNHR. 8574, length of illustrated por-tion 28 cm; lateral view, (bottom),BMNH R. 2439, Length of illustrat-ed portion 18 cm.

Fig. 13. Brachauchenius lucasi palate, USNM 4989.Length of mandible 112 cm.


ly. Brown (1981) redescribes this taxon and refers othermaterial to it. Brown and Cruickshank (1994) describethe skull in some detail from referred material.

GENUS: Muraenosaurus Seeley, 1874 (Seeley1874a)

TYPE SPECIES: Muraenosaurus leedsii Seeley, 1874 (See-ley 1874a).TYPE MATERIAL: — Holotype: BMNH R.2421.TYPE LOCALITY: Oxford Clay, Peterborough, England.AGE: Callovian.REFERRED MATERIAL: BMNH R.2678, R.2864, R.2863,R.2861, R.3704, LEICT G.18.1996.REMARKS: Andrews (1910) describes this taxon thorough-ly. Brown (1981) redescribes the skull and refers othermaterial to it.

GENUS: Tricleidus Andrews, 1909

TYPE SPECIES: Tricleidus seeleyi Andrews, 1909.TYPE MATERIAL: — Holotype: BMNH R.3539.TYPE LOCALITY: Oxford Clay, Peterborough, England.AGE: Callovian

Fig. 14. Callawayasauruscolumbienesis skull, lat-eral view, UCMP 38349.Length of skull 15.8 cm.

Fig. 15. Libonectes morg-ani mandible, lingual view,SMUSMP 69120. Lengthof fragment 28 cm.

REFERRED MATERIAL: none.REMARKS: Fig. 16. Described in Andrews (1910). Brown(1981) redescribes this taxon. Known from one fairlycomplete skeleton.

GENUS: Kimmerosaurus Brown, 1981

TYPE SPECIES: Kimmerosaurus langhami Brown, 1981.TYPE MATERIAL: — Holotype: BMNH R.8431.TYPE LOCALITY: Kimmeridge Clay, Dorset, England.AGE: Kimmeridgian.REFERRED MATERIAL: BMNH R.1798, R.10042.REMARKS: A poorly known but important taxon. Additionalmaterial described by Brown et al. (1986). The genusColymbosaurus, also from the Kimmerage Clay, may berelated to this taxon; however, no cranial material ofColymbosaurus is yet known (Brown 1984), and the taxonis in need of revision. The humerus of Colymbosaurus isvery similar to that of Polycotylus (Brown, 1981).

GENUS: Morturneria Chatterjee & Small, 1989

TYPE SPECIES: Morturneria seymourensis Chatterjee &Small, 1989


TYPE MATERIAL: — Holotype: TT VP9219.TYPE LOCALITY: Lopez de Bertodana Formation, SeymourIsland, Antarctica.AGE: Maastrichtian.REFERRED MATERIAL: none.REMARKS: This taxon is the best-known of a poorly-known groupof aberrant Cretaceous cryptoclidids. This group also includes thetaxon Aristonectes parvidens Cabrera 1941, from South Ameri-ca; like Morturneria this taxon is Maastrichtian in age.

GENUS: currently unnamed

TYPE SPECIES: n/a.TYPE MATERIAL: — Holotype: MOR 751.TYPE LOCALITY: Thermopolis Shale, Montana, USA.AGE: Upper Albian.REFERRED MATERIAL: none.REMARKS: This specimen is an unnamed, primitive poly-cotylid described in a thesis by Druckenmiller (1998).Druckenmiller has a publication naming this taxon inpress (Druckenmiller pers. com.).

GENUS: Polycotylus Cope, 1869

TYPE SPECIES: Polycotylus latipinnis Cope, 1869.TYPE MATERIAL: — Holotype: USNM 27678.TYPE LOCALITY: Niobrara Formation, Fort Wallace, Kan-sas, USA.AGE: Cenomanian.REFERRED MATERIAL: AMNH 2321, YPM 1125.REMARKS: Carpenter (1996) reviewed all Cretaceous plio-sauromorphs from North America. Polycotylus is thelargest of known polycotylids, and its skull is knownfrom very fragmentary material.

GENUS: Dolichorhynchops Williston, 1903

TYPE SPECIES: Dolichorhynchops osborni Williston 1903.TYPE MATERIAL: — Holotype: KUVP 1300.TYPE LOCALITY: Niobrara Formation, Logan County, Kan-sas, USA.AGE: Cenomanian.REFERRED MATERIAL: MCZ 1064, FHSM VP404REMARKS: Figs. 17, 18 and 19. Carpenter (1996) reviewedall Cretaceous pliosauromorphs from North America,including Dolichorhynchops.

GENUS: Trinacromerum Cragin, 1888

TYPE SPECIES: Trinacromerum bentonianum Cragin,1888.TYPE MATERIAL: — Holotype: USNM 10945.TYPE LOCALITY: Fencepost Limestone, Osborne County,Kansas, USA.AGE: Turonian.REFERRED MATERIAL: USNM 10946, MCZ 1064, FHSMVP404, KUVP 5070, SM 3025.REMARKS: Carpenter (1996) reviewed all Cretaceous plio-sauromorphs from North America, including Trinac-romerum.

Fig. 16. Tricleidus seeleyi palate, BMNH R. 3539.Length of illustrated portion 14 cm.

Fig. 17. Dolichorhynchops osborni palate, FHSMVP404. Length of illustrated portion 24 cm.


GENUS: Attenborosaurus Bakker, 1993

TYPE SPECIES: Attenborosaurus conybeari (Sollas, 1881).TYPE MATERIAL: — Holotype: lost; BMNH R.1339 (cast).TYPE LOCALITY: Charmouth, Dorset, England.AGE: Sinemurian (?).REFERRED MATERIAL: BMNH 40140, BMNH R.1360, BMNH39514.REMARKS: Described by Owen (1865) as ‘Plesiosaurusrostratus’, material referable to this taxon was renamedby Bakker (1993) to replace ‘Plesiosaurus’ conybeari(Sollas 1881), after Persson (1963) remarked that the

specimen was clearly not a member of the genus Plesio-saurus. Persson also noted that the skull was very similarto that of Rhomaleosaurus, but the postcranium wasplesiosauromorph; see O’Keefe (2002) for interpretation.

GENUS: Kronosaurus Longman, 1924

TYPE SPECIES: Kronosaurus queenslandicus Longman, 1924.TYPE MATERIAL: — Holotype: Queensland Museum;Longman (1924, 1930) does not list specimen number.TYPE LOCALITY: Army Downs, north of Richmond, Queens-land, Australia.REFERRED MATERIAL: MCZ 1284, 1285.REMARKS: Kronosaurus was originally described on thebasis of a fragment of mandibular symphysis and propo-dial fragments. The more complete Harvard material wascollected in 1931–1932 and described by White (1935).The Harvard skull has been on loan to C. McHenry forsome time, who is working on a redescription of thistaxon based on new material (C. McHenry pers. com.).An additional complete skeleton was assigned to thisgenus by Hampe (1992). Hampe also furnishes 22 char-acters and a cladogram of seven ‘pliosaur’ species.

Characters and coding

The 34 taxa listed above were scored for 166morphological characters. Of these characters,107 concerned the skull and 59 were postcrani-al. About half of the characters appear in theliterature in some form. Appendix 1 gives anumber and name for each character, the refer-ence (if any) for that character, a description ofstates, numerical codings, and any relevant re-marks. The references cited in the table are themost informative and generally the most recent

Fig. 18. Dolichorhynchopsosborni skull roof in ob-lique lateral view, MCZ1064. Length of illustrat-ed portion 39 cm.

Fig. 19. Dolichorhynchops osborni mandible, FHSMVP404; lateral (top), dorsal (middle), lingual (bot-tom). Length of illustrated portion 19 cm.


source for a given character, and the listing isnot exhaustive. The figures where states of agiven character are illustrated are listed in theremarks section for each character. Charactersare scored with the primitive state as zero forconvenience, and polarity was determined bycomparison with the outgroup. Most charactersare unordered; those that are ordered are notedin the remarks section. Characters are only or-dered if a second state is logically dependent onthe presence of the first state, such as charactersconcerning successive neck lengths or thenumber of maxillary teeth. Running all charac-ters as unordered results in identical results asrunning some characters as ordered. The matrixhas a relatively high proportion of charactersthat are inapplicable to some taxa, due largely to

the profound reorganizations of the pectoralgirdle and palate between the outgroup and theingroup. Characters which code only for theoutgroup were included to help establish thetopology within the outgroup, which can effectcharacter reconstruction at the basal node of theingroup and hence the ingroup topology. Char-acters which code only for the ingroup willaffect only the topology of the ingroup. Thepresence of both types of characters will notgive rise to spurious effects as long as the basalingroup node is strongly supported by othercharacters, and it is in this case (bootstrap value86%, decay index 6; see Fig. 20).

The data matrix (Appendix 2) was analyzedusing PAUP 3.1.1 (Swofford & Begle 1993).The non-plesiosaur taxa Simosaurus, Cymato-

Fig. 20. Phylogenetic relationships of the Plesiosauria. Topology shown is the strict consensus of 12 MPTs,tree lengths 432. CI = 0.47, RCI = 0.34, RI = 0.72. Numbers just below and to the left of a given node arebootstrap support values; those to the right are decay indices. Indices in parantheses are the support for agiven node after morphometric characters have been removed and analysis rerun. Dots represent nodeswith less than 50% bootstrap support and a decay index of one. Named groups are diagnosed in the text.


saurus, and Pistosauridae were specified as theoutgroup, and the outgroup was constrained tobe paraphyletic with respect to the ingroup toreflect the topology of Rieppel (2000). Theheuristic search strategy was used, using tree-bisection-reconnection (TBR) branch swapping.The reference taxon was random; iterationsshowed that using any taxon as the referencetaxon yielded the same set of trees. Initial analy-sis was run with all characters included andweighted equally. A second analysis was per-formed with the ‘morphometric’ characters re-moved, based on the finding that the pliosauro-morph body type may have evolved convergent-ly (O’Keefe 2002).

Results

Parsimony analysis of the data matrix yieldedtwelve most- parsimonious trees (MPTs), eachwith a tree length of 432. The strict consensustree computed from the twelve MPTs is shownin Fig. 20. The MPTs had a Consistency Index(CI) of 0.47, and a Rescaled Consistency Index(RCI) of 0.34 (excluding uninformative charac-ters). The Retention Index (RI) was 0.72. Iinvestigated the robustness of the strict consen-sus tree topology by bootstrapping the characterlist (1000 replicates), and by calculating decayindices (Bremer 1994) for each ingroup node.Bootstrap percentages and decay indices arestated beneath each node in Fig. 20. The tree iswell-supported with the exception of some cryp-tocleidoid relationships and the ingroup rela-tionships of the rhomaleosaurids.

The topology of clade Plesiosauria replicatesmany of the findings advanced by earlier work-ers. The basic dichotomy between the Plesiosau-roidea and the Pliosauroidea is a well-supportedfinding. Within the Pliosauroidea two largemonophyletic groups exist, the Rhomaleosauri-dae and the Pliosauridae, as suggested by Car-penter (1997). The base of the clade Pliosauroi-dea contains the plesiomorphic taxon Thalassio-dracon, as well as the plesiomorphic and transi-tional Eurycleidus. The basal position of Eury-cleidus was predicted by Cruickshank (1994b).The Polycotylidae is not a member of the Plio-sauroidea, establishing that the pliosauromorph

body type is a polyphyletic grade. To investigatethe stability of this result, parsimony analysiswas performed with the constraint of pliosau-roid/polycotylid monophyly in effect. This anal-ysis resulted in two MPTs with tree lengths of447, fifteen steps longer than the MPTs from theoriginal analysis. This large increase in treelength indicates that polyphyly of the traditionalPliosauroidea is a well-supported finding, andthat monophyly of the traditional Pliosauroideais unlikely.

Within the Plesiosauroidea, the monophyly ofthe Elasmosauridae is well-supported. TheCryptocleidoidea, however, is the one group inwhich the cladogram departs radically from thetraditional taxonomy. The placement of Mu-raenosaurus in this clade suggests that Muraeno-saurus is not an elasmosaur (contra Andrews1910). The elasmosaur-like long neck and smallhead evolved independently in Muraenosaurus.Also within the Cryptocleidoidea is a novel cladecomposed of Tricleidus, the Polycotylidae, andthe short-necked cryptocleidoids Kimmerosaurusand Morturneria. This clade documents the deri-vation of the pliosauromorph polycotylids from aTricleidus-like cryptocleidoid. Taxonomy ofclade Plesiosauria is revised below in the system-atic paleontology section of the discussion. Thetaxonomic revision is followed by a discussion ofcharacter transitions at various nodes.

To investigate the effect of morphometriccharacters on the tree topology, a PAUP analy-sis was run with the eight morphometric char-acters excluded (characters 1–7, 112). Thisanalysis resulted in 6 MPTs, each with a treelength of 387. The CI of these trees was 0.49,and the RCI was 0.36. The RI was 0.73. Thetopology of the strict consensus tree computedfrom this set of MPTs was almost identical tothe topology in the first analysis, differing onlyin the position of Microcleidus. In the firstanalysis Microcleidus formed a polytomy withtwo large clades, the elasmosaurs and crypto-cleidoids. The second, non-morphometric anal-ysis resolved this polytomy so that Microcleid-us became the outgroup to a clade in which theelasmosaurs and cryptocleidoids were sistertaxa. Microcleidus is a plesiomorphic and prob-lematic taxon, and it is treated as a stem taxonin this report.


The one area where the removal of themorphometric characters had a significant effectwas the tree length, and the RCI derived from it.The RCI increased from 0.34 to 0.36 in thesecond analysis. The MPTs derived from thesecond analysis were 47 steps shorter than thosederived from the first; this is an average ofalmost six steps for each of the eight morpho-metric characters. The average number of stepsper character for the rest of the data is about 2.5.The length of the neck and skull, and othercharacters of body proportion, are thereforemore labile than the remaining characters. Theobservation that the number of steps per mor-phometric character is about three times theaverage for the other characters can be ex-plained by the fact that the pliosauromorph bodytype evolved independently three times. Decayindices calculated on this tree showed minorimprovement for several nodes, and the reviseddecay indices appear in Fig. 20 in parenthesesnext to the indices from the primary analysis.

Discussion

The first section of this discussion is a revisionof the higher taxonomy of the Plesiosauria,based on the cladogram topology in Fig. 20. Thetaxonomic revision is followed by a short dis-cussion of characters important in the diagnosisof various clades and a short review of morpho-logical evolution in the Plesiosauria.

Systematic paleontology

The following is a revised taxonomy of thePlesiosauria. All diagnostic characters are de-scribed in Appendix 1, and scoring can be foundin the character matrix in Appendix 2. Allsynapomorphies listed in the diagnoses are unam-biguous. Character reconstructions that differ be-tween ACCTRAN and DELTRAN optimizationsare not listed. Only genera included in the presentanalysis are listed; note that the taxonomic sam-pling in this analysis is not exhaustive at thegenus level, especially within the Elasmosauridaeand Rhomaleosauridae. The definitions givenhere are node-based (see Sereno 1998, and refer-

ences therein for discussion). Taxa defined on thebasis of more than two taxa refer to clades whosebasal node is well-supported but whose internalrelationships are obscured by polytomy.

Sauropterygia Owen, 1860

DIAGNOSIS: diagnosed in Rieppel 1998.DEFINITION: A monophyletic taxon including thePlacodontia and the Eosauropterygia.

Pistosauria Rieppel, 1998

DIAGNOSIS: diagnosed in Rieppel 1998.DEFINITION: A monophyletic taxon including Cy-matosaurus, Pistosaurus, and the Plesiosauria.

Plesiosauria de Blainville, 1835

REVISED DIAGNOSIS: Maxilla/squamosal contactpresent; quadrate embayed anteriorly; parasphe-noid is exposed anterior to posterior interptery-goid vacuities on palate surface; cervical zygo-pophyses narrower than centrum width; dorsalneural arches shorter than centrum height; zy-gosphene/zygantrum articulation absent; longi-tudinal pectoral bar present; lack of articulationbetween ilium and pubis; expanded distal propo-dials with dorsal trochanter/tuberosity; ulna dis-tinctly lunate; shifted fifth metapodial present;hyperphalangy present.REVISED DEFINITION: A taxon including the Plesi-osauroidea, the Pliosauroidea, their most recentcommon ancestor, and all descendants.

Plesiosauroidea Welles, 1943

REVISED DEFINITION: A monophyletic taxon in-cluding Plesiosaurus and the Euplesiosauria,their most recent common ancestor, and alldescendants.REVISED DIAGNOSIS: Prefrontal contacts margin ofexternal naris; nasal absent; cervical neural spinesnot angled backward; dorsal neural spines com-pressed and blade-like.

Euplesiosauria (new taxon)

DIAGNOSIS: Relative skull length short; anteriorborder of pineal foramen formed by frontal;long lateral and short medial posterior processesof squamosal; jugal confined to posterior orbit


margin; supraoccipital deep with sigmoid ven-tral sutures; ectopterygoid contacts postorbitalbar out of palate plane; distinct change in angleof cervical zygopophyses; anterior processes ofscapula meet in median symphysis; longitudinalpectoral bar present, formed by coracoid andscapula; humerus not angled.DEFINITION: A taxon including the Elasmosauri-dae, the Cryptocleidoidea, and Microcleidus,their most recent common ancestor, and alldescendants.

FAMILY: Elasmosauridae Cope, 1870

REVISED DIAGNOSIS: Anterior quadrate embay-ment absent (reversal); premaxilla excludedfrom border of internal naris; vomer extendsposterior to internal nares; number of cervicalrib heads reduced to one; coracoids long withdeep median embayment; ventro-medial marginof pubis concave; ulna not lunate (reversal);epipodials wider than long.REVISED DEFINITION: A taxon including Branca-saurus, Styxosaurus, their most recent commonancestor, and all descendants.

Cryptocleidoidea Williston, 1925

REVISED DIAGNOSIS: Fin aspect ratio low; anteriorinterpterygoid vacuity wide with rounded ends;anterior parasphenoid short and blunt; coronoidexposed on lateral mandible surface; grooveformed by prearticular/socket in angular; atlascentrum exposed on lateral surface betweenintercentrum and neural arch; anterior neuralflange on cervical neural spines.REVISED DEFINITION: A taxon including the Cryp-toclididae, the Tricleidia, their most recent com-mon ancestor, and all descendants.

FAMILY: Cryptocleididae Williston, 1925

REVISED DIAGNOSIS: Humerus longer than femur,occipital condyle short with no groove, cervicalrib heads elongate.REVISED DEFINITION: A taxon including Muraeno-saurus, Cryptoclidus, their most recent commonancestor, and all descendants.

Tricleidia (new taxon)

DIAGNOSIS: Pterygoid medial process for articu-

lation with parasphenoid present; parasphenoidcontacts basioccipital on midline; basioccipitaltubers reduced and confluent with basisphenoidarticulation; cervical neural spines not com-pressed (reversal); clavicles meet in medialsymphysis behind notch.DEFINITION: A taxon including the Polycotylidae,the Cimoliasauridae, Tricleidus, their most re-cent common ancestor, and all descendants.

FAMILY: Cimoliasauridae Delair, 1959

REVISED DIAGNOSIS: Rostrum long, unconstricted,and hoop-like; paraoccipital process articulateswith squamosal only; teeth very small and nee-dle-like; number of premaxillary teeth seven orgreater; number of maxillary teeth much greaterthan thirty.REVISED DEFINITION: A taxon including Morturn-eria, Kimmerosaurus, their most recent commonancestor, and all descendants.

FAMILY: Polycotylidae Williston, 1908

REVISED DIAGNOSIS: Neck length short; ischiumlonger than pubis; maxillary/squamosal suturepresent and formed by posterior expansion ofmaxilla; pterygoids with distinct medial proc-esses which meet behind posterior interptery-goid vacuities; pterygoids dished lateral to pos-terior interpterygoid vacuities; mandibular sym-physis scoop-like or long; splenial included inmandibular symphysis; number of cervical ver-tebrae reduced; longitudinal pectoral bar presentand formed by clavicle and coracoid; posteriorperforations in coracoid; supernumerary ossifi-cations in propodial and epipodial rows; inter-locking phalanges anterior to fifth digit.REVISED DEFINITION: A taxon including Polycoty-lus, Dolichorhynchops, their most recent com-mon ancestor, and all descendants.

Pliosauroidea Welles, 1943

REVISED DIAGNOSIS: Snout constricted at premax-illa/maxilla suture; occipital condyle short withno groove; posterior bulb formed by squamosalspresent; pterygoids meet anterior to posteriorinterpterygoid vacuity; premaxilla excludedfrom internal naris margin; mandibular symphy-sis scoop-like or long; splenial included in man-


dibular symphysis; ventral keel present on cervi-cal vertebrae; posterior articulation for succeed-ing neural spine in cervical neural spines absent.REVISED DEFINITION: A taxon including Thalassi-odracon, an unnamed clade comprised of Eury-cleidus, Attenborosaurus, the Rhomaleosauri-dae, and the Pliosauridae, their most recent com-mon ancestor, and all descendants.

FAMILY: Pliosauridae Seeley, 1874 (Seeley, 1874)

REVISED DIAGNOSIS: Preorbital skull length longerthan postorbital skull length; rostrum elongate;no contact between premaxilla and externalnaris; distinct postero-lateral process of frontalabsent (reversal); anterior interpterygoid vacuityabsent (reversal); vomer reaches past internalnares and meets pterygoid in wide interdigitat-ing suture; mandibular symphysis long; numberof maxillary teeth between twenty and thirty;humerus not angled.REVISED DEFINITION: A taxon including Macro-plata, Brachauchenius, their most recent com-mon ancestor, and all descendants.

FAMILY: Rhomaleosauridae (Kuhn, 1961)

REVISED DIAGNOSIS: Grooves in front of externalnares present; paraoccipital process robust;squared lappet of pterygoid underlying ptery-goid quadrate ramus present; lateral palatal fen-estration present; bowed maxilla present; pre-maxillary/dentary fangs present; cervical centralengths less than heights; cervical zygopophysesas wide as centra (reversal).REVISED DEFINITION: A taxon including Rhomale-osaurus victor, Leptocleidus, their most recentcommon ancestor, and all descendants.

Comments on the classification

The above classification is based on the moreconservative first parsimony analysis, in whichall characters were included. The morphometriccharacters have high levels of homoplasy; suchhigh levels of convergence can arise, however,in rapidly-evolving characters, and can holdphylogenetic information, especially withinsmaller subclades (Chippindale & Wiens 1994).It is therefore conservative to base taxonomic

conclusions on the MPTs from all data. Nodesthat were not replicated in the non-morphomet-ric tree were not used in the classification.Taxonomic conclusions are also not based onnodes which have weak decay indices and boot-strap support. A good example is the Rhomaleo-sauridae. The genus Rhomaleosaurus is para-phyletic according to the cladogram althoughthe decay index and bootstrap values are low(decay index one, bootstrap support < 50%) forall rhomaleosaurid ingroup relationships. A for-mal revision of Rhomaleosaurus is best left untila more detailed cladistic analysis of the Rhoma-leosauridae is made.

The revised classification splits the Plesiosau-ria into four major subclades, two within thePlesiosauroidea and two within the Pliosauroidea.Within the clade Plesiosauroidea, the Elasmosau-ridae remains as traditionally defined, with Bran-casaurus as the most basal elasmosaur. See Car-penter (1999) for a more complete list of elasmo-saur taxa and a revised taxonomy of this clade.The Cryptocleidoidea is revised here to includethe Polycotylidae and Muraenosaurus; further-more, a new clade is recognized (the Tricleidia)comprising the Cimoliasauridae, the polycotylids,and Tricleidus. Tricleidus is a generalized form,falling out in a trichotomy with the other mem-bers of the Tricleidia. Tricleidus possesses sever-al synapomorphies linking it with the short-necked plesiosauroids, including the presence ofposterior medial processes of the pterygoids, re-duced basioccipital tubers, a median contact be-tween the basioccipital and parasphenoid, and thepossession of a third distinct articulation on thepropodials for a supernumery ossification in theepipodial row. All short-necked plesiosauroidsshare these traits.

A last, problematic taxon within the Plesio-sauroidea is Microcleidus. This taxon possessesseveral plesiomorphic characters such as reten-tion of a lunate ulna and retention of an angledhumerus; however, the skull is elasmosaur-likein the absence of an anterior interpterygoidvacuity and in the location of the jaw articula-tion (below the tooth row). The coracoids areknown from fragmentary material, but appearnot to have the posterior extensions and embay-ment synapomorphic of true elasmosaurs. Theneck is long and the cervical rib heads elongate,


although these characters are homoplastic. Be-cause of this homoplasy the topology given bythe morphometric-omitted cladogram is proba-bly more accurate in this case, with Microcleid-us forming the sister taxon to a clade consistingof the Elasmosauridae and Cryptocleidoidea.The outgroup to this clade is the very plesiomor-phic Plesiosaurus. A thorough redescription ofthis taxon based on the type material as well asanother complete skeleton at Manchester shouldshed more light on this genus.

The clade Pliosauroidea includes two long-recognized clades of pliosaurs, the Rhomaleo-sauridae and the Pliosauridae, as well as theplesiomorphic stem taxa Thalassiodracon, Eury-cleidus, and Attenborosaurus. Of the two majorpliosauroid clades, the Pliosauridae possessesmore derived characters. The rhomaleosauridsare conservative, similar to Thalassiodracon(and hence plesiomorphic) in the palate, skullroof, and postcranium. This conservatism ispartially responsible for the lack of support forintrafamilial rhomaleosaurid relationships. Chang-es in relative neck and skull length and a greatincrease in body size are the only known trendsin this clade.

In contrast to the Rhomaleosauridae, thePliosauridae is morphologically derived, andgood intermediates exist that document the deri-vation of the pliosaurid conditions of the skullroof, palate and braincase. The monophyly ofthe Pliosauridae is a correspondingly well-sup-ported finding. The plesiomorphic taxa Eury-cleidus and Attenborosaurus form a polytomywith the Pliosauridae and Rhomaleosauridae.The taxonomic status of these genera are leftopen, and the Pliosauridae is limited to Macro-plata and more derived taxa.

Major patterns in plesiosaur cranialevolution

This overview describes the morphology of thefour major plesiosaur subclades in variable re-gions of the skull. These areas are the skull roof,the palate, and the braincase. Discussion of theanatomy characteristic of each subclade is in-tended as an aid to future classification.

The skull roof

An important feature of the skull roof is theretention of the nasals in Thalassiodracon andthe rest of the Pliosauroidea. Nasals werethought to be absent in all plesiosaurs by Storrs(1991); however, the loss of nasals diagnosesonly the Plesiosauroidea, not the Plesiosauria asa whole. The nasals in all pliosauroid taxa aresmall but present, and usually form the posteriormargin of the external nares. The pliosauroidcondition is very similar to that of Cymatosau-rus. In some very derived members of the Plio-sauridae, the nasal forms the anterior rather thanthe posterior margin of the external naris. Thenasals in all pliosaurs lack a midline suture,being separated on the midline by processes ofthe premaxillae.

The pattern of circumorbital bones is diag-nostic within the Plesiosauria. The lacrimal isabsent in all plesiosaurs due to its loss in morebasal sauropterygians (Rieppel 1997b). The pre-frontal and postfrontal do not exclude the frontalfrom the orbital margin in early plesiosaurs, andthis condition is retained in all plesiosauroids,including the polycotylids. However, the frontalis excluded from the orbital margin in all morederived rhomaleosaurids and pliosaurids. Thejugal is also diagnostic; in the most primitiveplesiosauroids and pliosauroids the jugal reach-es anteriorly to about the midpoint of the ventralorbital margin, which is plesiomorphic (Rieppel1997b). In more derived plesiosauroids the jugalis restricted to the posterior orbital margin. Thiscondition contrasts with that in more derivedpliosauroids, where the jugal reaches far anteriorto the orbit and forms its anterior border, meet-ing the prefrontal and excluding the maxillacompletely from the orbital margin. The pres-ence of a prominent anterior process of the jugaland its contact with the prefrontal probablyaccount for its misidentification as a lacrimal byearlier workers (Andrews 1913, Taylor &Cruickshank 1993).

The cryptocleidoids are extreme in their spe-cialization of the cheek region (Brown &Cruickshank 1994, Brown 1993). In Cryptoclid-us and Tricleidus the contact between maxillaand squamosal is lost, and the jugal forms a


narrow bar connecting these two elements be-neath the orbit. This area of the cheek is notknown in Muraenosaurus or the Cimoliasauri-dae. This condition is reversed in the polycoty-lids, where the maxilla again forms a suture withthe squamosal. The morphology of this suturediffers from the corresponding suture in truepliosaurs. In true pliosaurs the maxilla/squamos-al suture is small and not significant, and thejugal is large and has a prominent lateral suturewith the squamosal. In the polycotylids the jugalis small and restricted to the posterior orbitalmargin, and does not form a prominent suturewith the squamosal. The major suture in thisregion is that between the maxilla and squamos-al, which is formed by an expanded posteriorprocess of the maxilla. A possible explanationfor this pattern is secondary strengthening ofthis area of the skull made necessary by theevolution of a long snout in taxa with a highlyreduced cheek region, such as Tricleidus.

A feature that evolves repeatedly in long-snouted taxa is a contact between the dorsalprocesses of the premaxillae and the parietals. Amedian premaxilla/parietal suture evolves fourtimes, once each in the three derivations of thepliosauromorph body type and once in relativelylong-snouted elasmosaurs. This suture probablyserves to strengthen the interorbital region of theskull in response to greater forces produced at thetip of the long snout. A long snout is alsogenerally correlated with larger tooth size and amore robust skull in general; larger teeth proba-bly indicate larger average prey size and a con-comitant need to reinforce the skull. The robustmaxilla/squamosal suture in the polycotylids isalso interpretable as a means of strengthening theskull in response to increased snout length.

The palate

The primitive plesiosaur palate is derived com-pared to the condition in more basal sauroptery-gians. The plesiomorphic condition for the ple-siosaur palate is shown by Thalassiodracon andPlesiosaurus; both taxa possess anterior andposterior interpterygoid vacuities exposing theventral surface of the braincase. The pterygoids

do not meet behind the posterior interpterygoidvacuities in either taxon. In Plesiosaurus, thepterygoids also fail to meet between the posteri-or and anterior vacuities, exposing the cultri-form process of the parasphenoid (Storrs 1997).This open palate is retained (with some modifi-cation) in all members of the Cryptocleidoidea.In the Elasmosauridae and Microcleidus, how-ever, the anterior interpterygoid vacuity is ab-sent. The pterygoids also meet in a prominentmidline suture behind the posterior interptery-goid vacuity in all elasmosaurs, but not in Mi-crocleidus. Elasmosaurs are therefore character-ized by a secondarily closed palate, and thiscondition is foreshadowed to some extent inMicrocleidus.

The anterior interpterygoid vacuity is small inThalassiodracon, and is separated from the poste-rior vacuities by a long midline suture of thepterygoids. This pattern is retained withoutchange in the rhomaleosaurids. The rhomaleosau-rids are advanced over Thalassiodracon, howev-er, in possessing a contact of the pterygoidsbehind the posterior interpterygoid vacuity; thiscontact is partial in the plesiomorphic speciesRhomaleosaurus megacephalus and complete inall later rhomaleosaurids. The anterior palate ofrhomaleosaurs is like that of Eurycleidus, andunlike that of derived pliosaurids, in that thevomers do not extend far posterior to the internalnares. The Thalassiodracon material is not suf-ficiently well preserved to establish the presenceor absence of sub-orbital fenestrae (Storrs &Taylor 1997). This feature occurs in some rhoma-leosaurids and some pliosaurids. The presence orabsence of sub-orbital fenestrae can be difficult toestablish because the palatine is very thin and israrely preserved intact.

In contrast to that of rhomaleosaurids, thepalate in pliosaurids is highly derived comparedto the plesiomorphic condition in Thalassiodra-con. The anterior interpterygoid vacuity isclosed in the intermediate form Macroplata. Thevomers extend posterior to the internal nares andmeet the pterygoids in a wide, interdigitatingsuture in Macroplata, as well as in Hauffiosau-rus and all more derived pliosaurids. The quad-rate flange of the pterygoid is wide, sigmoid inshape, and possesses a ridged lateral margin in


Kronosaurus, Peloneustes, Liopleurodon, Plio-saurus, and Brachauchenius. The pliosauridsMacroplata and Hauffiosaurus are plesiomor-phic for this character; however, Attenborosau-rus is derived, possessing the ridged lateralmargin and sigmoid shape of the quadrate ptery-goid flange. Attenborosaurus is intermediate foranother synapomorphy of derived pliosaurids,namely the elaboration of lateral flanges of thepterygoid on either side of the posterior interpt-erygoid vacuities. These flanges are present inKronosaurus and all more derived pliosaurids,although they fuse over the posterior end of theinterpterygoid vacuity in Liopleurodon andmore derived forms. The elaboration of theseflanges gives the posterior palate a distinct two-tiered morphology in lateral view, with thelateral flanges, ventral braincase structures, andinterpterygoid vacuity on a more ventral leveland the quadrate pterygoid flanges reaching dor-sally and caudally back toward the quadrates ona more dorsal level. The polycotylids show notrace of this condition; the palate in this group isvery similar to the cryptocleidoid pattern, asobserved by Carpenter (1997).

The mandible

The plesiosaurian mandible has been a source ofconfusion for many years. The presence of thecoronoid and prearticular bones has been debat-ed; Andrews illustrates both bones as absent inMuraenosaurus (1910) and the prearticular asabsent in Peloneustes (1913). Cruickshank(1994b) states that absence of the coronoid istypical of plesiosauroids, and that the prearticu-lar is usually absent as well. Storrs and Taylor(1996) illustrate a prearticular but no coronoidin Thalassiodracon, while Taylor (1992b) illus-trates both bones as present in Rhomaleosaurus.I believe the prearticular is present in all taxawith adequately preserved material. The coro-noid is present in all taxa but Kimmerosaurus.The morphology of the lower jaw in plesiosau-roids is illustrated here by Libonectes (Fig. 15)and Dolichorhynchops (Fig. 19), and that ofpliosauroids by Peloneustes (Fig. 12). The lin-gual surface of the lower jaw is poorly ossifiedin plesiosaurs and the Meckelian canal is often

open for some of its length. The bones coveringthe Meckelian canal (splenial, coronoid, andprearticular) are very thin and often damaged orlost in fossils, which may account for the confu-sion concerning the two smaller bones.

The lower jaw symphysis was taken as animportant taxonomic character by Tarlo (1960)and later workers. The simple, unexpanded sym-physis present in most plesiosauroids is in factderived over the primitive condition exemplifiedby Thalassiodracon (Storrs & Taylor 1996) orthe outgroup taxon Cymatosaurus (Rieppel1997b). In these taxa the symphysis is rein-forced and scoop-like (Rieppel 1997b, character51), and the presence of a scoop-like symphysisin Rhomaleosaurus and related taxa is plesio-morphic. The snout and lower jaw symphysisbecomes very elongate in the most primitivemembers of the Pliosauridae and remains astereotyped feature of that family. The length ofthe symphysis does vary within this group,remaining very long in Peloneustes and revert-ing to scoop-like in Liopleurodon, Pliosaurus,and related taxa. A long lower jaw symphysis isalso present in all members of the Polycotylidae,where a long snout evolved convergently.

The braincase

The morphology of the braincase is known tovarying degrees in different plesiosaur subc-lades. In the elasmosaurids and rhomaleosauridsvery little is known, because a broad suture ofthe pterygoids between the posterior and anteri-or interpterygoid vacuities obscures most of theanterior braincase in ventral view (although seeCarpenter, 1997, for comments on the moredorsal elements of the elasmosaur braincase).More is known concerning the cryptocleidoidsand pliosaurids, in which the posterior interpt-erygoid vacuities are larger and open fartheranteriorly. In addition, the brain case is not astightly integrated into the skull roof in the latertaxon, so that the elements are more often pre-served in a visible manner.

The braincases of Plesiosaurus and Thalas-siodracon are similar, and are very primitivewhen observed in ventral view. The occipitalcondyle is hemispherical in Plesiosaurus and set


off from the body of the basioccipital by agroove, while in Thalassiodracon the condyle isless rounded with no groove (Storrs and Taylor1996, Storrs 1997). These condyle morpholo-gies are characteristic of later plesiosauroids andpliosauroids, respectively. The occipital condylemay have a notochordal pit; the pit is moreobvious in material from younger animals, andthere is intraspecific variation in its presence.The body of the basioccipital is a short, robustblock of bone, with paired articulations on itsdorsal surface for the exoccipitals (see Brown1981; Fig. 1). The basioccipital produces twoprominent basioccipital tubers projecting ante-ro-ventrally that articulate with the pterygoids.The exoccipitals are columnar bones rising dor-sally on either side of the foramen magnum, andgiving rise laterally to slender paraoccipitalprocesses that trend laterally to articulate withthe squamosals. The occiput is therefore open,and the suture between exoccipital and opisthot-ic is seldom visible (Storrs and Taylor 1996).The medial surface of each exocciptal is piercedby the jugular foramen and by one or twoforamina for the passage of the hypoglossalnerve (Storrs and Taylor 1996, Carpenter 1997).

In Plesiosaurus and Thalassiodracon, thebasioccipital tubers also articulate on their ante-rior margins with lateral processes of the paras-phenoid. These lateral parasphenoid processesare termed cristae ventrolaterales following Re-isz (1981: p. 24). The possession of the cristaeventrolaterales is a plesiomorphic condition foundin Petrolacosaurus (Reisz 1981) and Araeoscelis(Vaughn 1955). In these plesiomorphic taxa, thecristae ventrolaterales are two crests of bonesurrounding a deep basisphenoid fossa on themidline, with the posterior margin of the basi-sphenoid visible in the floor of this fossa. Thecondition in basal plesiosaurs is similar, exceptthe basisphenoid fossa has been filled with a discof basisphenoid confluent with the ventral planeof the cristae ventrolaterales. In Petrolacosaurusand Araeoscelis, the body of the parasphenoidruns forward into a long, narrow cultriform proc-ess. Plesiosaurus has a similar cultriform proc-ess. The condition in Thalassiodracon is un-known due to that taxon’s possession of a medi-an pterygoid suture between the posterior andanterior interpterygoid vacuities. Ventral to the

parasphenoid in the region of origin of the cultri-form process is the dorsum sellae and the bodyof the basisphenoid (the clivus) just posterior toit, a shelf of bone which ossifies just posterior tothe sella turcica (Romer 1956). In both Plesio-saurus and Thalassiodracon the basisphenoid iswell ossified, and the basal articulations arisinglaterally from it are prominent. Like Araeoscelis,Thalassiodracon possesses foramina in the ven-tral surface of the basisphenoid for the passageof the paired internal carotid arteries. The pres-ence or absence of these foramina was impossi-ble to establish in Plesiosaurus. These foraminaare not ossified in Eurycleidus, and the basisphe-noid facet of the basal articulation was impossi-ble to identify as a distinct feature (Cruickshank1994b). These observations probably arise fromthe fact that the Eurycleidus braincase material isfrom a juvenile, and so is not well-ossified.However, lack of ossification of the basisphe-noid is also characteristic of later pliosaurids, sothe condition in Eurycleidus may foreshadowthis to some degree. All plesiosaurs share a lackof ossification of the lateral walls of the brain-case. The area of origination of the pila antoticafrom the dorsal surface of the basisphenoid istherefore impossible to identify.

Two major changes to the plesiomorphicpattern of the plesiosaur braincase can be identi-fied in more derived groups. In the cryptoclei-doids the palate remains open and the skull roofis gracile, while the braincase is well-ossified.The cristae ventrolaterales disappear and theparasphenoid loses the characteristic triangularshape present in Araeoscelis and Plesiosaurus.The parasphenoid becomes a massive, block-like medial structure extending caudally almostto the basioccipital in more primitive cryptoclei-doids, and forming a novel median suture withthe basioccipital in more derived taxa (seeFig. 21). The cultriform process is also lost; theanterior margin of the parasphenoid becomesbroad and blunt and develops novel articulationswith the pterygoids on its antero-lateral edges.In contrast to the parasphenoid, the basisphe-noid in this group is conservative. Facets for thebasal articulation are well-defined, and the inter-nal carotid foramina pierce the body of thebasisphenoid ventro-laterally and run into thefloor of the sella turcica.


Fig. 21. Schematic transformation series of the basicranium and posterior palate, Plesiosauroidea. Ho-mologous bones are indicated in shades of gray. The plesiomorphic condition for this clade is demon-strated by Plesiosaurus. The palate is broadly open, and the pterygoids lack a median suture betweenboth the anterior and posterior interpterygoid vacuities, and beneath the basiocciptal. The parasphenoid isexposed medially along its entire length, the cultriform process is wide and prominent, and is confluentwith a ventral eminence or ridge running posterior to the exposed basisphenoid on the midline. Thebasisphenoid is visible in ventral view in two areas: anteriorly the processes comprising the basalarticulation are visible in the anterior of the posterior interpterygoid vacuities, while posteriorly an island ofbasisphenoid is exposed between parasphenoid and basioccipital. In elasmosaurs, here represented byLibonectes, this pattern is modified by the formation of a median pterygoid suture over the basioccipitaland basisphenoid. The anterior interpterygoid vacuity is also closed. In Tricleidus, however, the anteriorinterpterygoid vacuity stays open and the cultriform process losses its pointed anterior end, insteaddeveloping prominent later sutures with the pterygoids. The ventral eminence of the parasphenoid reach-es almost to the basiocciptal, and is broad along its entire length. Each pterygoid develops a novelprocess reaching medially to the ventral eminence of the parasphenoid. The basal articulation is well-developed, and the ectopterygoid reaches dorsally to the ventral surface of the postorbital bar. Thesituation in Dolichorhynchops is very similar, except that the medial processes of the pterygoids meet in asuture ventral to the basiocciptal. Additionally, the ventral eminence of the parasphenoid reaches far tothe posterior, overriding the basiocciptal and the median suture of the pterygoids.

In derived pliosaurids, the skull roof andpterygoids are massive and well-ossified, where-as the braincase is poorly ossified. In pliosauridssuch as Peloneustes, the anterior margin of theparasphenoid articulates tightly with the ptery-goids at the anterior margin of the posterior

interpterygoid vacuities. From this articulationthe parasphenoid runs caudally, expanding intothe plesiomorphic triangular shape. However,the parasphenoid ends after a short distance,articulating with the basisphenoid on the mid-line. The cristae ventrolaterales are again absent.


The basisphenoid is usually preserved as a ru-gose and unremarkable barrel of bone betweenthe parasphenoid and the basioccipital. In lifethe basisphenoid was completely encased incartilage, and the dorsum sellae and sella turcicausually failed to ossify. One extremely well-preserved skull of Peloneustes (BMNH 3803)does preserve a poorly ossified basisphenoid.Enough morphology is visible on this specimento establish that the basal articulation is presentin the plesiomorphic location, and the pterygoidfacet of the basal articulation is usually identifia-ble in skulls of Peloneustes. Foramina for theinternal carotids were not preserved in this spec-imen. In conclusion, the braincase in pliosauridsis a poorly ossified structure showing few mor-phological details in most specimens; well-pre-served specimens seem to demonstrate that thecartilaginous elements of the braincase retainedthe plesiomorphic pattern seen in Thalassiodra-con. Trends in basicranium evolution are illus-trated in two summary figures (Figs. 21 and 22).

Trends in postcranial evolution

The most remarkable aspect of plesiosaur post-cranial evolution is the convergent attainment ofbody morphotypes. The ‘pliosauromorph’ bodytype, characterized by a relatively large head,short neck, relatively long coracoids and ischia,and low aspect-ratio paddles, evolves in threeplesiosaur clades (Rhomaleosauridae, Pliosauri-dae, Polycotylidae; for analysis and discussionsee O’Keefe 2002). This striking convergence isresponsible for the polyphyly of the Pliosauroideaas traditionally defined, because characters ofbody overall body proportion were the basis oftraditional taxonomy (e.g. Persson 1963). Thisanalysis strongly rejects the traditional hypothesisthat all pliosauromorph taxa form a monophyleticgroup. In addition, the long neck thought to becharacteristic of elasmosaurs exclusively alsoevolved in the cryptoclidid Muraenosaurus (con-tra Andrews 1910, Persson 1963).

Several specific trends in the limb girdlesand limbs also deserve mention. Stratigraphical-ly early and plesiomorphic plesiosaurs, includ-ing Thalassiodracon and Plesiosaurus, retain adistinct bend or angle in the shaft of the humerus

Fig. 22. Schematic transformation series of the ba-sicranium and posterior palate, Pliosauroidea. Ho-mologous bones are indicated in shades of gray.The plesiomorphic condition for this clade (andprobably for plesiosaurs in general) is demonstrat-ed here by Thalassiodracon. The pattern in thistaxon is very similar to that described for Plesio-saurus in Fig. 21, except that the pterygoids meetin a median suture anterior to the posterior interpt-erygoid vacuities, and the parasphenoid is suturedto the pterygoids on the midline. The cultriformprocess is not visible in ventral view. The anteriorinterpterygoid vacuity is present but not illustratedhere; it is visible in Fig. 4. The pattern in Rhomale-osaurus is very similar to Thalassiodracon, theonly difference being a median suture of the ptery-goids over the basiocciptal and basisphenoid (par-tial in R. megacephalus, complete in most otherrhomaleosaurs). By contrast the palate is very de-rived in true pliosaurs, here represented by Pelone-ustes. The parasphenoid is not ossified around thebasisphenoid as in other plesiosaurs, although giv-en that the parasphenoid is dermal bone it isdoubtful that it persisted in cartilage. The basisphe-noid is very poorly ossified, and the basal articula-tion was cartilaginous. The pterygoids form ventralflanges lateral to the posterior interpterygoid vacui-ties that curve medially and meet beneath the basi-occiptal. The quadrate flanges of the pterygoidsare prominent, sigmoid processes which overridethe lateral flanges of the pterygoids.


(Storrs 1997). All ‘nothosaur’-grade sauroptery-gians also have this bend (Rieppel 1997b), whilethe shaft of the humerus is straight in all morederived plesiosaurs (Storrs 1997). Correlatedwith this transition is the loss of the ‘lunate ulna’in more derived plesiosaurs; plesiomorphic ple-siosaurs have epipodials that, while short, arevery similar to those in ‘nothosaur’-grade sau-ropterygians, and recognizable as radius, ulna,tibia, and fibula (Storrs 1997). In more derivedplesiosaurs these bones become unidentifiableon the basis of morphology, being simple ossi-fied disks integrated into the other ossificationsof the flipper (Storrs 1993, Caldwell 1997a,1997b). The functional significance of thesetransitions has yet to be investigated. A lastcharacter of note is the presence of a mediansymphysis of the scapulae. All plesiosauroidswere thought to have this symphysis (Persson1963); however, the placing of the Polycotylidaewithin the Plesiosauroidea demonstrates thatthis character is reversed in the polycotylids.This placement may also explain the similaritiesin the humeri of Polycotylus and Colymbosau-rus, although revision of the later taxon is neces-sary. A character of unknown signifigance is thescalloped margin of the vertebral centra in manycryptocleidoids; this may be a synapomorphy ofthis clade but further research is necessary. Ifpresent, however, the character would form an-other link between the Polycotylidae and theCimoliasauridae. The Cimoliasauridae certainlydeserve further research effort, both on knownmaterial and through field work.

Conclusions

1. The Plesiosauria is a monophyletic clade ofsauropterygians most closely related to thePistosauridae.

2. The Plesiosauria is composed of variousstem taxa and four major derived clades.These clades are the Rhomaleosauridae andPliosauridae within the Pliosauroidea, andthe Cryptocleidoidea and Elasmosauridaewithin the Plesiosauroidea.

4. The Rhomaleosauridae is a highly conserva-tive, plesiomorphic clade, most similar to thebasal pliosauroid Thalassiodracon.

3. The Polycotylidae is not a member of thePliosauroidea, and is instead a derived groupof cryptocleidoids.

4. Morphometric characters relating to bodyproportions are very homoplastic in the Ple-siosauria, and the pliosauromorph body typeevolved three times.

5. Nasals are present in all members of thePliosauroidea.

6. The plesiosaur braincase is very primitive,comparable to that of primitive diapsids suchas Araeoscelis.

Acknowledgements

This project was part of a doctoral dissertationsubmitted to the University of Chicago. Thedissertation was advised by J. Hopson and O.Rieppel, whose constant patience and assistanceof all kinds were critical to the project’s comple-tion. J. Hopson allowed me access to R. T.Zanon’s unpublished research, which was veryhelpful in getting the project started. C. Abraczin-skas taught me to draw what I see and made thisproject possible. A. Dudek, D. and S. O’Keefe,and M. Silverman provided help and support of aphysical, emotional, and/or metaphysical nature.

The following people assisted in visits tocollections at various institutions, and I thankthem all for their hospitality and help of allkinds: M. Benton, R. Vaughan, G. Dyke, T.Sharpe, J. Nudds, A. Cruickshank, J. Martin, P.Manning, M. Evans, A. Dawn, P. Powell, D.Norman, M. Dorling, S. Chapman, A. Milner, S.Donovan, M. Taylor, K. Padian, P. Holroyd, S.Parris, D. Parris, D. Miao, L. Martin, S. Chatter-jee, M. Brett-Surman, M. Turner, G. Gaffney, C.Holton, D. Schaff, R. Schoch, R. Hauff, M.Maisch, R. Wild, R. Zakrzewski, D. Lintz, L.Jacobs, J. Head, D. Winkler.

This manuscript benefitted from thoroughand very helpful reviews by O. Rieppel, J.Hopson, M. Sander, and G. Storrs. Their help isgratefully acknowledged. This research wassponsored in part by grants from the Samuel P.Welles Fund, the University of Chicago Wom-en’s Board, the University of Chicago HindsFund, and a Nierman Award. An Area 271Publication.


References

Andrews, C. W. 1895: On the structure of the skull ofPeloneustes philarchus. — Annals and Magazine ofNatural History, London 16(6): 242–256.

Andrews, C. W. 1896: On the structure of the plesiosauri-an skull. — Quarterly Journal of the GeologicalSociety, London 52: 246–253.

Andrews, C. W. 1909: On some new Plesiosauria fromthe Oxford Clay of Peterborough. — Annals andMagazine of Natural History, London 4(8): 418–429.

Andrews, C. W. 1910: A catalogue of the marine reptilesof the Oxford Clay, Part I. — British Museum(Natural History), London, England.

Andrews, C. W. 1911a: Description of a new plesiosaur(Plesiosaurus capensis, sp. nov.) from the UitenhageBeds of Cape Colony. — Annals of the South AfricanMuseum 1: 309–322.

Andrews, C. W. 1911b: On the structure of the roof of theskull and of the mandible of Peloneustes, with someremarks on the plesiosaurian mandible generally. —Geological Magazine of London 8: 160–164.

Andrews, C. W. 1913: A descriptive catalogue of themarine reptiles of the Oxford Clay, Part II. — BritishMuseum (Natural History), London, England.

Andrews, C. W. 1922: Description of a new plesiosaurfrom the Weald Clay of Berwick (Sussex). — Quar-terly Journal of the Geological Society of London 78:285–295.

Anonymous. 1854: Report of the council of the YorkshirePhilosophical Society 1853: 7–8.

Bakker, R. 1993: Plesiosaur extinction cycles — events thatmark the beginning, middle, and end of the Cretaceous.— In: Caldwell, W. G. E. & Kauffman, E. G. (eds.),Evolution of the Western Interior Basin: 641–664.Geological Survey of Canada, Special Paper 39.

Bardet, N. 1998: A preliminary cladistic analysis of thePlesiosauria. — Journal of Vertebrate Paleontology18(3) supp.: 26A.

Benton, M. J. & Spencer, P. S. 1995: Fossil reptiles ofGreat Britain. — Chapman and Hall, London.

Blake, J. F. 1876: Plesiosaurus longirostrus. — Tate, R.& Blake, J. F. (eds.), The Yorkshire Lias: 250–252.Van Voorst, London.

Brown, D. S. 1981: The English Upper Jurassic Plesio-sauroidea (Reptilia) and a review of the phylogenyand classification of the Plesiosauria. — Bulletin ofthe British Museum of Natural History (geol.) 35(4):253–347.

Brown, D. S. 1984: Discovery of a specimen of theplesiosaur Colymbosaurus trochanterius (Owen) onthe island of Portland. — Proc. Dorset Nat. Hist.Archaeol. Soc. 105: 170.

Brown, D. S. 1993: A taxonomic reappraisal of thefamilies Elasmosauridae and Cryptoclididae (Reptil-ia: Plesiosauridae). — Revue de Paleobiologie Spe-cial Volume (7): 9–16.

Brown, D. S. & Cruickshank, A. R. I. 1994: The skull of

the Callovian plesiosaur Cryptoclidus eurymerus andthe sauropterygian cheek. — Palaeontology 37 (4):941–953.

Brown, D. S., Milner, A. C. & Taylor, M. A. 1986: Newmaterial of the plesiosaur Kimmerosaurus langhamiBrown from the Kimmeridge Clay of Dorset. —Bulletin of the British Museum of Natural History(geol.) 40(5): 225–234.

Cabrera, A. 1941: Un plesiosaurio neuvo del Cretáceo delChubut. — Revisita del Museo de la Plata (NeuvoSerio) 2(8): 113–130.

Caldwell, M. W. 1997a: Limb osteology and ossificationpatterns in Cryptoclidus (Reptilia: Plesiosauroidea)with a review of Sauropterygian limbs. — Journal ofVertebrate Paleontology 17(2): 295–307.

Caldwell, M. W. 1997b: Modified perichondral ossifica-tion and the evolution of paddle-like limbs in ichthy-osaurs and plesiosaurs. — Journal of VertebratePaleontology 17(3): 534–547.

Carpenter, K. 1996: A review of short-necked plesiosaursfrom the Cretaceous of the western interior, NorthAmerica. — Neues Jahrbuch Geol. Palaönt. Abh.201(2): 259–287.

Carpenter, K. 1997: Comparative cranial anatomy of twoNorth American Cretaceous plesiosaurs. — In: Call-away, J. M. & Nicholls, E. L. (eds.), Ancient marinereptiles: 191–216. Academic Press, San Diego, Cali-fornia.

Carpenter, K. 1999: Revision of North American elasmo-saurs from the Cretaceous of the western interior. —Paludicola 2(2): 148–173.

Carroll, R. T. 1988: Vertebrate paleontology and evolu-tion. — W. H. Freeman and Company, New York.

Carroll, R. T. & Gaskill, P. 1985: The nothosaur Pachyp-leurosaurus and the origin of plesiosaurs. — Philo-sophical Transactions of the Royal Society of LondonB 309: 343–393.

Chatterjee, S. & Small, B. J. 1989: New plesiosaurs from theUpper Cretaceous of Antarctica. — In: Crame, J. A.(ed.), Origins and evolution of the Antarctic biota. —Geological Society Special Publication 47: 197–215.

Chippindale, P. T. & Wiens, J. J. 1994: Weighting,partitioning, and combining characters in phylogeneticanalysis. — Systematic Biology 43(2): 278–287.

Conybeare, W. D. 1822: Additional notices on thefossil genera Ichthyosaurus and Plesiosaurus. —Transactions of the Geological Society of London2(1):103–123.

Conybeare, W. D. 1824: On the discovery of an almostperfect skeleton of the Plesiosaurus. — Transactionsof the Geological Society of London 1: 382–389.

Cope, E. D. 1869: Synopsis of the extinct Batrachia,Reptilia and Aves of North America. — Transac-tions of the American Philosophical Society (newseries) 14: 1–252.

Cragin, F. 1888: Preliminary description of a new or littleknown saurian from the Benton of Kansas. — Ameri-can Geology 2: 404–407.


Cruickshank, A. R. I. 1994a: Cranial anatomy of theLower Jurassic pliosaur Rhomaleosaurus megaceph-alus (Stutchbury) (Reptilia: Plesiosauria.). — Philo-sophical Transactions of the Royal Society of LondonB 343: 247–260.

Cruickshank, A. R. I. 1994b: A juvenile plesiosaur (Ple-siosauria: Reptilia) from the Lower Lias (Hettangian:Lower Jurassic) of Lyme Regis, England: a pliosau-roid-plesiosauroid intermediate? — Zoological Jour-nal of the Linnean Society 112: 151–178.

Cruickshank, A. R. I. 1997: A Lower Cretaceous pliosau-rid from South Africa. — Annals of the South AfricanMuseum 105(2): 207–226.

de Blainville, H. D. 1835: Description de quelques espèc-es de reptiles de la Californie, précédée de l’analysed’un système general d’Erpetologie et d’Amphibio-logie. — Nouvelles Annales du Muséum (National)d’History Naturaelle, Paris 4:233–296.

de Braga, M. & Rieppel, O. 1997: Reptile phylogeny andthe interrelationships of turtles. — Zoological Jour-nal of the Linnean Society 120: 281–354.

De la Beche, H. T. & Conybeare, W. D. 1821: Notice ofthe discovery of a new fossil animal, forming a linkbetween the Ichthyosaurus and the crocodile, togeth-er with general remarks on the osteology of Ichthyo-saurus. — Transactions of the Royal Society ofLondon 5: 559–594.

Delair, J. B. 1959: The Mesozoic reptiles of Dorset. PartII. — Proceedings of the Dorset Natural History andArchaeological Society 80: 52–90.

Druckenmiller, P. S. 1999: Osteology and relationshipsof a new plesiosaur from the Thermopolis Shale ofMontana. — Journal of Vertebrate Paleontology19(3) suppl.: 42A.

Edinger, T. 1935: Pistosaurus. — Neues Jahrbuch fürMineralogie, Geologie, und Paläontologie 74:321–359.

Fraas, E. 1910: Plesiosaurier aus dem oberen Lias vonHolzmaden. — Palaeontographica 57: 105–140.

Gray, J. E. 1825: A synopsis of the genera of reptiles andAmphibia, with a description of some new species.— Annals of Philosophy 26: 193–217.

Halstead, L. B. 1989: Plesiosaur locomotion. — Quarter-ly Journal of the Geological Society of London 146:37–40.

Hampe, O. 1992: Ein großwüchsiger Pliosauride (Reptil-ia: Plesiosauria) aus der Unterkreide (oberes Aptium)von Kolumbien. — Courier Forsch.-Inst. Sencken-berg 145: 1–32.

Kuhn, O. 1961: Die Familien der rezenten und fossilenAmphibien und Reptilien. — Verlagshaus Meisen-bach, Bamberg, Germany.

Lee, M. S. Y. 1997 Reptile relationships turn turtle. —Nature 389: 245–246.

Linder, H. 1913: Beiträge zur Kenntnis der Plesiosaurier-Gattungen Peloneustes und Pliosaurus, nebst An-hang: Über die beiden ersten Halswirbel der Plesio-saurier. — Geologie und Paläontologie Abhandlu-

gen, n. ser. 15(5): 339–409.Lingham-Soliar, T. 2000: Plesiosaur locomotion: is the

four-wing problem real or merely an atheoreticalexercise? — N. Jb. Geol. Paläont. Abh. 217(1): 45–87.

Longman, H. A. 1924: Some Queensland fossil vertebrates.— Memoirs of the Queensland Museum 8: 26–28.

Longman, H. A. 1930: Kronosaurus queenslandicus. Agiant Cretaceous pliosaur. — Memoirs of the Queens-land Museum 10: 1–7.

Lydekker, R. 1889a: On the generic position of the so-called Plesiosaurus indicus. — Geological Survey ofIndia 22(1): 49–51.

Lydekker, R. 1889b: On the remains and affinities of fivegenera of Mesozoic reptiles. — Quarterly Journal ofthe Geological Society of London 45: 41–59.

Massare, J. A. 1988: Swimming capabilities of Mesozoicmarine reptiles: implications for method of preda-tion. — Paleobiology 14(2): 187–205.

Merck, J. W. 1997: A phylogenetic analysis of theeuryapsid reptiles. — Journal of Vertebrate Paleon-tology 17(3) suppl.: 65A.

Meyer, H. v. 1839: Mitteilung an Professor Bronn gerich-tet. — Neues Jahrbuch für Mineralogie, Geognosie,Geologie und Petrefakten-Kunde 1839: 699–701.

Meyer, H. v. 1841: Thaumatosaurus oolithicus der fos-sile WunderSaurus aus dem Oolith. — Neues Jahr-buch für Mineralogie, Geologie, und Paläontologie1841: 176–184.

Meyer, H. v. 1842: Simosaurus, die Stumpfschnauze, einSaurier aus dem Muschelkalke von Luneville. —Neues Jahrbuch für Mineralogie, Geognosie, Geolo-gie und Petrefakten-Kunde 1842: 184–197.

Newman, B. & Tarlo, L. B. H. 1967: A giant marine reptilefrom Bedfordshire. — Animals, London 10(2): 61–63.

O’Keefe, F. R. 2000: Phylogeny and convergence in thePlesiosauria (Reptilia: Sauropterygia). — Ph.D. the-sis, University of Chicago, Chicago IL.

O’Keefe, F. R. 2002: The evolution and functional mor-phology of plesiosaur and pliosaur morphotypes inthe Plesiosauria (Reptilia: Sauropterygia). — Paleo-biology 28(1). [In press].

Osborn, H. F. 1903: The reptilian subclasses Diapsidaand Synapsida and the early history of the Diaptosau-ria. — Memoirs of the American Museum of NaturalHistory 1: 449–507.

Owen, R. 1838: A description of Viscount Cole’s speci-men of Plesiosaurus macrocephalus (Conybeare). —Proceedings of the Geological Society of London 2:663–666.

Owen, R. 1840: Report on British Fossil Reptiles, Part I.— Reports of the British Association for the Ad-vancement of Science, London: 42–126.

Owen, R. 1841: Report on British fossil reptiles, Part II.— Reports of the British Association for the Ad-vancement of Science, London: 60–65.

Owen, R. 1860: On the orders of fossil and RecentReptilia, and their distribution through time. — Re-port of the British Association for the Advancement


of Science 29: 153–166.Owen, R. 1865: A monograph on the fossil Reptilia of the

Liassic formations, Part 3. — Palaeontological Soci-ety of London, London.

Persson, P. O. 1963: A revision of the classification of thePlesiosauria with a synopsis of the stratigraphical andgeological distribution of the group. — Lunds Univer-sites Årsskrift N. F. Ard. 2 Bd. 59 Num. 1: 1–57.

Phillips, J. 1871: Geology of Oxford and the valley of theThames. — Oxford University Press, Oxford, England.

Reisz, R. R. 1981: A diapsid reptile from the Pennsylva-nian of Kansas. — Special Publication of the Muse-um of Natural History, University of Kansas 7: 1–74.

Rieppel, O. 1994a: Osteology of Simosaurus gaillardotiand the relationships of stem-group Sauropterygia.— Fieldiana Geology, New Series 28:1–85.

Rieppel, O. 1994b: The braincases of Simosaurus andNothosaurus: monophyly of the Nothosauridae (Rep-tilia: Sauropterygia). — Journal of Vertebrate Pale-ontology 14(1): 9–23.

Rieppel, O. 1997a: Introduction to Sauropterygia. — In:Callaway, J. M. & Nicholls, E. L. (eds.), Ancientmarine reptiles: 107–119. Academic Press, San Di-ego, California.

Rieppel, O. 1997b: Revision of the sauroptergian reptilegenus Cymatosaurus v. Fritsch, 1894, and the rela-tionships of Germanosaurus Nopcsa 1928, from theMiddle Triassic of Europe. — Fieldiana (Geology)N. S. 36: 1–38.

Rieppel, O. 1998: Corosaurus alcovensis Case and thephylogenetic interrelationships of Triassic stem-groupSauropterygia. — Zoological Journal of the LinneanSociety 124: 1–41.

Rieppel, O. 1999: Phylogeny and paleobiogeography ofTriassic Sauropterygia: problems solved and unre-solved. — Palaeogeography, Palaeoclimatology, Pal-aeoecology 153: 1–15.

Rieppel, O. 2000: Sauropterygia I. Placodontia, Pachyp-leurosauria, Nothosauroidea, Pistosauroidea. — In:Kuhn, O. & Wellnhofer, P. (eds.), Encylopedia ofpaleoherpetology, Part 12A: 1–134. Verlag Dr. Frie-drich Pfeil, München, Germany.

Rieppel, O. & deBraga, M. 1996: Turtles as diapsidreptiles. — Nature 384: 453–455.

Rieppel, O. & Hagdorn, H. 1997: Paleobiogeography ofMiddle Triassic Sauropterygia in central and westernEurope. — In: Callaway, J. M. & Nicholls, E. L.(eds.), Ancient marine reptiles: 121–144. AcademicPress, San Diego, California.

Rieppel, O. C. & Reisz, R. R. 1999: The origin and earlyevolution of turtles. — Annual Review of Ecologyand Systematics 30: 1–22.

Rieppel, O. & Werneburg 1998: A new species of thesauropterygian Cymatosaurus from the lowerMuschelkalk of Thuringia, Germany. — Palaeontol-ogy 41(4): 575–589.

Rieppel, O. & Wild, R. 1996: A revision of the genusNothosaurus (Reptilia: Sauropterygia) from the Ger-

man Triassic, with comments on the status of Con-chiosaurus clavatus. — Fieldiana (Geology) N. S.34: 1–82.

Romer, A. S. 1956: Osteology of the Reptiles. — Univer-sity of Chicago Press, Chicago, Illinois.

Romer, A. S. 1966: Vertebrate paleontology, 3rd ed. —University of Chicago Press, Chicago, Illinois.

Sander, P. M., Rieppel, O. C. & Bucher, H. 1997: A newpistosaurid (Reptilia: Sauropterygra) from the Mid-dle Triassic of Nevada and its implications for theorigins of plesiosaurs. — Journal of VertebratePaleontology 17(3): 526–533.

Sauvage, H. E. 1873: Notes sur les reptiles fossiles.— Bulletin of the Geological Society of France1(3): 365–380.

Seeley, H. 1874a: On Muraenosaurus leedsi, a plesiosau-rian from the Oxford Clay. — Quarterly Journal ofthe Geological Society, London 30: 197–208.

Seeley, H. 1874b: Note on some generic modifications ofthe plesiosaurian pectoral arch. — Quarterly Journalof the Geological Society of London 30: 436–449.

Seeley, H. 1892: The nature of the shoulder girdle andthe clavicular arch in Sauropterygia. — Proceedingsof the Royal Society of London 51: 119–151.

Sereno, P. C. 1998: A rationale for phylogenetic defini-tions, with application to the higher-level taxonomyof Dinosauria. — Neues Jahrbuch Geol. Palaönt.Abh. 210(1):41–83.

Sollas, W. J. 1881: On a new species of Plesiosaurus (P.conybeari) from the Lower Lias of Charmouth; withobservations on P. megacephalus, Stutchbury, and P.brachycephalus, Owen. — Quarterly Journal of theGeological Society of London 37: 440–480.

Storrs, G. W. 1991: Anatomy and relationships of Coro-saurus alcovensis (Diapsida: Sauropterygia) and theTriassic Alcova Limestone of Wyoming. — Bulletinof the Peabody Museum of Natural History 44: 1–151.

Storrs, G. W. 1993: Function and phylogeny in saurop-terygian (Diapsida) evolution. — American Journalof Science 293 A: 63–90.

Storrs, G. W. 1997: Morphological and taxonomic clarifi-cation of the genus Plesiosaurus. — In: Callaway, J.M. & Nicholls, E. L. (eds.), Ancient marine reptiles:145–190. Academic Press, San Diego, California.

Storrs, G. W. 1999: An examination of Plesiosauria(Diapsida: Sauropterygia) from the Niobrara Chalk(Upper Cretaceous) of central North America. —University of Kansas Paleontological Contributions11: 1–15.

Storrs, G. W. & Taylor, M. A. 1996: Cranial anatomy of anew plesiosaur genus from the lowermost Lias, (Rhae-tian/Hettangian) of Street, Somerset, England. —Journal of Vertebrate Paleontology 16(3): 403–420.

Stutchbury, S. 1846: Description of a new species ofPlesiosaurus, in the museum of the Bristol Institu-tion. — Quarterly Journal of the Geological Societyof London 2: 411–417.

Sues, H. D. 1987: Postcranial skeleton of Pistosaurus and


interrelationships of the Sauropterygia. — Zoologi-cal Journal of the Linnean Society 90: 109–131.

Swinton, W. E. 1930: Preliminary account of a newgenus and species of plesiosaur. — Annals andMagazine of Natural History 6(10): 206–209.

Swofford, D. L. & Begle, D. P. 1993: PAUP: Phyloge-netic analysis using parsimony, version 3.1.1. —Laboratory of Molecular Systematics, SmithsonianInstitution, Washington, D.C.

Tarlo, L. B. 1960: A review of the Upper Jurassicpliosaurs. — Bulletin of the British Museum (NaturalHistory) Geology 4(5): 147–189.

Taylor, M. A. 1992a: Taxonomy and taphonomy ofRhomaleosaurus zetlandicus (Plesiosauria, Reptilia)from the Toarcian (Lower Jurassic) of the YorkshireCoast. — Proceedings of the Yorkshire GeologicalSociety 49: 49–55.

Taylor, M. A. 1992b: Functional anatomy of the head ofthe large aquatic predator Rhomaleosaurus zetlandi-cus (Plesiosauria, Reptilia) from the Toarcian (LowerJurassic) of the Yorkshire Coast. — PhilosophicalTransactions of the Royal Society of London B: 335:247–280.

Taylor, M. A. 1997: Before the dinosaur: the historicalsignificance of the fossil marine reptiles. — In:Callaway, J. M. & Nicholls, E. L. (eds.), Ancientmarine reptiles: xix–xlvi. Academic Press, San Di-ego, California.

Taylor, M. A. & Cruickshank, A. R. I. 1993: Cranialanatomy and functional morphology of Pliosaurusbrachyspondylus (Reptilia: Plesiosauria) from theUpper Jurassic of Westbury, Wiltshire. — Philo-sophical Transactions of the Royal Society of LondonB 341: 399–418.

Vaughn, P. P. 1955: The Permian reptile Araeoscelisrestudied. — Bulletin of the Museum of ComparativeZoology 113(5): 305–467.

von Fritsch, K. 1894: Beitrag zur Kenntnis der Saurierdes Halle’schen unteren Muschelkalkes. — Abhand-lungen der Naturforschenden Gesellschaft zu Halle20: 273–302.

Watson, D. W. S. 1911: Upper Lias Reptilia, Part 3.Microcleidus macropterus (Seeley) and the limbs ofMicrocleidus homalospondylus (Owen). — Memoirsof the Manchester Literary and Philosophical Society55(17): 1–9.

Wegner, T. 1914: Brancasaurus brancai n. g. n. sp., einElasmosauride aus Wealden Westfalens. — In: Bran-

ca-Festschrift: 235–302. Verlag von Gebrüder Born-traeger, Leipzig, Germany.

Welles, S. P. 1943: Elasmosaurid plesiosaurs with de-scription of new material from California and Colo-rado. — Memoirs of the University of California 13:125–254.

Welles, S. P. 1949: A new elasmosaur from the EagleFord Shale of Texas. — Fondren Science Series,Southern Methodist University 1: 1–28.

Welles, S. P. 1952: A review of the North AmericanCretaceous elasmosaurs. — University of CaliforniaPublications in the Geological Sciences 29: 47–144.

Welles, S. P. 1962: A new species of elasmosaur from theAptian of Columbia and a review of the Cretaceousplesiosaurs. — University of California Publicationsin the Geological Sciences 44(1): 1–96.

White, T. E. 1935: On the skull of Kronosaurus queens-landicus Longman. — Occasional Papers of theBoston Society of Natural History 8: 219–228.

White, T. E. 1940: Holotype of Plesiosaurus longirostrusBlake and the classification of the plesiosaurs. —Journal of Paleontology 14(5): 451–467.

Williston, S. W. 1890: A new plesiosaur from the Nio-brara Cretaceous of Kansas. — Transaction of theKansas Academy of Sciences, 12: 174–178.

Williston, S. W. 1903: North American plesiosaurs, Part1. — Field Columbian Museum Publication (Geolo-gy) 73(2): 1–77.

Williston, S. W. 1906: North American plesiosaurs:Elasmosaurus, Cimoliasaurus, and Polycotylus.— American Journal of Science, Fourth Series21(123): 221–236.

Williston, S. W. 1907: The skull of Brachauchenius, withobservations of the relationships of the plesiosaurs.— Proceedings of the National Museum 32(1540):477–493.

Williston, S. W. 1908: North American plesiosaurs. Tri-nacromerum. — Journal of Geology, Chicago 16:715–736.

Williston, S. W. 1914: Water reptiles of the past andpresent. — University of Chicago Press, Chicago,Illinois.

Williston, S. W. 1925: The osteology of the reptiles. —Cambridge University Press, Cambridge, Massachu-setts.

Zittel, K. A. 1887: Handbuch der Paläontologie. I.Paläozoologie. III. Amphibien, Reptilien, Vögel. —Oldenbourg, München und Leipzig.


Ap

pen

dix

1. C

hara

cter

s, s

tate

defi

nitio

ns, r

efer

ence

s, a

nd c

omm

ents

for

the

clad

istic

cha

ract

ers

used

in th

is p

aper

. For

dis

cuss

ion

see

text

.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—1

Mor

phom

etric

Rel

ativ

e sk

ull l

engt

hP

rimiti

ve/ ‘

noth

osau

rian’

(0)

,B

row

n 19

81, c

har.

2S

core

d fr

om m

orph

omet

ric d

ata

in O

’Kee

fe 2

000:

larg

e (1

), s

mal

l (2)

chap

ter

3. T

hala

ssio

drac

on is

prim

itive

for

this

char

acte

r, a

s ar

e m

ost r

hom

aleo

saur

ids.

2M

orph

omet

ricR

elat

ive

neck

leng

thP

rimiti

ve (

0), l

ong

(1),

sho

rt (

2)S

torr

s 19

91, c

har.

2S

core

d fr

om m

orph

omet

ric d

ata

in O

’Kee

fe 2

000:

chap

ter

3.

3M

orph

omet

ricR

elat

ive

leng

th o

fS

ubeq

ual (

0), i

schi

um lo

nger

(1)

,B

row

n 19

81, c

har.

29

Sco

red

from

mor

phom

etric

dat

a in

O’K

eefe

200

0:is

chiu

m/p

ubis

pubi

s lo

nger

(2)

chap

ter

3.

4M

orph

omet

ricR

elat

ive

leng

th o

fS

ubeq

ual (

0), c

orac

oid

long

er, (

1)W

elle

s 19

62S

core

d fr

om m

orph

omet

ric d

ata

in O

’Kee

fe 2

000:

scap

ula/

cora

coid

chap

ter

3; d

eriv

ed e

lasm

osau

rs a

re th

e on

lypl

esio

saur

s in

whi

ch th

is r

atio

is s

ubeq

ual.

5M

orph

omet

ricR

elat

ive

leng

th o

fS

ubeq

ual (

0), h

umer

us lo

nger

(1)

,B

row

n 19

81, c

har.

32

Sco

red

from

mor

phom

etric

dat

a in

O’K

eefe

200

0:hu

mer

us/fe

mur

fem

ur lo

nger

(2)

chap

ter

3.

6M

orph

omet

ricP

reor

bita

l and

Sub

equa

l (0)

, lon

ger

preo

rbita

l (1)

,R

iepp

el 1

994a

, 199

7b,

Thi

s ra

tio is

con

trol

led

by th

e le

ngth

of t

he s

nout

post

orbi

tal s

kull

leng

thsh

orte

r (2

)ch

ars.

9, 1

2re

lativ

e to

the

tem

pora

l fen

estr

a an

d su

spen

soriu

m.

7M

orph

omet

ricF

in a

spec

t rat

ioH

igh

(0),

low

(1)

Sco

red

from

mor

phom

etric

dat

a in

O’K

eefe

200

0:ch

apte

r 3;

the

two

stat

es a

re b

ased

on

a br

eak

inth

e di

strib

utio

n of

asp

ect r

atio

dat

a.

8S

kull

shap

eE

long

ate

rost

rum

Abs

ent (

0), p

rem

axill

a on

ly (

1),

Par

tially

mod

ified

from

Sta

te o

ne is

defi

ned

as a

long

sno

ut w

ith li

ttle

or n

ove

ry lo

ng w

ith m

axill

a in

clud

ed (

2),

Tar

lo 1

960

incr

ease

in s

nout

leng

th p

oste

rior

to p

rem

axill

a/el

onga

te a

nd h

oop-

like/

unco

nstr

icte

d (3

)m

axill

a su

ture

. Sta

te tw

o in

clud

es le

ngth

enin

g of

max

illa;

sta

te th

ree

desc

ribes

the

larg

e, u

ncon

stric

ted

snou

ts o

f Kim

mer

osau

rus

and

rela

ted

taxa

. Thi

sch

arac

ter

is o

rder

ed, u

sing

the

char

acte

r st

ate

tree

(0(3

)(1,

2)).

Fig

s. 7

, 2 a

nd 1

1.

9S

kull

shap

eC

onst

ricte

d sn

out

Unc

onst

ricte

d (0

), c

onst

ricte

d at

Rie

ppel

199

4a, 1

997b

,C

onst

rictio

n at

the

prem

axill

a/m

axill

a su

ture

is c

omm

onm

axill

a/pr

emax

illa

sutu

re(1

), s

econ

dS

torr

s 19

91, c

hars

. 3, 1

3in

long

-sno

uted

sau

ropt

eryg

ians

. Sta

te tw

o de

scrib

esco

nstr

ictio

n in

max

illa

(2)

the

cond

ition

of L

iopl

euro

don ,

whi

ch h

as a

sec

ond,

mor

e po

ster

ior

cons

tric

tion

(And

rew

s 19

13).

Thi

sch

arac

ter

is o

rder

ed b

ecau

se th

e se

cond

con

stric

tion

neve

r oc

curs

in th

e ab

senc

e of

the

first

. Fig

. 11.

Con

tinue

d

O’Keefe • ACTA ZOOL. FENNICA No. 21336A

pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—10

Sku

ll sh

ape

Tem

pora

l em

argi

natio

nP

rese

nt (

0), a

bsen

t(1)

Sto

rrs

1991

, cha

r. 6

Ara

eosc

elis

has

a s

trai

ght s

kul l

mar

gin

belo

w th

ete

mpo

ral f

enes

tra;

mos

t sau

ropt

eryg

ians

hav

e an

emar

gina

tion

here

. The

con

ditio

n in

ple

sios

aurs

isdi

fficu

lt to

det

erm

ine,

as

the

varia

tion

is c

ontin

uos;

my

crite

rion

for

the

pres

ence

of e

mar

gina

tion

is a

nex

cava

ted

vent

ro-la

tera

l em

baym

ent o

f the

squa

mos

al. B

y th

is c

riter

ion

mos

t ple

sios

aurs

hav

ete

mpo

ral e

mar

gina

tion.

Fig

. 14.

11S

kull

roof

Dor

so-m

edia

l pro

cess

Con

tact

s fr

onta

l (0)

, con

tact

s pa

rieta

lA

ndre

ws

1911

bT

he p

rem

axi l l

ae s

end

dors

o-m

edia

l pro

cess

esof

pre

max

i l la

at p

inea

l for

amen

(2),

con

tact

s an

terio

rpo

ster

iorly

acr

oss

the

skul

l roo

f in

mos

tex

tens

ion

of th

e pa

rieta

l (1)

plio

saur

omor

ph ta

xa a

nd s

ome

elas

mos

aurs

, and

thes

e pr

oces

ses

may

mee

t the

par

ieta

ls in

var

ious

way

s. W

hile

thes

e pr

oces

ses

sepa

rate

the

fron

tals

on

the

dors

al m

idlin

e, th

e fr

onta

ls m

ay r

etai

n a

mid

line

sutu

re b

enea

th th

e pr

emax

illae

(A

ndre

ws

1911

b).

Fig

s. 5

and

10.

12S

kull

roof

Pre

max

illa/

exte

rnal

Pre

sent

(0)

, abs

ent (

1)C

onta

ct o

f the

pre

max

illa

with

the

exte

rnal

nar

is is

naris

con

tact

prim

itive

, occ

urrin

g in

Ara

eosc

elis

. Thi

s co

ntac

t is

lost

in s

ome

plio

saur

s. F

ig. 1

0.

13S

kull

roof

Dor

sal m

edia

n fo

ram

enA

bsen

t (0)

, pre

sent

(1)

Cru

icks

hank

199

7A

sha

llow

dep

ress

ion

occu

rs in

the

dors

o-m

edia

lpr

oces

ses

of th

e pr

emax

illae

in s

ome

rhom

aleo

saur

ids.

14S

kull

roof

Fro

ntal

s pa

ired/

fuse

dP

aire

d (0

), fu

sed

(1)

Rie

ppel

199

4a, 1

997b

,F

usio

n of

the

fron

tals

on

the

skul

l roo

f can

onl

y be

in a

dult

char

s. 1

1, 1

4sc

ored

for

taxa

in w

hich

the

fron

tal m

idlin

e su

ture

isvi

sibl

e; th

is c

hara

cter

is th

eref

ore

inap

plic

able

for

taxa

in w

hich

the

dors

o-m

edia

l pro

cess

es o

f the

prem

axill

ae r

each

the

parie

tals

.

15S

kull

roof

Par

ieta

ls p

aire

d or

Pai

red

(0),

fuse

d po

ster

iorly

(1)

, fus

ed (

2)R

iepp

el 1

997b

, cha

r. 1

7F

usio

n of

the

parie

tals

on

the

dors

al m

idlin

e is

an

fuse

d in

adu

ltim

port

ant c

hara

cter

in b

asal

‘not

hosa

urs’

; how

ever

this

cha

ract

er is

diffi

cult

to s

core

in ta

xa w

here

the

parie

tal s

kull

tabl

e is

a n

arro

w s

agitt

al c

rest

, whi

ch is

vuln

erab

le to

bre

akag

e. I

have

ther

efor

e sc

ored

this

char

acte

r as

inap

plic

able

for

ples

iosa

urs.

16S

kll

fF

tl

ithith

tW

itht

(0)

Ri

l199

419

97b

Adi

t it

tl

tl

f th

ft

l


Sku

ll ro

ofF

ront

al w

ith o

r w

ithou

tW

ithou

t pro

cess

es (

0),

Rie

ppel

199

4a, 1

997b

,A

dis

tinct

pos

tero

-late

ral p

roce

ss o

f the

fron

tal o

ccur

sdi

stin

ct p

oste

ro-la

tera

lw

ith p

roce

sses

(1)

char

s. 1

2, 1

5; S

torr

s 19

91in

the

pist

osau

roid

s C

ymat

osau

rus

and

Pis

tosa

urus

. It

proc

ess

char

. 30

also

occ

urs

in v

ery

prim

itive

ple

sios

aurs

suc

h as

Tha

lass

iodr

acon

and

Ple

sios

auru

s . F

ig. 4

.

17S

kull

roof

Pos

torb

ital b

arB

oth

po a

nd p

of h

ave

orbi

tal c

onta

ct (

0),

In s

ome

elas

mos

aurs

, the

pos

tfron

tal i

s co

nfine

d to

fron

tal/p

o su

ture

exc

lude

s po

f fro

mth

e in

side

of t

he te

mpo

ral f

enes

tra

and

excl

uded

from

orbi

t mar

gin

(1)

the

orbi

t by

a fr

onta

l-pos

torb

ital s

utur

e.

18S

kull

roof

Fro

ntal

ent

ers

mar

gin

Doe

s no

t (0)

,R

iepp

el 1

994a

, 199

7b,

of te

mpo

ral f

enes

tra

does

nar

row

ly (

1)ch

ars.

13,

16

19S

kull

roof

Fro

ntal

con

tact

sD

oes

cont

act (

0),

The

fron

tal c

onta

cts

the

exte

rnal

nar

is in

som

eex

tern

al n

aris

does

not

con

tact

(1)

plio

saur

s. F

ig. 1

0.

20S

kull

roof

Pin

eal f

oram

en lo

catio

nM

iddl

e of

par

ieta

l (0)

, ant

erio

r (1

)R

iepp

el 1

994a

, 199

7b,

The

mov

emen

t of t

he p

inea

l for

amen

to th

e an

terio

r of

char

s. 1

5, 1

8, a

lso

the

parie

tal s

kul l

tabl

e is

a c

hara

cter

sha

red

by th

eS

ues

1987

pist

osau

rids

and

ples

iosa

urs.

Som

e w

orke

rs (

Wel

les

1962

, Car

pent

er 1

996)

con

tend

that

the

pine

alfo

ram

en is

lost

in s

ome

taxa

; It i

s pr

esen

t in

all t

axa

Iha

ve e

xam

ined

. Fig

s. 4

and

5.

21S

kull

roof

Pin

eal f

oram

enN

ot b

orde

red

by fr

onta

l (0)

,A

ndre

ws

1911

bIn

Pel

oneu

stes

(an

d po

ssib

ly o

ther

plio

saur

s kn

own

bord

ered

ant

erio

rlybo

rder

ed b

y fr

onta

l (1)

from

infe

rior

mat

eria

l), th

e fr

onta

ls fo

rm p

art o

f the

by fr

onta

ls o

n do

rsal

ante

rior

mar

gin

of th

e pi

neal

fora

men

, but

onl

ysk

ull s

urfa

cebe

neat

h th

e pr

emax

illae

. Tax

a w

ere

scor

ed a

s de

rived

for

this

cha

ract

er o

nly

if th

e fr

onta

l for

med

par

t of t

hem

argi

n on

the

dors

al s

kull

roof

, as

is th

e ca

se in

som

eel

asm

osau

rs a

nd c

rypt

oclid

ids,

but

not

in p

liosa

urs.

22S

kull

roof

Pre

fron

tal p

rese

ntP

rese

nt (

0), a

bsen

t (1)

or a

bsen

t

23S

kull

roof

Acc

esso

ry fe

nest

raA

bsen

t (0)

, pre

sent

(1)

Car

pent

er 1

996

Car

pent

er d

escr

ibed

this

feat

ure

in th

e po

lyco

tylid

sab

ove

orbi

tsD

olic

hory

ncho

ps a

nd T

rinac

rom

erum

; I w

as u

nabl

e to

confi

rm it

s pr

esen

ce in

eith

er ta

xon.

The

orb

ital r

egio

nin

pol

ycot

ylid

s is

del

icat

e an

d lia

ble

to b

reak

age.

24S

kull

roof

Fro

ntal

pro

cess

Abs

ent (

0), p

rese

nt (

1)C

arpe

nter

199

6C

arpe

nter

des

crib

ed th

is fe

atur

e in

the

poly

coty

lids

proj

ects

into

orb

itD

olic

hory

ncho

ps a

nd T

rinac

rom

erum

; It i

s pr

esen

t in

both

taxa

alth

ough

pre

serv

atio

n of

the

feat

ure

is p

oor

due

to th

e de

licat

e na

ture

of t

he b

ones

in th

e or

bit r

egio

n.

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—25

Sku

ll ro

ofP

arie

tal s

kul l

tabl

eR

elat

ivel

y br

oad

(0),

con

stric

ted

(1),

Rie

ppel

199

4a, 1

997b

,P

osse

ssio

n of

a s

harp

ly k

eele

d sa

gitta

l cre

st is

asa

gitta

l cre

st (

2)ch

ars.

16,

19;

feat

ure

shar

ed b

y al

l ple

sios

aurs

and

Pis

tosa

urus

. The

Bro

wn

1981

, cha

r. 9

sagi

ttal c

rest

is th

e cu

lmin

atio

n of

a tr

end

of s

kul l

tabl

ena

rrow

ing

in th

e pi

stos

auro

ids.

Fig

s. 1

4 an

d 18

.

26S

kull

roof

Squ

amos

al p

rodu

ces

No

med

ial p

roce

ss (

0), m

edia

lT

he s

utur

e of

the

quad

rate

with

the

squa

mos

al is

long

, thi

n pr

oces

spr

oces

s an

d so

cket

-l ike

squ

amos

al (

1)pr

omin

ent a

nd r

obus

t in

all p

lesi

osau

rs. I

n so

me

cove

ring

quad

rate

plio

saur

s th

e sq

uam

osal

has

des

cend

ing

late

ral a

ndla

tera

l lym

edia

l pro

cess

es o

n ei

ther

sid

e of

the

quad

rate

inoc

cipi

tal v

iew

, for

min

g a

sock

et th

at a

ccep

ts th

equ

adra

te. I

n so

me

ples

iosa

uroi

ds th

e la

tera

l pro

cess

is m

uch

long

er th

an th

e m

edia

l pro

cess

, the

late

ral

proc

ess

reac

hes

alm

ost t

o th

e ja

w a

rtic

ulat

ion,

and

the

sutu

re is

less

soc

ket-

like.

The

pol

ycot

ylid

s po

sses

sth

e se

cond

type

of s

utur

e.

27S

kull

roof

Squ

amos

al d

orsa

lN

o su

ture

(0)

, mee

t in

arch

at m

idlin

e (1

)S

ues

1987

,A

n oc

cipi

tal a

rch

form

ed b

y a

med

ian

squa

mos

alpr

oces

ses

Rie

ppel

199

7b, c

har.

36

sutu

re is

cha

ract

eris

tic o

f all

ples

iosa

urs

and

Pis

tosa

urus

. Cym

atos

auru

s is

inte

rmed

iate

in h

avin

g a

very

nar

row

sep

arat

ion

of th

e sq

uam

osal

s in

occ

ipita

lvi

ew (

see

Rie

ppel

199

8b).

Fig

s. 5

and

10.

28S

kull

roof

Squ

amos

al/p

osto

rbita

lC

onta

ct (

0), n

o co

ntac

t (1)

The

squ

amos

al o

ften

cont

acts

the

post

orbi

tal w

ithin

cont

act

the

tem

pora

l fen

estr

a on

the

rear

of t

he p

osto

rbita

lba

r; h

owev

er, t

his

char

acte

r co

ncer

ns o

nly

the

mar

gin

of th

e te

mpo

ral f

enes

tra

in la

tera

l vie

w. C

onta

ct o

f the

two

bone

s ex

clud

es th

e ju

gal f

rom

the

mar

gin

of th

ete

mpo

ral f

enes

tra.

Fig

. 14.

29S

kull

roof

Juga

l/squ

amos

alN

o co

ntac

t (0)

, con

tact

(1)

Con

tact

of t

he ju

gal a

nd s

quam

osal

is c

hara

cter

istic

of

cont

act

all p

lesi

osau

rs a

nd C

ymat

osau

rus.

Fig

. 14.

30S

kull

roof

Juga

l ext

ends

Ant

erio

r m

argi

n (0

), m

iddl

e of

orb

it (1

),R

iepp

el 1

994a

, 199

7b,

Fig

s. 4

, 5 a

nd 1

0.an

terio

rly a

long

ven

tral

rest

ricte

d to

pos

terio

r m

argi

n (2

)ch

ars.

20,

23;

Sto

rrs

1991

,or

bita

l mar

gin

char

. 24;

Cru

icks

hank

1994

b, c

har.

2

31S

kull

roof

Juga

l con

tact

sC

onta

cts

orbi

t (0)

, exc

lude

dM

odifi

ed fr

om S

torr

s 19

91,

orbi

t mar

gin

by p

o/m

con

tact

(1)

char

. 24

32S

kull

roof

Juga

l/pre

fron

tals

utur

eA

bsen

t(0)

pres

ent(

1)M

any

plio

saur

sha

vea

sutu

rebe

twee

nth

epr

efro

ntal


32S

kull

roof

Juga

l/pre

fron

tal s

utur

eA

bsen

t (0)

, pre

sent

(1)

Man

y pl

iosa

urs

have

a s

utur

e be

twee

n th

e pr

efro

ntal

ante

rior

to o

rbit

and

juga

l ant

erio

r to

the

orbi

t, ex

clud

ing

the

max

illa

from

the

orbi

t mar

gin.

The

juga

l ext

ends

forw

ard

and

med

ially

aro

und

the

orbi

t to

mee

t the

pre

fron

tal.

The

pres

ence

of t

he ju

gal i

n th

is p

ositi

on h

as b

een

inte

rpre

ted

as a

lacr

imal

by

And

rew

s (1

913)

, and

Tay

lor

and

Cru

icks

hank

(19

93);

how

ever

the

lacr

imal

is lo

st in

bas

al s

auro

pter

ygia

ns. F

ig. 1

0.

33S

kull

roof

Juga

l for

ms

narr

ow b

arD

oes

not (

0), d

oes

(1)

Cru

icks

hank

199

4b,

As

reco

nstr

ucte

d by

Bro

wn

and

Cru

icks

hank

(19

94),

betw

een

orbi

t and

char

. 2an

d B

row

n (1

981)

, the

che

ek r

egio

n in

cry

ptoc

l idid

s is

tem

pora

l em

argi

natio

nre

duce

d, s

o th

at th

e ju

gal i

s th

e so

le e

lem

ent b

etw

een

the

tem

pora

l em

argi

natio

n an

d th

e or

bit.

Thi

s ar

ea is

very

frag

i le a

nd g

ener

ally

not

pre

serv

ed in

the

cryp

tocl

idid

s. T

he a

pom

orph

ic c

ondi

tion

of th

e ch

eek

in p

olyc

otyl

ids

is v

ery

sim

ilar

to th

is c

ondi

tion.

Fig

. 18.

34S

kull

roof

Qua

drat

ojug

alP

rese

nt (

0), a

bsen

t (1)

Rie

ppel

199

4a,

1997

b, c

hars

. 24,

29;

Sto

rrs

1991

, cha

r. 7

;S

ues

1987

35S

kull

roof

Nas

alN

ot r

educ

ed (

0), r

educ

ed (

1), a

bsen

t (2)

Rie

ppel

199

7b, c

har.

6;

Sto

rrs

(199

1) b

elie

ved

the

nasa

l los

t in

all p

lesi

osau

rs;

Sto

rrs

1991

, cha

r. 3

4;ho

wev

er it

is s

mal

l but

pre

sent

in P

elon

eust

es a

ndS

ues

1987

othe

r pl

iosa

urs,

as

wel

l as

Tha

lass

iodr

acon

. Fig

s. 4

and

10.

36S

kull

roof

Loca

tion

of n

asal

Beh

ind

exte

rnal

nar

is (

0), i

n fr

ont o

fT

his

char

acte

r is

app

licab

le o

nly

to ta

xa in

whi

ch th

ere

lativ

e to

ext

erna

lex

tern

al n

aris

(1)

nasa

ls a

re p

rese

nt. T

he d

eriv

ed s

tate

occ

urs

inna

risst

ratig

raph

ical

ly la

te p

liosa

urs

such

as

Bra

chau

chen

ius.

37S

kull

roof

Dis

tinct

gro

oves

Abs

ent (

0), p

rese

nt (

1)D

istin

ct g

roov

es in

the

max

illae

ant

erio

r to

and

lead

ing

ante

rior

to e

xter

nal

into

the

exte

rnal

nar

is a

re p

rese

nt in

som

ena

risrh

omal

eosa

urid

s an

d M

acro

plat

a .

38S

kull

roof

Nas

al e

nter

s m

argi

nD

o en

ter

(0),

do

not e

nter

(1)

Rie

ppel

199

7b, c

har.

7;

The

nas

als

are

redu

ced

and

do n

ot e

nter

the

exte

rnal

of e

xter

nal n

aris

Sto

rrs

1991

, cha

r. 3

6;na

ris in

Pis

tosa

urus

, and

ther

e is

som

e qu

estio

nS

ues

1987

whe

ther

the

nasa

ls a

re p

rese

nt in

this

taxo

n at

all

(Rie

ppel

199

4a).

Whe

n pr

esen

t, th

e na

sals

do

ente

rth

e m

argi

n of

the

exte

rnal

nar

is in

ple

sios

aurs

. Fig

s.4

and

10.

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—39

Sku

ll ro

ofP

refr

onta

l con

tact

sN

o co

ntac

t (0)

, con

tact

(1)

The

pre

fron

tal r

uns

from

the

ante

rior

mar

gin

of th

em

argi

n of

ext

erna

lor

bit t

o th

e po

ster

ior

mar

gin

of th

e ex

tern

al n

aris

inna

risP

lesi

osau

rus ,

ela

smos

aurid

s, c

rypt

ocl id

ids,

and

the

poly

coty

l ids.

Fig

s. 5

and

18.

40S

kull

roof

Pre

fron

tal a

ndF

ront

al e

xclu

ded

(0),

fron

tal e

nter

sR

iepp

el 1

997b

, cha

r. 1

0F

ig 1

0.po

stfr

onta

l exc

lude

mar

gin

(1)

fron

tal f

rom

dor

sal o

rbit

mar

gin

41S

kull

roof

Max

i l la/

squ

amos

alN

o co

ntac

t (0)

, con

tact

(1)

, exp

ande

dW

il lis

ton

1903

, p. 1

9T

his

char

acte

r de

scrib

es th

e co

ntac

t, or

lack

of

cont

act

post

erio

r fla

nge

(2)

cont

act,

betw

een

the

post

erio

r en

d of

the

max

i l la

and

the

squa

mos

al. S

tate

two

desc

ribes

the

cond

ition

inpo

lyco

tylid

s, in

whi

ch th

e m

axill

a fo

rms

a st

out,

expa

nded

con

tact

with

the

squa

mos

al.

42O

ccip

utE

xocc

ipita

l par

ticip

ates

Do

not p

artic

ipat

e (0

), d

o pa

rtic

ipat

e (1

)B

row

n 19

81, c

har.

7;

in fo

rmat

ion

of o

ccip

ital

Cru

icks

hank

199

4bco

ndyl

e

43O

ccip

utO

ccip

ital c

ondy

leH

emis

pher

ical

with

gro

ove

(0),

sho

rt w

ithB

row

n 19

81, c

har.

12

Bro

wn

(198

1) s

tres

ses

the

pres

ence

of a

gro

ove

mor

phol

ogy

no g

roov

e (1

)be

twee

n th

e oc

cipi

tal c

ondy

le a

nd th

e bo

dy o

f the

basi

occi

pita

l in

his

defin

ition

of t

his

char

acte

r. T

hegr

oove

is v

aria

bly

pres

ent a

nd p

roba

bly

varie

son

toge

netic

ally

; I h

ave

foun

d th

e sh

ape

of th

e co

ndyl

eto

be

mor

e re

liabl

e in

defi

ning

sta

tes.

Fig

. 11.

44O

ccip

utP

arao

ccip

ital

No

proc

ess/

occ

iput

pla

te-li

ke (

0),

Rie

ppel

199

7b, c

har.

31

A p

late

-like

occ

iput

is p

rese

nt in

mos

t bas

alpr

oces

s/ fo

rmat

ion

ofro

d-sh

aped

pro

cess

(1)

saur

opte

rygi

ans;

how

ever

, an

open

occ

iput

with

apo

stte

mpo

ral f

ossa

rod-

shap

ed p

arao

ccip

ital p

roce

ss o

ccur

s in

the

mar

gin

pist

osau

roid

s an

d al

l ple

sios

aurs

.

45O

ccip

utD

istin

ct s

quam

osal

With

out n

otch

(0),

with

not

ch (

1)R

iepp

el 1

997b

, cha

r. 3

2no

tch

for

artic

ulat

ion

ofpa

raoc

cipi

tal p

roce

ss

46O

ccip

utP

arao

ccip

ital p

roce

ssG

raci

le (

0), r

obus

t (1)

Bro

wn

1981

, cha

r. 1

1M

odifi

ed fr

om B

row

n (1

981)

. My

‘gra

cile

’ is

a co

mbi

natio

nm

orph

olog

yof

Bro

wn’

s ‘lo

ng’ a

nd ‘t

hin’

sta

tes,

whi

le m

y ‘ro

bust

’is

a c

ombi

natio

n of

his

‘sho

rt’ a

nd ‘t

hick

’ sta

tes.

The

para

occi

pita

l pro

cess

is r

obus

t in

true

plio

saur

s.


para

occi

pita

l pro

cess

is r

obus

t in

true

plio

saur

s.

47O

ccip

utP

arao

ccip

ital p

roce

ssS

quam

osal

exc

lusi

vely

(0)

, qua

drat

eLi

bone

ctes

has

sta

te tw

o, w

hile

the

artic

ulat

ion

of th

ear

ticul

atio

nex

clus

ivel

y (1

), b

oth

quad

rate

and

para

occi

pita

l pro

cess

shi

fts to

the

quad

rate

in s

ome

squa

mos

al (

2)cr

ypto

clid

ids

and

all p

olyc

otyl

ids.

48O

ccip

utV

entr

al e

xten

t of

Doe

s no

t ext

end

vent

ral t

o oc

cipi

tal

And

rew

s 19

10T

ricle

idus

and

the

poly

coty

l ids

have

long

par

aocc

ipita

lpa

raoc

cipi

tal p

roce

ssco

ndyl

e (0

), e

xten

ds p

ast c

ondy

le (

1)pr

oces

ses

whi

ch e

xten

d ve

ntra

l of t

he o

ccip

ital

cond

yle.

49O

ccip

utN

atur

e of

par

aocc

ipita

lN

o co

ntac

t (0)

, con

tact

at l

ater

alT

aylo

r an

d C

ruic

ksha

nk (

1993

) an

d T

aylo

r (1

992a

)pr

oces

s/ q

uadr

ate

artic

ulat

iono

nly

(1),

long

con

tact

alo

ngil l

ustr

ate

the

occi

put o

f Plio

saur

us a

ndpt

eryg

oid

flang

ebo

dies

of p

roce

sses

(2)

Rho

mal

eosa

urus

res

pect

ivel

y, d

epic

ting

a lo

ngco

ntac

tco

ntac

t (st

ate

two)

bet

wee

n th

e pa

raoc

cipi

tal p

roce

ssan

d th

e qu

adra

te fl

ange

of t

he p

tery

goid

in b

oth

taxa

. Idi

d no

t obs

erve

this

con

ditio

n; th

ese

taxa

pos

sess

stat

e on

e, a

s i l l

ustr

ated

by

Cru

icks

hank

(19

94a)

.

50O

ccip

utQ

uadr

ate

flang

e of

Qua

drat

e on

ly (

0), q

uadr

ate

and

Mod

ified

from

Bro

wn

The

squ

amos

al s

hare

s in

the

quad

rate

art

icul

atio

n of

pter

ygoi

d/ q

uadr

ate

squa

mos

al (

1)19

81, c

har.

10;

the

quad

rate

flan

ge o

f the

pte

rygo

id in

som

ear

ticul

atio

nC

ruic

ksha

nk 1

994b

,el

asm

osau

rs a

nd s

ome

plio

saur

s.ch

ar. 3

51O

ccip

utQ

uadr

ate

prod

uces

Pro

cess

abs

ent (

0), p

roce

ss p

rese

nt (

1)di

stin

ct p

roce

ss fo

rar

ticul

atio

n w

ithpt

eryg

oid

flang

e

52B

rain

case

Dor

sal w

ing

ofB

road

/ col

umna

r (0

), r

educ

ed (

1)R

iepp

el 1

997b

, cha

r. 3

9ep

ipte

rygo

id

53B

rain

case

Epi

pter

ygoi

d do

rsal

Con

tact

(0)

, no

cont

act (

1)Z

anon

unp

ublis

hed

proc

ess

cont

acts

parie

tal

54O

ccip

utQ

uadr

ate

emba

yed/

Mas

sive

qua

drat

e (0

), d

ishe

dM

ost p

lesi

osau

rs h

ave

a di

shed

or

emba

yed

ante

rior

dish

ed-s

hape

dan

terio

rly (

1)m

argi

n of

the

quad

rate

abo

ve th

e ja

w a

rtic

ulat

ion.

Thi

san

terio

rlyem

baym

ent i

s lo

st in

som

e el

asm

osau

rs.

55S

kull

roof

Pos

terio

r bu

lb fo

rmed

Abs

ent (

0), p

rese

nt (

1)T

he a

pex

of th

e sq

uam

osal

arc

h is

ela

bora

ted

into

aby

squ

amos

als

post

erio

rly-d

irect

ed b

ulb

in m

ost p

liosa

urs.

Fig

. 10.

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—56

Bra

inca

seS

upra

occi

pita

lR

ound

(0)

, med

ian

proc

ess

(1)

Zan

on u

npub

lishe

dT

he s

upra

occi

pita

l has

a m

edia

n pr

oces

s pr

ojec

ting

mor

phol

ogy

vent

ral ly

into

the

fora

men

mag

num

in m

ost

ples

iosa

urs.

Som

e ta

xa la

ck th

is fe

atur

e, a

lthou

gh it

isal

so d

elic

ate

and

l iabl

e to

bre

akag

e. T

hesu

prao

ccip

ital i

n ge

nera

l is

not b

ound

tigh

tly to

the

rest

of t

he s

kul l

and

is o

ften

lost

, at l

east

in L

ower

Jura

ssic

taxa

. Fig

. 5.

57P

alat

eS

hape

of t

he q

uadr

ate

Cur

ved

with

rai

sed

late

ral m

argi

n (0

),T

he q

uadr

ate

flang

e of

the

pter

ygoi

d is

a la

rge,

pter

ygoi

d fla

nge

stra

ight

and

nar

row

ing

(1),

sig

moi

d w

ithsi

gmoi

d st

ruct

ure

in m

any

plio

saur

s. T

his

cond

ition

isro

l led

late

ral m

argi

n (2

)de

rived

com

pare

d to

Tha

lass

iodr

acon

.A

ttenb

oros

auru

s di

spla

ys a

fairl

y in

term

edia

teco

nditi

on. F

ig. 1

1.

58P

alat

eS

quar

ed la

ppet

of

No

squa

red

lapp

et (

0), s

quar

ed la

ppet

(1)

Thi

s ch

arac

ter

desc

ribes

the

elab

orat

ion

of a

sm

all

pter

ygoi

d un

derli

esfla

nge

or la

ppet

from

the

body

of t

he p

tery

goid

, whi

chqu

adra

te p

tery

goid

unde

rlies

the

quad

rate

flan

ge o

f the

pte

rygo

id a

t its

flang

eor

igin

atio

n fr

om th

e pa

lata

l por

tion

of th

at b

one.

59B

rain

case

Sup

raoc

cipi

tal d

epth

/S

hallo

w (

0), d

eep

ante

ro-p

oste

riorly

/T

he s

upra

occi

pita

l in

Ple

sios

auru

s an

d ot

her

prim

itive

sigm

oid

sutu

resi

gmoi

d su

ture

with

exo

ccip

ital a

ndta

xa is

sha

llow

ant

ero-

post

erio

rly; t

he s

utur

e w

ith th

epr

ootic

(1)

exoc

cipi

tal i

s sh

ort a

nd th

e la

tera

l con

tact

with

the

proo

tic is

sm

all.

In o

ther

ple

sios

aurs

the

supr

aocc

ipita

lte

nds

to b

ecom

e de

eper

, and

the

sutu

re w

ith th

eex

occi

pita

l and

pro

otic

bec

omes

long

er, m

ore

late

ral,

and

sigm

oid

in s

hape

. The

spa

ce fo

r th

e ve

rtic

alse

mic

ircul

ar c

anal

is u

sual

ly la

rger

and

dee

per

in th

ese

cond

type

of s

upra

occi

pita

l. F

ig. 6

.

60P

alat

eA

nter

ior

inte

rpte

rygo

idA

bsen

t (0)

, slit

-like

(1)

, bro

ad w

ith r

ound

The

pre

senc

e of

an

ante

rior

inte

rpte

rygo

id v

acui

ty is

ava

cuity

ends

(2)

reve

rsal

with

res

pect

to m

ore

basa

l sau

ropt

eryg

ians

,w

hich

hav

e a

clos

ed p

alat

e. F

igs.

4, 5

, etc

.

61P

alat

eP

oste

rior

inte

rpte

rygo

idA

bsen

t (0)

, pre

sent

(1)

Sto

rrs

1991

, cha

r. 1

1;T

he p

rese

nce

of a

n po

ster

ior

inte

rpte

rygo

id v

acui

ty is

vacu

ityS

ues

1987

a re

vers

al w

ith r

espe

ct to

mor

e ba

sal s

auro

pter

ygia

ns,

whi

ch h

ave

a cl

osed

pal

ate.

Pre

sent

in a

ll pl

esio

saur

san

d P

isto

saur

us. F

igs.

6, 7

, 8, e

tc.


Pal

ate

Pte

rygo

ids

mee

tP

tery

goid

s do

not

mee

t (0)

, pte

rygo

ids

Will

isto

n 19

08 il

lust

rate

sIn

Pis

tosa

urus

and

som

e Lo

wer

Jur

assi

c pl

esio

saur

spo

ster

ior

to p

oste

rior

mee

t (1)

, mee

t but

are

cov

ered

by

stat

e tw

oth

e pt

eryg

oids

do

not m

eet o

n th

e m

idlin

e of

the

pala

tein

terp

tery

goid

vac

uity

post

erio

r pa

rasp

heno

id p

roce

ss (

2)su

rfac

e be

hind

the

post

erio

r in

terp

tery

goid

vac

uity

.M

ost l

ater

ple

sios

aurs

hav

e di

stin

ct p

tery

goid

proc

esse

s w

hich

mee

t on

the

mid

l ine

behi

nd th

eva

cuity

. Thi

s ch

arac

ter

is o

rder

ed b

ecau

se s

tate

two

isde

pend

ent o

n th

e po

sses

sion

of s

tate

one

. Fig

s. 6

,11

and

17.

63P

alat

eP

tery

goid

s m

eet

Do

not m

eet b

etw

een

vacu

ities

(0)

, do

In p

lesi

osau

rs p

osse

ssin

g bo

th a

nter

ior

and

post

erio

rbe

twee

n an

terio

r an

dm

eet b

etw

een

vacu

ities

(1)

inte

rpte

rygo

id v

acui

ties,

the

pter

ygoi

ds m

ay o

r m

aypo

ster

ior

inte

rpte

rygo

idno

t mee

t bet

wee

n th

e tw

o va

cuiti

es. I

n ta

xa in

whi

chva

cuiti

esth

e pt

eryg

oids

do

not m

eet,

the

two

vacu

ities

are

sepa

rate

d by

the

cultr

iform

pro

cess

of t

hepa

rasp

heno

id. F

igs.

4, 6

, 7, e

tc.

64P

alat

eB

asio

ccip

ital e

xpos

edE

xpos

ed (

0), n

ot e

xpos

ed (

1)T

his

char

acte

r is

con

ditio

nal o

n th

e pr

esen

ce o

f apo

ster

ior

to p

oste

rior

deriv

ed s

tate

for

char

acte

r 62

. The

med

ial p

roce

sses

pter

ygoi

d su

ture

of th

e pt

eryg

oid

form

ing

the

med

ial s

ymph

ysis

beh

ind

the

post

erio

r in

terp

tery

goid

vac

uity

eith

er c

ompl

etel

yco

ver

the

body

of t

he b

asio

ccip

ital,

or fa

il to

cov

er it

.F

igs.

7 a

nd 8

.

65P

alat

eE

ctop

tery

goid

rea

ches

Doe

s no

t (0)

, doe

s (1

)In

Pel

oneu

stes

, the

ect

opte

rygo

id e

xten

ds m

edia

lly to

med

ially

to la

tera

lne

ar th

e la

tera

l mar

gin

of th

e po

ster

ior

inte

rpte

rygo

idm

argi

n of

pos

terio

rva

cuity

, ove

rlapp

ing

the

pter

ygoi

d. F

ig. 1

1.in

terp

tery

goid

vac

uitie

s

66P

alat

eC

olum

nar

ecto

pter

ygoi

dN

o co

ntac

t (0)

, con

tact

(1)

Illus

trat

ed b

y C

arpe

nter

,T

he e

ctop

tery

goid

in m

any

ples

iosa

uroi

d ta

xa r

ises

cont

acts

pos

torb

ital b

ar19

97do

rsal

ly o

ut o

f the

pla

ne o

f the

pal

ate,

and

con

tact

sth

e ve

ntro

-med

ial m

argi

n of

the

post

orbi

tal b

ar. T

his

char

acte

r is

sha

red

by e

lasm

osau

rs, c

rypt

oclid

ids,

and

poly

coty

lids.

Fig

s. 1

6 an

d 17

.

67pa

late

Dis

hed

pter

ygoi

dsA

bsen

t (0)

, pre

sent

(1)

In p

olyc

otyl

ids,

the

pter

ygoi

ds a

nter

o-la

tera

l and

late

ral t

o th

e po

ster

ior

inte

rpte

rygo

id v

acui

ties

are

broa

dly

dish

ed o

r de

pres

sed

shal

low

ly a

long

thei

rle

ngth

. Thi

s ch

arac

ter

was

obs

erve

d in

Dol

icho

rhyn

chop

s, T

rinac

rom

erum

, and

MO

R 7

51,

and

is n

ot a

pre

serv

atio

nal a

rtifa

ct. F

ig. 1

7.

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—68

Pal

ate

Pos

terio

r pt

eryg

oid/

Abs

ent (

0), p

rese

nt (

1)Il l

ustr

ated

by

And

rew

s,In

Tric

leid

us a

nd th

e po

lyco

tyl id

s, th

e pt

eryg

oids

sen

dpa

rasp

heno

id c

onta

ct19

10ou

t dis

tinct

med

ial p

roce

sses

that

con

tact

the

post

erio

rm

argi

n of

the

para

sphe

noid

. The

se p

roce

sses

mee

t in

a m

edia

n su

ture

in th

e po

lyco

tyl id

s, b

ut I

do n

otbe

lieve

this

con

ditio

n is

hom

olog

ous

to th

e co

nditi

on in

char

acte

r 62

. Fig

s. 1

6 an

d 17

.

69P

alat

eE

ctop

tery

goid

and

Do

not f

orm

flan

ges

(0),

form

flan

ges

(1),

Sta

te tw

o fig

ured

by

The

form

atio

n of

acc

esso

ry fl

ange

s ar

ound

the

pter

ygoi

d fo

rm la

tera

lfla

nges

mee

t in

shor

t, di

shed

con

tact

at

Whi

te 1

935

post

erio

r in

tern

pte

rygo

id v

acui

ty is

cha

ract

eris

tic o

ffla

nges

ven

tro-

late

ral

mid

l ine

(2),

mee

t in

broa

d co

ntac

t (3)

alm

ost a

l l pl

iosa

urs

excl

usiv

e of

the

rhom

aleo

saur

ids.

to p

oste

rior

pter

ygoi

dS

tate

one

occ

urs

in A

ttenb

oros

auru

s. S

tate

two

occu

rsva

cuity

in P

elon

eust

es a

nd K

rono

saur

us; s

tate

thre

e oc

curs

inLi

ople

urod

on, P

liosa

urus

, and

Bra

chau

chen

ius.

Fig

s. 1

1 an

d 13

.

70B

rain

case

Par

asph

enoi

dLo

ng, t

aper

ing

ante

riorly

(0)

, sho

rt a

ndA

ndre

ws

1910

p. 8

1–89

;T

he a

nter

ior

port

ion

of th

e pa

rasp

heno

id r

uns

mor

phol

ogy

blun

t(1)

Will

isto

n 19

03 p

.218

ante

riorly

in a

long

, tap

erin

g cu

ltrifo

rm p

roce

ss in

Ara

eosc

elis

, oth

er p

rimiti

ve d

iaps

ids,

and

Ple

sios

auru

s . In

the

cryp

tocl

idid

s an

d po

lyco

tylid

s, th

ean

terio

r po

rtio

n of

the

para

sphe

noid

term

inat

es in

ash

ort,

blun

t pro

cess

with

pro

min

ent l

ater

alar

ticul

atio

ns fo

r th

e pt

eryg

oids

loca

ted

at e

ither

sid

eon

the

pala

te s

urfa

ce. F

igs.

6, 1

6, a

nd 1

7.

71P

alat

eP

aras

phen

oid

keel

Not

kee

led

(0),

sha

rp k

eel (

1), k

eele

dT

he v

entr

al s

urfa

ce o

f the

par

asph

enoi

d, v

isib

lean

terio

rly (

2)th

roug

h th

e po

ster

ior

inte

rpte

rygo

id v

acui

ties,

has

ash

arp

keel

in v

ario

us ta

xa. C

arpe

nter

(19

97)

illus

trat

esst

ate

one

in L

ibon

ecte

s. P

elon

eust

es a

nd o

ther

plio

saur

s po

sses

s st

ate

two.

Fig

s. 7

and

11.

72P

alat

eP

aras

phen

oid

Ant

erio

r pa

rasp

heno

id n

ot e

xpos

ed o

nT

he a

nter

ior

port

ion

of th

e pa

rasp

heno

id is

eith

erex

posu

re a

nter

ior

topa

late

sur

face

(0)

, exp

osed

via

ext

ensi

onex

pose

d on

the

pala

te s

urfa

ce o

r co

vere

d by

the

post

erio

r in

terp

tery

goid

of p

oste

rior

inte

rpte

rygo

id v

acui

ties

(1)

pter

ygoi

ds. S

tate

one

ref

ers

to e

xpos

ure

of th

eva

cuiti

esex

pose

d w

ith la

tera

l pte

rygo

id s

utur

es (

2)pa

rasp

heno

id b

elow

the

pala

te s

urfa

ce d

ue to

enla

rgem

ent o

f the

pos

terio

r in

terp

tery

goid

vac

uitie

s;st

ate

two

refe

rs to

exp

osur

e on

the

pala

te s

urfa

ce,

acco

mpa

nied

by

late

ral s

utur

es w

ith th

e pt

eryg

oids

.F

igs.

6, 7

, 11,

and

13.


Pal

ate

Pos

sess

ion

of c

rista

eP

rese

nt (

0), a

bsen

t (1)

Vau

ghn

1955

, Rei

szA

s de

scrib

ed a

bove

, the

ple

sios

aur

brai

ncas

e is

vent

rola

tera

les

1981

prim

itive

in th

e re

tent

ion

of c

rista

e ve

ntro

late

rale

s of

the

para

sphe

noid

, at l

east

in L

ower

Jur

assi

c ta

xa. T

heco

nfigu

ratio

n in

ear

ly p

lesi

osau

rs d

iffer

s fr

om e

arl ie

rdi

apsi

ds in

that

the

basi

sphe

noid

foss

a is

rep

lace

d by

a di

sc o

f end

ocho

ndra

l bon

e (b

asis

phen

oid)

con

fluen

tw

ith th

e m

edia

l mar

gins

of t

he c

rista

e ve

ntro

late

rale

s.F

ig. 1

.

74B

rain

case

Par

asph

enoi

d/A

bsen

t (0)

, pre

sent

(1)

Giv

en th

e co

nfigu

ratio

n de

scrib

ed in

cha

ract

er 7

3, th

eba

sioc

cipi

tal c

onta

ctpa

rasp

heno

id is

sep

arat

ed fr

om th

e ba

sioc

cipi

tal o

non

mid

l ine.

the

mid

l ine

by th

e ba

sisp

heno

id in

ear

ly p

lesi

osau

rs.

In s

ome

cryp

tocl

idid

s an

d al

l pol

ycot

ylid

s, th

epa

rasp

heno

id e

xten

ds b

ackw

ard

over

this

are

a an

dco

ntac

ts th

e ve

ntro

-ant

erio

r m

argi

n of

the

basi

occi

pita

lon

the

mid

l ine.

Fig

s. 1

6 an

d 17

.

75P

alat

eP

osse

ssio

n of

bas

alP

rese

nt (

0), a

bsen

t (1)

Illus

trat

ed fo

r T

hala

ssio

drac

on in

Sto

rrs

and

Tay

lor

artic

ulat

ion

(199

4) a

nd p

rese

nt in

Ple

sios

auru

s , th

e ba

sal

artic

ulat

ion

is p

rese

nt a

nd p

rom

inen

t in

all

ples

iosa

uroi

ds. T

he a

rtic

ulat

ion

appe

ars

abse

nt in

mos

t plio

saur

s; h

owev

er, o

ne s

kull

of P

elon

eust

es(B

MN

H R

. 380

3) p

rese

rves

this

feat

ure.

The

basi

sphe

noid

and

the

basa

l art

icul

atio

n ar

isin

g fr

om it

are

very

poo

rly o

ssifi

ed in

mos

t plio

saur

ids;

the

Pel

oneu

stes

sku

ll m

entio

ned

here

is u

nusu

al in

the

pres

erva

tion

of a

n ex

trem

ely

delic

ate

and

poor

lyos

sifie

d ba

sisp

heno

id in

whi

ch th

e ar

ticul

atio

n is

visi

ble.

The

are

a of

art

icul

atio

n w

ith th

e do

rsal

sur

face

of th

e pa

late

is u

sual

ly v

isib

le, h

owev

er, i

n pl

iosa

urm

ater

ial i

n w

hich

the

skul

l roo

f has

bee

n re

mov

ed.

The

fact

that

the

char

acte

r is

pre

sent

in a

ll ta

xa m

akes

this

cha

ract

er u

ninf

orm

ativ

e; it

is in

clud

ed d

ue to

prev

ious

con

fusi

on a

bout

the

pres

ence

of t

he b

asal

artic

ulat

ion.

Fig

s. 6

, 16,

and

17.

76P

alat

eB

asio

ccip

ital t

uber

sN

ot r

educ

ed (

0), r

educ

ed/ t

uber

face

tsA

ndre

ws

(191

0) il

lust

rate

s th

e ba

sioc

cipi

tal i

nre

duce

dco

nflue

nt w

ith b

asis

phen

oid

Tric

leid

us; i

n th

is ta

xon

and

in th

e po

lyco

tylid

s, th

ear

ticul

atio

n (1

)ba

sioc

cipi

tal t

uber

s ar

e re

duce

d, a

nd th

eir

pter

ygoi

dar

ticul

ar fa

cets

are

con

fluen

t with

the

med

ian

basi

sphe

noid

art

icul

atio

n. F

ig. 1

6.

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—77

Pal

ate

Juga

l has

sm

all

No

expo

sure

(0)

, exp

osur

e (1

)In

Pel

oneu

stes

and

som

e ot

her

plio

saur

s, th

e ju

gal

expo

sure

on

pala

teha

s a

smal

l exp

osur

e on

the

pala

te s

urfa

ce b

etw

een

surf

ace

the

max

i l la

and

squa

mos

al.

78P

alat

eLa

tera

l pal

atal

Abs

ent (

0), p

rese

nt (

1)S

ome

plio

saur

s ha

ve s

mal

l fen

estr

a in

the

pala

te,

fene

stra

tion

bord

ered

form

ed b

y th

e la

ck o

f a s

utur

e be

twee

n th

e pt

eryg

oid

by p

alat

ine

and

and

pala

tine

near

the

post

erio

r m

argi

n of

the

pala

tine.

pter

ygoi

dF

igs.

7 a

nd 8

.

79P

alat

eP

alat

ine/

inte

rnal

nar

isP

alat

ine

ente

rs in

tern

al n

aris

bor

der

(0),

The

pal

atin

e is

exc

lude

d fr

om th

e in

tern

al n

aris

by

aex

clud

ed b

y vo

mer

/max

i l la

cont

act (

1)su

ture

bet

wee

n th

e vo

mer

and

max

i l la

in L

iopl

euro

don

and

Plio

saur

us.

80P

alat

eP

alat

ines

app

roac

hD

o no

t mee

t (0)

, clo

se a

ppro

ach

or m

eet

Will

isto

n 19

03, 1

910

Fig

. 13.

clos

ely

or m

eet a

tat

mid

line

(1)

mid

line

81P

alat

eP

rem

axill

a/ a

nter

ior

Pre

max

illa

ente

rs a

nter

ior

bord

er (

0), i

sR

iepp

el 1

994a

, 199

7b,

bord

er o

f int

erna

l nar

isex

clud

ed b

y vo

mer

/ max

illa

cont

act (

1)ch

ars.

35,

45

82P

alat

eS

ub-o

rbita

l fen

estr

atio

nA

bsen

t (0)

, pre

sent

(1)

Sto

rrs

1991

, cha

r. 9

Sub

-orb

ital f

enes

tra

are

pres

ent i

n m

any

plio

saur

s.F

igs.

8 a

nd 1

3.

83P

alat

eV

omer

s ex

tend

far

Do

not (

0), e

xten

d po

ster

ior

and

mee

tF

igs.

9, 2

, 11,

etc

.po

ster

ior

to in

tern

alpt

eryg

oids

in w

ide

inte

rdig

itatin

g su

ture

(1)

nare

s on

mid

line

84P

alat

eP

rom

inen

t ‘pt

eryg

oid

Abs

ent (

0), p

rese

nt (

1)R

iepp

el 1

994a

, 199

7b,

As

disc

usse

d by

Sto

rrs

(199

7), t

he ‘p

tery

goid

flan

ge’

flang

e’/ e

ctop

tery

goid

char

s. 3

5, 4

4; S

torr

spr

esen

t in

som

e pl

iosa

urs

is n

ot a

true

pte

rygo

idbo

ss19

97fla

nge,

bec

ause

it is

com

pris

ed a

lmos

t ent

irely

by

the

ecto

pter

ygoi

d. S

torr

s th

eref

ore

sugg

ests

the

term

‘ect

opte

rygo

id b

oss’

for

this

feat

ure.

Fig

s. 1

1 an

d 13

.

85P

alat

eE

ctop

tery

goid

bos

sC

onta

ct a

bsen

t (0)

, con

tact

s ju

gal (

1)T

he e

ctop

tery

goid

bos

s ca

n ei

ther

be

free

of t

heha

s w

ide

cont

act w

ithm

edia

l wal

l of t

he s

kull

roof

, or

cont

act t

he ju

gal a

ndju

gal/

squa

mos

alor

squ

amos

al. F

ig. 1

6.

86M

andi

ble

Bow

edm

axill

aA

bsen

t(0)

pres

ent(

1)T

his

char

acte

rre

fers

tom

andi

bles

that

expa

nd


86M

andi

ble

Bow

ed m

axill

aA

bsen

t (0)

, pre

sent

(1)

Thi

s ch

arac

ter

refe

rs to

man

dibl

es th

at e

xpan

dno

ticea

bly

ante

rior

of th

e ja

w a

rtic

ulat

ions

; suc

hm

andi

bles

hav

e a

hoop

-like

or

bow

ed a

ppea

ranc

ew

hen

view

ed o

n th

e ve

ntra

l sur

face

. Fig

. 7.

87M

andi

ble

Mec

kel ia

n ca

nal o

pen

Not

ope

n (0

) op

en (

1)T

he l i

ngua

l sur

face

of t

he lo

wer

jaw

is p

oorly

oss

ified

ante

riorly

in p

lesi

osau

rs; h

owev

er, i

n so

me

taxa

the

sple

nial

does

not

oss

ify a

t al l,

leav

ing

the

Mec

kel ia

n ca

nal

open

far

ante

rior

to th

e ja

w a

rtic

ulat

ion.

88M

andi

ble

Ven

tral

man

dibu

lar

No

ridge

(0)

, rid

ge (

1)T

he r

hom

aleo

saur

id ja

w s

ymph

ysis

has

a d

istin

ctrid

ge/ p

edes

tal-l

ike

ridge

or

pede

stal

-l ike

ela

bora

tion

alon

g its

ven

tral

sym

phys

ism

argi

n. T

his

ridge

ext

ends

pos

terio

rly fo

r a

shor

tdi

stan

ce p

ast t

he s

ymph

ysis

alo

ng e

ach

jaw

ram

us.

Fig

. 7.

89M

andi

ble

Man

dibu

lar

sym

phys

isS

hort

(0)

, som

ewha

t enf

orce

d (1

),M

odifi

ed fr

om R

iepp

elT

he le

ngth

of t

he m

andi

bula

r sy

mph

ysis

has

bee

nsc

oopl

ike

(2),

long

(3)

1997

b, c

har.

51;

Bro

wn

hist

oric

ally

impo

rtan

t in

clas

sify

ing

the

plio

saur

s (T

arlo

1981

, cha

r. 5

; Tar

lo19

60).

My

stat

e ‘s

coop

like’

app

lies

to b

oth

the

1960

rhom

aleo

saur

id a

nd L

iopl

euro

don

cond

ition

s; ‘l

ong’

appl

ies

to th

e co

nditi

on in

Pel

oneu

stes

. Fig

s. 7

and

13.

90M

andi

ble

Spl

enia

l par

ticip

ates

inD

oes

not p

artic

ipat

e (0

), d

oes

part

icip

ate

The

spl

enia

l ent

ers

the

man

dibu

lar

sym

phys

is in

all

sym

phys

is(1

), a

ngul

ars

exte

nd p

ast s

ymph

ysis

(2)

long

-sno

uted

taxa

. Sta

te tw

o de

scrib

es th

epo

lyco

tylid

s, in

whi

ch th

e sy

mph

ysis

is s

o lo

ng th

at it

exte

nds

post

erio

r to

the

ante

rior

mar

gin

of th

ean

gula

rs. T

his

char

acte

r is

ord

ered

. Fig

s. 9

and

12.

91M

andi

ble

Ling

ual m

andi

bula

rA

bsen

t (0)

, pre

sent

(1)

Tha

umat

osau

rus

poss

ess

a fe

nest

ra in

this

pos

ition

,fe

nest

rabo

unde

d by

the

sple

nial

, ang

ular

, and

pre

artic

ular

.F

ig. 7

.

92M

andi

ble

Mor

phol

ogy

of d

enta

ry/

Ang

ular

pro

ject

s fo

rwar

d of

sur

angu

lar

inIn

mos

t ple

sios

aurs

, the

sut

ure

of th

e de

ntar

y w

ith th

ean

gula

r- s

uran

gula

rla

tera

l vie

w (

0), s

uran

gula

r an

terio

ran

gula

r an

d su

rang

ular

on

the

late

ral s

urfa

ce o

f the

sutu

repr

oces

s (1

)m

andi

ble

is r

elat

ivel

y st

raig

ht (

Sto

rrs

& T

aylo

r 19

96);

how

ever

in p

liosa

urno

ids

the

sura

ngul

ar s

ends

a p

roce

ssan

terio

rly in

to a

n em

baym

ent i

n th

e de

ntar

y. F

ig. 1

2.

93M

andi

ble

Cor

onoi

dP

rese

nt (

0), a

bsen

t (1)

Cru

icks

hank

199

4b,

The

sta

tus

of th

e co

rono

id a

nd p

rear

ticul

ar is

a lo

ng-

char

. 9st

andi

ng p

robl

em in

ple

sios

aurs

. I b

elie

ve th

e co

rono

idto

be

pres

ent i

n al

l tax

a ex

cept

Kim

mer

osau

rus ,

cont

ra C

ruic

ksha

nk (

1994

b). F

igs.

12,

15,

and

19.

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—94

Low

er J

awLo

ng l i

ngua

l cor

onoi

dA

bsen

t (0)

, pre

sent

(1)

The

cor

onoi

d in

pl io

saur

s ru

ns a

nter

iorly

to th

epr

oces

sm

andi

bula

r sy

mph

ysis

. Fig

. 12.

95M

andi

ble

Cor

onoi

d ex

pose

d on

No

expo

sure

(0)

, exp

osur

e (1

)F

ig. 2

4. In

term

edia

te s

tate

in M

urae

nosa

urus

late

ral j

aw s

urfa

cei l l

ustr

ated

by

And

rew

s (1

910)

is c

orre

ct, a

lthou

gh h

eid

entifi

es th

is b

one

as th

e sp

leni

al r

athe

r th

an th

eco

rono

id F

ig 1

9.

96M

andi

ble

Pre

artic

ular

Pre

sent

(0)

, abs

ent (

1)C

ruic

ksha

nk 1

994b

,C

ruic

ksha

nk (

1994

b) b

elie

ved

the

prea

rtic

ular

to b

ech

ar. 9

pres

ent b

ut s

mal

l in

ples

iosa

urs;

I w

as a

ble

to c

onfir

mits

pre

senc

e in

al l

taxa

with

ade

quat

e pr

eser

vatio

n.F

igs.

12

and

19.

97M

andi

ble

Pre

artic

ular

she

lf/A

bsen

t (0)

, pre

sent

(1)

And

rew

s 19

10In

cry

ptoc

lidid

s an

d po

lyco

tylid

s, th

e pr

eart

icul

ar fo

rms

groo

vea

shel

f bel

ow th

e po

ster

ior

end

of th

e M

ecke

lian

cana

l,w

hich

is a

dis

tinct

gro

ove.

The

pre

artic

ular

fits

into

aso

cket

in th

e an

gula

r. N

oted

in M

urae

nosa

urus

by

And

rew

s (1

910)

. Fig

. 19.

98M

andi

ble

Jaw

art

icul

atio

n in

Abo

ve o

r at

col

linea

r w

ith to

oth

row

(0)

,F

igs.

12,

14,

and

15.

rela

tion

to to

oth

row

low

er th

an to

oth

row

(1)

99S

kull

shap

eD

iast

ema

at m

axill

a/A

bsen

t (0)

, pre

sent

(1)

Mod

ified

from

Sto

rrs

Fig

s. 2

and

11.

prem

axill

a su

ture

1991

, cha

r. 3

7

100

Den

titio

nF

irst t

ooth

afte

rLa

rge

(0),

red

uced

(1)

The

firs

t max

illar

y to

oth

is g

ener

ally

muc

h sm

alle

r th

andi

aste

ma

thos

e ca

udal

to it

in ta

xa p

osse

ssin

g a

dias

tem

a.F

igs.

2 a

nd 1

1.

101

Den

titio

nP

rem

axill

a an

d de

ntar

yA

bsen

t (0)

, pre

sent

(1)

Rie

ppel

199

4a, 1

997b

,F

ig. 7

.fa

ngs

char

s. 4

4, 5

5; S

torr

s 19

91,

char

. 39;

Bro

wn

1981

,ch

ar. 8

102

Den

titio

nO

ne o

r tw

o ca

nini

form

Pre

sent

(1)

, abs

ent (

0)R

iepp

el 1

994a

, 199

7b,

teet

h on

max

illa

char

s. 4

5, 5

6; S

torr

s 19

91,

char

. 41

103

Den

titio

nT

ooth

form

Gra

cile

smal

lroo

tna

rrow

now

ear

(0)

Bro

wn

1981

char

3F

igs

45

11an

d14

Too

thty

pes

defin

edby

Mas

sare


103

Den

titio

nT

ooth

form

Gra

cile

, sm

all r

oot,

narr

ow, n

o w

ear

(0)

Bro

wn

1981

, cha

r. 3

,F

igs.

4, 5

, 11,

and

14.

Too

th ty

pes

defin

ed b

y M

assa

rero

bust

, lar

ge r

oot,

wea

r (1

), v

ery

smal

l/T

arlo

196

0(1

987)

wer

e no

t use

d be

caus

e m

ost p

lesi

osau

rs h

ave

need

le-li

ke (

2)th

e sa

me

type

of t

eeth

in th

is m

ore

gene

ral c

odin

g.

104

Too

th s

hape

Tee

th r

ound

or

with

Rou

nd (

0), p

lana

r fa

ce (

1)T

arlo

196

0re

info

rced

pla

nar

face

105

Too

th o

rnam

ent

Long

itudi

nal s

tria

tions

Str

iatio

ns a

l l ar

ound

(0)

, lin

gual

onl

y (1

),T

arlo

196

0on

teet

hno

ne (

2)

106

Den

titio

nN

umbe

r of

pre

max

i l lar

y5(

0), 6

(1),

7(2

), g

reat

er th

an 7

(3)

Bro

wn

1981

, cha

r. 7

;T

his

char

acte

r is

ord

ered

. Fig

s. 2

and

11.

teet

hC

ruic

ksha

nk 1

994b

,ch

ar. 1

107

Den

titio

nM

axi l l

ary

teet

hLe

ss th

an tw

enty

(0)

, mor

e tw

enty

toC

ruic

ksha

nk 1

994b

,T

his

char

acte

r is

ord

ered

.th

irty

(1),

man

y m

ore

than

thirt

y (2

)ch

ar. 1

108

Atla

s/ A

xis

Num

ber

of a

xis

rib2(

0), 1

(1)

Thi

s ch

arac

ter

is d

ifficu

lt to

sco

re in

man

y ta

xa d

ue to

head

spo

or p

rese

rvat

ion

and/

or in

com

plet

e os

sific

atio

n.

109

Atla

s/ A

xis

Art

icul

atio

n of

axi

s rib

Bro

ad a

rtic

ulat

ion

with

atla

s ce

ntru

mA

ndre

ws

1910

, 191

3T

his

char

acte

r is

var

iabl

e w

ithin

Pel

oneu

stes

, and

may

and/

or o

ther

ele

men

ts (

0), h

ead

confi

ned

be o

ntog

enet

ical

ly v

aria

ble.

Diffi

cult

to s

core

in a

dult

to a

xis

cent

rum

(1)

indi

vidu

als

in w

hich

the

atla

s/ax

is c

ompl

ex is

gen

eral

ly fu

sed.

110

Atla

s/ A

xis

Atla

s/ax

is m

orph

olog

yN

o la

tera

l exp

osur

e of

atla

s ce

ntru

m o

n cu

pA

ndre

ws

1909

, Will

isto

nfa

ce (

0), l

ater

al e

xpos

ure

(1),

no

late

ral

1910

, Bro

wn

1981

, cha

r.ex

posu

re, b

ut a

tlas

and

axis

inte

rcen

tra

13. A

lso

Rom

er, 1

956

excl

ude

atla

s ce

ntru

m v

entr

ally

(2)

111

Ver

tebr

aeN

umbe

r of

cer

vica

lP

rimiti

ve (

0), i

ncre

ased

(1)

, red

uced

(2)

,B

row

n 19

81, c

har.

14

The

num

ber

of c

ervi

cal v

erte

brae

is u

nfor

tuna

tely

vert

ebra

egr

eate

r th

an 5

0un

know

n in

Pis

tosa

urus

(S

ues

1987

); h

owev

er th

is ta

xon

is s

imila

r to

ples

iosa

urs

in p

osse

ssin

g ‘p

ecto

ral’

verte

brae

,de

fined

as

vert

ebra

e in

whi

ch th

e rib

art

icul

atio

n ar

ises

from

a s

hort

tran

sver

se p

roce

ss a

risin

g fr

om b

oth

the

cent

rum

and

neu

ral a

rch

(illu

stra

ted

in B

row

n, 1

981)

.H

ere

I defi

ne c

ervi

cal v

erte

brae

as

vert

ebra

e in

whi

chth

e rib

art

icul

atio

n ar

ises

from

the

cent

rum

onl

y. B

row

n(1

981)

als

o be

lieve

d 28

–32

cerv

ical

s to

be

prim

itive

inpl

esio

saur

s; I

have

ret

aine

d th

is c

riter

ion.

Sta

te o

ne is

33 c

ervi

cals

or

larg

er, w

hile

sta

te tw

o is

few

er th

an 2

8.S

tate

thre

e co

ncer

ns n

ecks

of 5

0 ce

rvic

als

or lo

nger

.T

his

char

acte

r is

ord

ered

usi

ng th

e ch

arac

ter

stat

e tr

ee((

2)1,

3)0.

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—11

2M

orph

o-m

etric

Pro

port

ions

of c

ervi

cal

Leng

th e

qual

to h

eigh

t (0)

, len

gth

grea

ter

Bro

wn

1981

, cha

r. 1

5;W

elle

s (1

952)

iden

tified

ont

ogen

etic

var

iatio

n in

this

cent

rath

an h

eigh

t (1)

, len

gth

less

than

Wel

les

1952

char

acte

r, a

s w

ell a

s va

riatio

n al

ong

the

vert

ebra

lhe

ight

(2)

colu

mn,

but

als

o fo

und

that

taxo

nom

ical

ly r

elev

ant

inte

rspe

cific

diff

eren

ces

exis

ted.

I sc

ored

this

char

acte

r lo

osel

y; v

erte

brae

had

to b

e m

arke

dly

com

pres

sed

or e

long

ated

ove

r m

ost o

f the

col

umn

tobe

sco

red

as d

eriv

ed.

113

Ver

tebr

aeD

istin

ct c

hang

e in

No

chan

ge in

ang

le (

0), c

hang

e (1

)N

oted

by

Wel

les

1962

In e

lasm

osau

rs a

nd s

ome

othe

r ta

xa, t

he c

ervi

cal

zygo

poph

ysea

l ang

lezy

gopo

phys

es a

re o

rient

ed d

orso

-ven

tral

ly in

the

alon

g ce

rvic

al c

olum

nan

terio

r pa

rt o

f the

col

umn.

Thi

s or

ient

atio

n sh

ifts

grad

ually

to m

edio

-late

ral i

n th

e po

ster

ior

part

of t

hene

ck.

114

Ver

tebr

aeV

entr

al k

eel o

n ce

rvic

alA

bsen

t (0)

, pre

sent

(1)

Tar

lo 1

960

vert

ebra

e

115

Ver

tebr

aeLa

tera

l rid

ge o

nA

bsen

t (0)

, pre

sent

(1)

Bro

wn

1981

, cha

r. 1

6;A

low

, lat

eral

rid

ge is

pre

sent

on

the

cent

rum

bod

yan

terio

r ce

rvic

alill

ustr

ated

in W

elle

s,ab

ove

the

rib a

rtic

ulat

ion

in e

lasm

osau

rs a

nd s

ome

vert

ebra

e in

adu

lts19

43ot

her

ples

iosa

uroi

ds.

116

Ver

tebr

aeB

inoc

ular

sha

ped

Abs

ent (

0), p

rese

nt (

1)W

elle

s 19

43T

he a

nter

ior

cerv

ical

cen

tra

in s

ome

elas

mos

aurs

ante

rior

cerv

ical

cen

tra

have

a d

istin

ct d

orso

-ven

tral

con

stric

tion

med

ially

,yi

eldi

ng a

cen

trum

that

has

a ‘b

inoc

ular

’ out

line

inan

terio

r or

pos

terio

r vi

ew.

117

Ver

tebr

aeN

umbe

r of

cer

vica

l rib

Tw

o (0

), o

ne (

1)S

ande

r et

al .

1997

;he

ads

Bro

wn

1981

, cha

r. 2

1

118

Ver

tebr

aeV

entr

al fo

ram

ina

inA

bsen

t (0)

, pre

sent

(1)

San

der

et a

l. 19

97;

Ter

med

“fo

ram

ina

subc

entr

alia

” by

Sto

rrs

(199

1), t

hece

rvic

al v

erte

brae

Sto

rrs

1991

, cha

r. 4

7po

sses

sion

of p

aire

d fo

ram

ina

in th

e ve

ntra

l sur

face

of

the

cerv

ical

cen

tra

is a

trai

t sha

red

by p

isto

saur

ids

and

all p

lesi

osau

rs.

119

Ver

tebr

aeF

oram

ina

subc

entr

alia

Med

ial a

nd la

rge

(0),

late

ral a

ndT

arlo

196

0; s

ee a

lso

redu

ced

and

late

ral

redu

ced

(1)

Will

isto

n 19

07

120

Ver

tebr

aeW

idth

of c

ervi

cal

Wid

er th

an c

entr

um (

0), s

ubeq

ual w

ithS

ande

r et

al.

1997

;T

his

char

acte

r is

ord

ered

.zy

gopo

phys

esce

ntru

m (

1), m

ore

narr

ow th

anS

torr

s 19

91 c

har.

48

cent

rum

(2)


cent

rum

(2)

121

Ver

tebr

aeP

oste

rior

artic

ulat

ion

Abs

ent (

0), p

rese

nt (

1)N

oted

in P

isto

saur

us b

y (S

ues

1987

) an

d in

for

succ

eedi

ng n

eura

lC

alla

way

asau

rus

(Wel

les

1962

), th

is fe

atur

e is

a s

mal

lsp

ine,

cer

vica

lno

tch

in th

e po

ster

ior

base

of t

he c

ervi

cal n

eura

l spi

neve

rteb

rae

whi

ch a

ccep

ts th

e an

terio

r ed

ge o

f the

suc

ceed

ing

neur

al s

pine

. Thi

s no

tch

may

rep

rese

nt th

e zy

gant

rum

pres

ent i

n m

ore

basa

l sau

ropt

eryg

ians

; how

ever

, no

corr

espo

ndin

g zy

gosp

hene

is e

ver

pres

ent.

Lost

inm

any

plio

saur

s.

122

Ver

tebr

aeC

ervi

cal r

ib a

rtic

ulat

ion

Circ

ular

or

subc

ircul

ar (

0), e

long

ate

(1)

Il lus

trat

ed in

Wel

les

Ant

ero-

post

erio

r el

onga

tion

of th

e ce

rvic

al r

ibs,

and

grea

tly e

long

ate/

1943

elon

gatio

n of

thei

r ar

ticul

atio

n w

ith th

e ce

ntru

m, i

sce

rvic

al r

ibs

expa

nded

com

mon

in lo

ng-n

ecke

d ta

xa in

whi

ch th

e ce

ntru

m is

and

blad

e-l ik

elo

nger

than

wid

e.

123

Ver

tebr

aeA

nter

ior

proc

ess

ofP

rese

nt (

0), a

bsen

t (1)

Il lus

trat

ed in

San

der

A d

istin

ct a

nter

ior

proc

ess

is p

rese

nt o

n th

e ce

rvic

alce

rvic

al r

ibs

et a

l. 19

97, S

torr

s 19

97rib

s of

Aug

usta

saur

us, a

s w

ell a

s T

hala

ssio

drac

on,

Ple

sios

auru

s , a

nd s

ome

othe

r Ju

rass

ic p

lesi

osau

rs.

Thi

s pr

oces

s is

lost

in la

ter

ples

iosa

urs.

124

Ver

tebr

aeA

nter

ior

neur

al fl

ange

Abs

ent (

0), p

rese

nt (

1)M

urae

nosa

urus

and

som

e ot

her

ples

iosa

uroi

ds h

ave

aon

cer

vica

l neu

ral

dist

inct

flan

ge o

n th

e an

terio

r m

argi

n of

the

cerv

ical

spin

esne

ural

spi

nes.

Thi

s ch

arac

ter

is n

ot n

eces

sary

to fo

rmth

e ar

ticul

atio

n de

scrib

ed in

cha

ract

er 1

21.

125

Ver

tebr

aeN

eura

l spi

nes,

Ang

led

back

war

d (0

), n

ot a

ngle

d (1

)B

row

n 19

81, c

har.

20

The

cer

vica

l neu

ral s

pine

s in

ela

smos

aurs

and

som

ece

rvic

al v

erte

brae

othe

r ta

xa a

re n

ot a

ngle

d, w

hile

they

are

ang

led

back

war

d in

Tha

lass

iodr

acon

and

the

plio

saur

oids

.

126

Ver

tebr

aeD

ista

l end

of

No

diam

eter

incr

ease

(0)

, thi

cken

ed (

1)R

iepp

el 1

997b

, cha

r. 6

8T

hick

ened

tran

sver

se p

roce

sses

are

pre

sent

in a

lltr

ansv

erse

pro

cess

es,

ples

iosa

urs,

Pis

tosa

urus

, and

Aug

usta

saur

us.

dors

al v

erte

brae

127

Ver

tebr

aeD

orsa

l neu

ral a

rch

Sub

equa

l to

cent

rum

hei

ght (

0), s

hort

erS

ande

r et

al .

1997

The

neu

ral a

rch

tend

s to

be

smal

l and

sho

rt c

ompa

red

heig

htth

an c

entr

um h

eigh

t (1)

to th

e ce

ntru

m in

ple

sios

aurs

, whi

le it

is la

rger

in m

ore

basa

l sau

ropt

eryg

ians

.

128

Ver

tebr

aeZ

ygos

phen

e/P

rese

nt (

0), a

bsen

t (1)

San

der

et a

l . 19

97;

The

pis

tosa

urid

con

ditio

n is

als

o di

scus

sed

in S

ues

zyga

ntru

m a

rtic

ulat

ion

Rie

ppel

199

4a, 1

997b

,(1

987)

.ch

ars.

53,

67;

Sto

rrs

1991

, cha

r. 4

9

Con

tinue

d


pp

end

ix 1

. Con

tinue

d.—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—C

har.

type

Cha

ract

erS

tate

s/C

odin

gC

itatio

nR

emar

ks—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—12

9V

erte

brae

Hei

ght o

f neu

ral

Low

(0)

, low

and

rug

ose

(1),

hig

h (2

)S

ande

r et

al.

1997

The

dor

sal n

eura

l spi

nes

of A

ugus

tasa

urus

are

low

spin

es, d

orsa

lw

ith r

ugos

e to

ps; t

he s

pine

s in

Tha

lass

iodr

acon

are

vert

ebra

elo

w b

ut n

ot r

ugos

e; th

ose

in P

isto

saur

us a

re h

igh.

The

dors

al n

eura

l spi

nes

are

high

in a

l l pl

esio

saur

s.

130

Ver

tebr

aeLa

tera

l com

pres

sion

Not

com

pres

sed

(0),

com

pres

sed

and

San

der

et a

l. 19

97T

he n

eura

l spi

nes

in m

any

ples

iosa

urs

are

late

ral ly

of n

eura

l spi

nes,

blad

e-l ik

e (1

)co

mpr

esse

d an

d bl

ade-

l ike;

the

neur

al s

pine

s of

man

ydo

rsal

and

cer

vica

lpl

iosa

urs

lack

this

feat

ure.

vert

ebra

e

131

Pec

tora

l Gird

leIn

terc

lavi

cle

post

erio

rP

rese

nt (

0), a

bsen

t (1)

Sto

rrs

1991

, cha

r. 5

8T

he in

terc

lavi

cle

was

pro

babl

y pr

esen

t but

is n

otpr

oces

skn

own

in m

any

ples

iosa

urs.

132

Pec

tora

l Gird

leD

orsa

l pro

cess

of

Tap

ers

to b

lunt

tip

(0),

ven

tral

lyR

iepp

el 1

997b

, cha

r. 8

5sc

apul

aex

pand

ed p

oste

riorly

(1)

133

Pec

tora

l Gird

leP

rese

nce

of c

lavi

cles

Pre

sent

(0)

, int

ercl

avic

le a

bsen

t (1)

,M

odifi

ed fr

om B

row

nT

he in

terc

lavi

cle

and

clav

icle

s ar

e sl

ow to

oss

ify a

ndan

d in

terc

lavi

cle

both

abs

ent (

2)19

81, c

hars

. 22

and

23of

ten

do n

ot p

rese

rve

wel

l; P

lesi

osau

rus

is th

e on

lyta

xon

in w

hich

I co

uld

be s

ure

of th

e ab

senc

e of

the

inte

rcla

vicl

e, b

ased

on

Sto

rrs

1997

and

my

own

obse

rvat

ions

.

134

Pec

tora

l Gird

leC

lavi

cle

med

ian

Sym

phys

is (

0), s

epar

ated

by

inte

rcla

vicl

esy

mph

ysis

(1),

mee

t onl

y be

hind

not

ch (

2)

135

Pec

tora

l Gird

leS

capu

lae

mee

t in

Sep

arat

ed b

y cl

avic

les/

inte

rcla

vicl

e (0

),M

odifi

ed fr

om B

row

nT

he s

capu

lae

mee

t in

an a

nter

ior

med

ian

sym

phys

isan

terio

r m

edia

nm

eet m

edia

lly b

ut le

ave

notc

h fo

r de

rmal

1981

, cha

r. 2

4in

man

y la

ter

ples

iosa

urs;

how

ever

, the

ant

ero-

med

ial

sym

phys

isel

emen

ts (

1), m

eet i

n lo

ng s

ymph

ysis

proc

esse

s of

the

scap

ulae

are

usu

ally

sep

arat

ed b

yw

ith n

o no

tch

(2)

the

derm

al g

irdle

ele

men

ts in

plio

saur

s (c

ontr

a B

row

n19

81).

136

Pec

tora

l Gird

leA

nter

ior

intr

asca

pula

rA

bsen

t (0)

, pre

sent

(1)

Som

e cr

ypto

clid

ids

and

som

e po

lyco

tylid

s ha

ve a

fene

stra

smal

l fen

estr

a pe

rfor

atin

g th

e an

terio

r gi

rdle

ele

men

tson

the

mid

line.

137

Pec

tora

l Gird

leLo

ngitu

dina

l pec

tora

lA

bsen

t (0)

, for

med

by

clav

icle

and

Mod

ified

from

Sto

rrs

Thi

s ch

arac

ter

is c

erta

inly

var

iabl

e on

toge

netic

ally

, as

bar

cora

coid

(1)

, for

med

by

scap

ula

and

1991

, cha

r. 6

6; B

row

ndi

scus

sed

by B

row

n (1

981)

. I in

clud

e it

here

bec

ause

cora

coid

(2)

1981

, cha

r. 2

5m

ost o

f the

taxa

in th

is a

naly

sis

are

adul

ts, a

nd fo

r th

esa

ke o

f com

plet

enes

s.

138

Pec

tora

lGird

leS

prac

orac

oid

Pre

sent

(0)

abse

nt(1

)R

iepp

el19

97b

char

64T

hes

prac

orac

oid

fora

men

isab

sent

inpi

stos

arid

s


8P

ecto

ral G

irdle

Sup

raco

raco

idP

rese

nt (

0), a

bsen

t (1)

Rie

ppel

199

7b, c

har.

64;

The

sup

raco

raco

id fo

ram

en is

abs

ent i

n pi

stos

aurid

sfo

ram

en/ n

otch

Sto

rrs

1991

, cha

r. 6

4an

d al

l ple

sios

aurs

.

139

Pec

tora

l Gird

leC

orac

oid

shap

eR

ound

ed c

onto

urs/

not

pla

te-li

ke (

0),

Rie

ppel

199

7b, c

har.

88;

expa

nded

med

ian

sym

phys

is (

1)S

torr

s 19

91, c

har.

63

140

Pec

tora

l Gird

leM

edia

n co

raco

idA

bsen

t (0)

, pre

sent

(1)

Il lus

trat

ed in

Wil l

isto

nM

ost p

olyc

otyl

ids

have

one

or

two

perf

orat

ions

on

perf

orat

ions

1906

, 190

6ei

ther

sid

e of

the

mid

l ine

in th

e po

ster

ior

exte

nsio

ns o

fth

e co

raco

ids.

141

Pec

tora

l Gird

leP

oste

rior

cora

coid

Abs

ent (

0), p

rese

nt (

1)B

row

n 19

81, c

har.

27

Wel

les

(194

3, 1

962)

and

man

y ot

hers

hav

eex

tens

ion

with

dee

pdo

cum

ente

d th

at th

e po

ster

ior

exte

nsio

ns o

f the

med

ian

emba

ymen

tco

raco

ids

are

long

and

sur

roun

d a

deep

med

ian

emba

ymen

t in

man

y el

asm

osau

rs.

142

Pec

tora

l Gird

leP

oste

ro-la

tera

lA

bsen

t (0)

, pre

sent

(1)

Bro

wn

1981

, cha

r. 2

6S

torr

s (1

997)

and

Bro

wn

(198

1) d

iscu

ss th

e cl

ear

cora

coid

win

gson

toge

netic

var

iatio

n in

this

cha

ract

er. I

t is

incl

uded

here

bec

ause

mos

t gen

era

in th

is a

naly

sis

are

adul

ts,

and

for

the

sake

of c

ompl

eten

ess.

143

Pel

vic

Gird

leC

onta

ct b

etw

een

Pre

sent

(0)

, abs

ent (

1)S

torr

s 19

91, c

har.

68;

The

loss

of t

he p

rimiti

ve c

onta

ct b

etw

een

the

ilium

and

ilium

and

pub

isS

ues

1987

pubi

s ha

s lo

ng b

een

used

as

a di

agno

stic

cha

ract

er o

fth

e P

lesi

osau

ria (

i.e. R

omer

, 195

6, p

. 329

).

144

Pel

vic

Gird

leP

ubis

ven

tral

Con

vex

(1),

con

cave

(0)

Rie

ppel

199

7b, c

har.

100

;(m

edia

l) m

argi

nS

torr

s 19

91, c

har.

69;

Bro

wn

1981

, cha

r. 2

8

145

Pel

vic

Gird

leLa

rge,

ven

tral

Abs

ent (

0), p

rese

nt (

1)S

ues

1987

A la

rge

vent

ral p

late

form

ed b

y th

e is

chiu

m a

nd p

ubis

pubo

-isch

iatic

pla

teis

cha

ract

eris

tic o

f ple

sios

aurs

.

146

Pel

vic

Gird

leM

edia

n pe

lvic

bar

Abs

ent (

0), p

rese

nt (

1)B

row

n 19

81, c

har.

30

Ana

logo

us to

the

med

ian

pect

oral

bar

, the

med

ian

pelv

ic b

ar is

slo

w to

to o

ssify

, as

disc

usse

d by

Bro

wn

(198

1). I

incl

ude

it he

re b

ecau

se m

ost o

f the

taxa

inth

is a

naly

sis

are

adul

ts, a

nd fo

r th

e sa

ke o

fco

mpl

eten

ess.

The

cha

ract

er is

als

o di

fficu

lt to

sco

re;

the

pres

ence

of a

sut

ure

betw

een

the

med

ian

proc

esse

s of

the

pubi

s an

d is

chiu

m c

an o

nly

bede

term

ined

by

artic

ulat

ing

the

two

elem

ents

.

147

Pel

vic

Gird

leT

hyro

id fe

nest

raC

lose

d (0

), o

pen

(1)

Rie

ppel

199

7b, c

har.

102

;cl

osed

or

open

in a

dult

Sto

rrs

1991

cha

r. 7

1

Con

tinue

d


Ap

pen

dix

1. C

ontin

ued.

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

Cha

r. ty

peC

hara

cter

Sta

tes/

Cod

ing

Cita

tion

Rem

arks

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

148

Pel

vic

Gird

leO

btur

ator

fora

men

Pre

sent

(0)

, abs

ent (

1)R

iepp

el 1

997b

, cha

r. 1

01;

The

obt

urat

or fo

ram

en is

lost

in s

ome

pist

osau

roid

sS

torr

s 19

91, c

har.

70

and

all p

lesi

osau

rs; s

ee d

iscu

ssio

n ab

ove.

149

Pel

vic

Gird

leIl i

ac b

lade

Wel

l-dev

elop

ed (

0), r

educ

ed (

1)R

iepp

el 1

994a

, 199

7b,

char

s. 7

9, 9

9; S

torr

s 19

91,

char

. 67;

Bro

wn

1981

, cha

r.31

; Sue

s 19

87

150

Hum

erus

Ang

led

hum

erus

Abs

ent (

1), p

rese

nt (

0)R

iepp

el 1

994a

, 199

7b,

The

ang

led

hum

erus

is c

hara

cter

istic

of s

tem

-gro

upch

ars.

74,

92;

Sto

rrs

saur

opte

rygi

ans,

and

of e

arly

ple

sios

aurs

. See

Sto

rrs

1991

cha

r. 7

3(1

997)

for

the

cond

ition

in P

lesi

osau

rus .

151

Pro

-pod

ials

Exp

ande

d di

stal

Abs

ent (

0), p

rese

nt (

1)S

hort

pro

podi

als

who

se d

ista

l end

s ar

e ex

pand

edpr

opod

ials

with

dor

sal

ante

ro-p

oste

riorly

and

flat

tene

d do

rso-

vent

rally

are

troc

hant

er/ t

uber

osity

char

acte

ristic

of a

ll pl

esio

saur

s. T

he p

osse

ssio

n of

ado

rsal

troc

hant

er o

r tu

bero

sity

is a

lso

char

acte

ristic

of

all p

lesi

osau

r pr

opod

ials

.

152

Hum

erus

Dis

tal e

nd o

f hum

erus

Abs

ent (

0), p

rese

nt (

1)Ill

ustr

ated

by

Will

isto

nT

he h

umer

us in

man

y pl

esio

saur

oids

has

two

dist

inct

has

two

dist

inct

1906

plan

es o

r fa

cets

on

its d

ista

l end

, with

whi

ch th

epl

anes

in a

dult

epip

odia

ls a

rtic

ulat

e.

153

Pro

podi

als

Dis

tinct

face

t on

dist

alA

bsen

t (0)

, pre

sent

(1)

Illus

trat

ed b

y W

illis

ton

Tric

leid

us a

nd P

olyc

otyl

us h

ave

a th

ird d

istin

ct fa

cet

hum

erus

for

1906

on th

e po

ster

o-di

stal

end

of t

he h

umer

us w

hich

supe

rnum

ery

artic

ulat

es w

ith a

sup

ernu

mer

y os

sific

atio

n of

the

ossi

ficat

ion

epip

odia

l row

.

154

Pro

podi

als

Gra

cile

or

mas

sive

Gra

cile

/con

stric

ted

(0),

mas

sive

(1)

Bro

wn

1981

, cha

r. 3

2A

pplic

able

onl

y to

ple

sios

aurs

.

155

Pro

podi

als

Pro

podi

als

rela

tivel

yN

ot e

long

ate

(0),

elo

ngat

e w

ith n

arro

wLa

te p

liosa

urs

such

as

Bra

chau

chen

ius

have

long

,el

onga

tedi

stal

hea

d (1

)na

rrow

pro

podi

als

com

pare

d to

ear

lier

plio

saur

s.

156

Hum

erus

Del

tope

ctor

al c

rest

Pre

sent

(0)

, abs

ent (

1)R

iepp

el 1

997b

, cha

r. 9

3


7U

lna

Uln

ar s

hape

Nar

row

(0)

or

broa

d (1

) di

stal

lyS

ande

r et

al 1

997;

A b

road

dis

tal u

lna

is th

ough

t to

be a

syn

apom

orph

yS

torr

s 19

91, c

har.

83

of A

gust

asau

rus

and

Pis

tosa

urus

(S

ande

r et

al.

1997

);ho

wev

er I

bel ie

ve it

form

s pa

rt o

f a tr

ansf

orm

atio

nse

ries

of d

ecre

asin

g pe

richo

ndra

l oss

ifica

tion

inpi

stos

auro

ids

and

ples

iosa

urs.

I ha

ve th

eref

ore

code

dit

as p

rese

nt in

ple

sios

aurs

rat

her

than

inap

plic

able

.

158

Uln

aD

istin

ctly

luna

te u

lna

Abs

ent (

0), p

rese

nt (

1)M

any

early

ple

sios

aurs

hav

e an

uln

a w

hich

isdi

stin

ctly

luna

te in

sha

pe.

159

Fem

urIn

tern

al tr

ocha

nter

Wel

l-dev

elop

ed (

0), r

educ

ed (

1)R

iepp

el 1

997b

, cha

r. 1

05B

oth

this

cha

ract

er a

nd c

hara

cter

160

are

rel

ated

toth

e pr

ogre

ssiv

e lo

ss o

f fem

oral

feat

ures

as

saur

opte

rygi

ans

beca

me

mor

e aq

uatic

.

160

Fem

urIn

ter-

troc

hant

eric

foss

aD

eep

(0),

dis

tinct

but

red

uced

(1)

,R

iepp

el 1

997b

, cha

r. 1

06ru

dim

enta

ry o

r ab

sent

(2)

161

Epi

-pod

ials

Epi

podi

al m

orph

olog

yLo

nger

than

bro

ad (

0), e

qual

or

broa

der

Bro

wn

1981

, cha

r. 3

5.;

than

long

(1)

Sue

s 19

87

162

Epi

-pod

ials

Sup

ernu

mer

yN

one

(0),

epi

podi

al r

ow/p

isifo

rm (

1),

Mod

ified

from

Sto

rrs

Ple

sios

aurs

ofte

n ha

ve a

sup

ernu

mer

y os

sific

atio

n in

ossi

ficat

ions

, for

elim

bpr

opod

ial (

2), b

oth

(3)

1991

,cha

r. 8

4; B

row

nth

e ep

ipod

ial r

ow a

nd/o

r on

a le

vel w

ith th

e di

stal

1981

, cha

r. 3

4pr

opod

ial.

The

se b

ones

are

slo

w to

oss

ify a

nd a

relia

ble

to lo

ss d

urin

g co

llect

ion.

163

Met

a-po

dial

sF

ifth

met

apod

ial

In li

ne w

ith r

est o

f met

apod

ial r

ow (

0),

Ow

en 1

865,

Bro

wn

Ow

en (

1865

) w

as th

e fir

st to

not

e th

at th

e fif

thsh

ifted

into

dis

tal m

esop

odia

l row

1981

, cha

r. 3

7m

etap

odia

l is

shift

ed in

to th

e di

stal

mes

opod

ial r

ow in

all p

lesi

osau

rs. T

his

shift

res

ults

in a

mis

alig

nmen

t of

the

phal

ange

al a

rtic

ulat

ions

of d

igit

five

rela

tive

to th

eot

her

digi

ts.

164

Pha

lang

esH

yper

phal

angy

No

incr

ease

(2–

3–4–

5–3)

(0)

,M

odifi

ed fr

om S

torr

shy

perp

hala

ngy

pres

ent (

1)19

91, c

har.

80

165

Pha

lang

esIn

terlo

ckin

g di

stal

Abs

ent (

0), p

rese

nt (

1)T

he p

hala

nges

of T

rinac

rom

erum

and

rel

ated

taxa

phal

ange

s an

terio

r to

have

join

ts w

hich

are

mis

alig

ned

betw

een

digi

ts in

fifth

pha

lang

eal r

owdi

gits

one

thro

ugh

four

. Thi

s ch

arac

ter

is d

ifficu

lt to

scor

e du

e to

con

cern

s ov

er p

rese

rvat

ion.

166

Rib

sM

edia

n ga

stra

l rib

Alw

ays

one

late

ral p

roce

ss (

0), m

ayR

iepp

el 1

997b

, cha

r. 1

19el

emen

tha

ve tw

o la

tera

l pro

cess

es (

1)—

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

——

—


Appendix 2. Data matrix for the cladistic analysis in this paper. The first three taxa comprise the outgroup.Inapplicable characters are coded as ‘x’; unknown characters are coded as ‘?’. The ancestral condition isgenerally coded as ‘0’.————————————————————————————————————————————————Taxon 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19————————————————————————————————————————————————Simosaurus 0 0 0 0 2 2 x 0 0 0 0 ? 0 1 2 0 0 0 ?Cymatosaurus 0 ? ? ? ? 2 x 0 1 0 0 ? 0 0 1,2 1 0 1 ?Pistosauridae 0 0 ? 1 ? 0 x 1 0 0 0 ? 0 0 1 1 0 1 ?Calawayasaurus 2 1 2 0 2 0 0 0 0 0 0 0 0 0 x 0 1 1 ?Attenborosaurus 1 0 1 1 0 0 0 1 1 0 0 ? ? 0 0 ? 0 ? ?BMNH R.5488 1 0 1 1 1 0 1 1 1 0 ? 0 1 0 ? ? 0 0 1Brachauchenius 1 2 ? ? ? 1 ? 2 1 0 1 1 0 x x 0 0 0 0Brancasaurus 2 1 2 1 0 0 0 0 0 0 0 0 0 1 x 0 0 1 ?Cryptoclidus 2 0 0 1 2 0 1 0 0 0 0 0 0 0 x 0 0 0 1Dolichorhynchops 1 2 1 1 0 1 1 2 0 0 1 0 0 x x 0 0 0 ?Eurycleidus 0 ? 0 ? ? 0 0 1 1 0 0 ? 0 0 0 1 0 0 ?Hauffiosaurus 1 0 2 1 0 1 0 2 1 0 ? ? ? ? ? ? ? ? ?Kimmerosaurus ? ? ? ? ? 2 ? 3 0 0 0 ? ? 0 x 0 ? 0 ?Kronosaurus 1 2 2 1 ? 1 ? 2 ? ? ? ? ? ? ? ? ? ? ?Leptocleidus ? 2 ? 1 ? 0 1 1 1 0 1 0 1 x x 0 0 0 ?Libonectes 2 1 ? 0 ? 0 0 0 0 0 2 0 0 x x ? 1 ? ?Liopleurodon 1 2 1 1 1 1 1 2 2 0 1 1 0 x x 0 0 0 1Macroplata 1 0 2 1 0 1 0 2 0 0 ? 1 0 x 0 0 ? ? 0Microcleidus 2 1 0 1 0 0 0 0 0 0 0 0 0 ? ? 0 ? 1 ?MOR 751 0 2 ? ? ? 0 1 1 0 0 0 1 0 0 x 0 0 0 1Morturneria ? ? ? ? ? 2 1 3 0 0 ? ? ? ? ? ? ? ? ?Muraenosaurus 2 1 0 1 2 0 1 0 0 0 0 0 0 0 x 0 0 0 0Peloneustes 1 2 1 1 1 1 1 2 1 0 1 1 0 x x 0 0 0 1Plesiosaurus 0 0 2 1 0 0 0 0 0 0 0 0 0 0 ? 1 0 0 0Pliosaurus 1 2 ? ? ? 1 ? 2 2 0 1 1 0 x x 0 0 0 ?Polycotylus ? 2 1 1 0 ? 1 ? ? ? ? ? ? ? ? ? ? ? ?Rhomaleo. megaceph. 0 0 0 1 0 0 0 1 1 0 0 1 0 0 x 1 0 0 1Rhomaleo. victor 1 0 0 1 2 0 0 1 1 ? ? 0 ? ? ? ? ? ? ?Rhomaleo. zetland. 0 2 ? ? 0 1 ? 1 1 0 1 0 1 x ? 0 0 0 1Simolestes 1 2 1 1 1 0 1 1 1 0 1 0 ? x x 0 ? ? ?Styxosaurus 2 1 ? ? ? 0 0 0 0 0 2 0 ? x ? 0 1 0 ?Thalassiodracon 0 0 0 1 0 0 0 1 1 0 0 0 0 0 0 1 0 0 1Tricleidus 2 0 ? 1 0 2 1 0 0 0 0 0 0 0 x ? ? 0 ?Trinacromerum 1 2 1 1 1 1 1 2 0 0 1 0 0 x x 0 ? 0 ?————————————————————————————————————————————————


————————————————————————————————————————————————20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41————————————————————————————————————————————————

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 00 0 0 0 0 1 0 0 0 0 1 0 0 0 1 1 0 0 0,1 0 0 01 0 0 0 0 2 0 1 0 1 1 0 0 0 ? 1 0 0 1 0 1 01 1 0 0 0 2 1 1 1 1 2 0 0 0 1 2 x 0 x 1 1 11 0 0 0 0 2 0 1 0 1 1 0 0 0 ? 1 0 ? 0 ? 0 01 ? 0 0 0 2 ? 1 ? 1 0 0 ? 0 ? 1 0 1 ? 0 0 ?1 0 0 0 0 2 0 1 1 1 0 0 1 0 1 1 1 0 0 1 0 01 1 0 0 0 2 1 1 0 1 2 0 0 0 1 2 x 0 x 1 1 11 1 0 0 0 2 1 1 0 1 2 0 0 1 1 2 x 0 x 1 1 01 0 0 0 1 2 1 1 0 1 2 0 0 0 1 2 x 0 x 1 1 21 0 0 0 0 2 0 1 0 1 ? 0 ? 0 1 ? ? 0 ? 0 ? ?? ? ? ? ? ? ? ? ? 1 ? ? ? 0 1 ? ? ? ? ? ? 01 1 ? 0 0 2 1 1 ? 1 ? ? ? 1 1 ? x ? ? ? 1 ?? ? ? ? ? ? 0 1 ? 1 ? ? 1 ? 1 ? ? ? ? ? ? ?1 0 0 0 0 2 0 1 0 1 0 0 ? 0 1 ? ? ? ? 0 ? 11 1 0 0 ? 2 1 ? 1 1 2 0 0 0 1 2 x 0 x 1 1 ?1 0 0 0 0 2 0 1 0 1 0 0 1 0 1 1 0 0 0 0 0 01 0 0 0 0 2 0 1 ? 1 0 0 1 0 1 1 0 1 0 0 ? ?1 1 ? 0 0 2 1 1 ? 1 ? 0 ? 0 1 2 x 0 x ? 1 11 0 0 0 0 2 1 1 0 1 2 0 0 0 1 2 x 0 x 1 1 2? ? ? ? ? ? ? 1 1 1 ? ? ? ? 1 ? x ? ? ? x ?1 1 ? 0 0 2 1 1 0 1 2 0 0 ? ? ? x 0 ? ? 1 ?1 0 0 0 0 2 0 1 0 1 0 0 1 0 1 1 0 0 0 0 0 01 0 0 0 0 2 0 1 0 1 1 0 0 0 1 2 0 0 x 1 1 11 0 0 0 0 2 ? 1 1 1 0 0 1 0 1 1 1 0 ? ? 0 0? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? x ? ? ? ? ?1 0 0 0 0 2 0 1 ? 1 0 0 ? 0 1 1 0 1 0 0 ? 1? ? ? 0 0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?1 0 0 0 0 2 0 1 ? 1 0 0 1 0 1 1 0 1 0 0 0 ?1 0 0 0 0 2 0 1 ? 1 0 0 1 0 1 1 0 ? 0 ? ? ?? ? 0 0 0 2 1 1 1 1 2 0 0 0 1 2 x 0 x 1 1 11 0 0 0 0 2 0 1 0 1 1 0 0 0 1 1 0 0 0 0 1 11 0 0 0 0 2 1 1 ? 1 2 0 0 1 1 2 x 0 x ? 1 01 ? 0 0 1 2 1 1 0 1 2 0 0 0 1 2 x 0 x 1 1 2

————————————————————————————————————————————————Continued


————————————————————————————————————————————————Taxon 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60————————————————————————————————————————————————Simosaurus 0 0 0 0 x 0 x x 0 0 0 x 0 x 0 0 0 0 0Cymatosaurus ? ? 1 1 ? ? ? ? ? ? ? ? 0 x ? ? 2 0 0Pistosauridae ? ? 1 ? ? ? ? ? ? ? 1 ? 0 0 ? ? ? 0 0Calawayasaurus 0 0 1 1 0 2 0 1 1 1 ? ? 0 0 1 1 1 1 0Attenborosaurus ? ? 1 ? 0 ? ? ? ? ? ? ? 1 1 ? ? 2 0 ?BMNH R.5488 0 1 1 ? 1 ? 0 ? ? ? 0 0 ? 1 1 0 1 ? ?Brachauchenius ? ? 1 ? 1 ? 0 ? ? ? 1 1 1 1 ? ? 1 0 0Brancasaurus 0 0 1 ? 0 ? 0 ? ? ? ? ? 0 0 1 1 1 ? 0Cryptoclidus 1 1 1 ? 0 1 0 0 ? 0 ? ? 1 0 1 1 1 0 2Dolichorhynchops 0 0 1 1 0 1 1 1 0 0 0 0 1 0 1 1 1 0 2Eurycleidus 0 1 1 1 0 0 ? ? 0 0 ? ? 1 1 1 0 1 0 2Hauffiosaurus ? 1 ? ? ? ? ? ? 0 0 ? ? 1 ? ? ? 2 0 0Kimmerosaurus 1 1 1 1 0 0 0 0 ? 0 ? ? 1 0 1 1 1 0 2Kronosaurus ? 1 1 1 0 2 0 1 0 0 ? ? ? 1 ? ? 2 0 0Leptocleidus 0 ? 1 ? ? ? ? 1 0 ? 0 0 1 1 ? ? 1 1 2Libonectes 0 0 1 1 0 2 0 1 1 1 1 ? 0 0 1 1 1 1 0Liopleurodon 0 1 1 0 1 0 0 1 1 0 0 1 1 1 ? 0 2 0 1Macroplata 0 1 1 1 0 0 0 0 0 0 ? 0 ? 1 ? ? 1 0 0Microcleidus ? ? ? ? ? ? ? ? ? ? ? ? ? 0 ? ? ? 1 0MOR 751 0 0 1 1 1 ? ? ? ? 0 ? ? ? 0 ? 1 1 0 2Morturneria 0 0 ? 1 1 0 ? 1 ? ? ? ? 1 ? ? 1 ? ? ?Muraenosaurus 0 1 1 ? 0 ? 0 ? ? ? ? ? 1 0 ? 1 1 0 2Peloneustes 0 1 1 0 0 0 0 1 1 0 0 1 1 1 1 0 2 0 0Plesiosaurus ? 0 1 ? 0 ? ? ? ? 1 1 1 1 0 0 0 1 0 1Pliosaurus 0 1 1 ? 1 ? ? 1 ? ? 0 0 1 1 ? ? 2 0 ?Polycotylus ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Rhomaleo. megaceph. ? 1 1 1 1 ? 0 1 0 1 0 0 ? 1 ? ? 1 1 2Rhomaleo. victor ? 0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1 1 2Rhomaleo. zetland. ? 1 1 ? 1 1 1 1 0 1 0 0 1 1 ? ? 1 1 2Simolestes 0 1 1 ? 1 0 0 1 ? ? 0 0 1 1 ? 0 1 ? ?Styxosaurus ? ? 1 ? ? ? ? ? ? 1 1 0 0 0 1 1 ? ? ?Thalassiodracon 0 1 1 1 0 0 0 0 0 1 1 ? 1 1 0 0 1 0 2Tricleidus 0 0 1 1 0 1 1 0 0 0 ? ? 1 0 ? ? 1 0 2Trinacromerum ? 0 1 ? 0 1 1 ? 0 ? 0 0 1 0 ? ? 1 1 2————————————————————————————————————————————————

Appendix 2. Continued.


————————————————————————————————————————————————61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82————————————————————————————————————————————————

0 x x x 0 0 0 x x ? x x x x 0 x 0 0 0 0 0 00 x x x 0 0 ? x x ? x x x x ? x 0 0 0 0 1 01 0 x x 0 ? 0 0 0 ? 1 0 ? 0 ? ? 0 0 0 0 0 01 1 0 0 0 1 0 0 0 0 1 2 1 ? 0 0 0 0 0 0 1 01 0 1 x 0 0 0 0 1 0 0 2 0 0 0 0 1 ? ? ? ? 11 1 1 ? 0 0 0 0 0 0 0 2 x 0 ? 0 ? ? ? ? ? ?1 1 1 0 0 0 0 0 3 0 2 2 x 0 ? 0 ? 0 ? 1 ? 11 ? ? 0 ? ? 0 0 ? 0 ? ? 1 0 ? 0 0 ? 0 0 1 ?1 0 0 x 0 1 0 0 0 1 0 2 1 0 0 0 0 0 0 0 ? 01 2 0 0 0 1 1 1 0 1 0 2 1 1 0 1 0 0 0 0 1 01 0 1 x 0 0 0 0 0 0 2 2 0 0 0 0 ? ? 0 0 ? ?1 1 1 0 1 0 0 0 2 0 2 2 x 0 ? 0 0 0 0 0 1 01 0 0 x 0 ? 0 1 0 ? 0 2 1 1 ? 0,1 ? ? ? 0 ? ?1 1 ? 0 ? ? ? 0 2 ? ? ? x 0 ? 0 0 ? ? ? ? ?1 1 1 1 0 0 0 0 0 0 1 2 x 0 0 0 1 ? ? 0 1 11 2 0 0 0 1 0 0 0 0 1 2 1 ? 0 0 0 ? 0 0 1 01 1 1 0 0 0 0 0 3 0 2 2 x 0 ? 0 0 1 1 1 1 11 0 1 x ? ? 0 0 0 0 2 2 0 0 ? 0 ? ? 0 0 1 ?1 0 1 0 0 ? 0 0 0 0 ? 2 1 0 0 ? ? 0 ? ? ? 01 1 0 0 0 1 1 1 0 1 ? 2 1 ? ? ? 0 ? ? ? ? 01 ? 0 x ? ? 0 ? ? 1 ? 2 ? 1 0 1 ? ? 0 ? 1 ?1 0 0 x 0 1 0 0 0 1 0 1 1 0 0 0 0 0 1 0 0 01 1 1 0 1 0 0 0 2 0 2 2 x 0 0 0 1 0 0 0 1 11 0 0 x 0 0 0 0 0 0 ? 1 ? 0 0 0 0 ? 0 0 0 01 1 ? 0 ? ? 0 ? 3 ? ? ? x ? ? 0 ? ? 1 ? 1 ?? ? ? 0 ? ? ? ? ? ? ? ? 1 1 ? ? ? ? ? ? ? ?1 1 1 1 0 0 0 0 0 0 1 2 x 0 0 0 ? 1 0 0 1 11 1 1 1 0 ? 0 0 ? ? 1 1 x ? ? 0 ? 1 1 0 1 01 ? 1 ? 0 ? 0 0 0 0 ? 2 x 0 ? ? ? ? ? ? ? ?1 1 1 ? 0 0 0 0 0 0 ? 2 x 0 ? 0 ? 1 ? ? ? ?? ? ? 0 ? ? ? 0 ? ? ? ? ? ? ? ? 0 ? ? ? ? ?1 0 1 x 0 0 0 0 0 0 2 2 0 0 0 0 0 ? ? 0 1 ?1 0 0 x 0 1 0 1 0 1 0 2 1 1 0 1 ? ? ? 0 0 ?1 2 0 0 0 ? 1 1 0 1 0 2 1 1 ? 1 0 0 ? ? ? 0

————————————————————————————————————————————————Continued


————————————————————————————————————————————————Taxon 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101————————————————————————————————————————————————Simosaurus 0 0 x 0 0 0 0 0 0 0 0 ? 0 0 0 0 0 x 0Cymatosaurus 1 1 0 0 ? ? 2 ? ? ? ? ? ? ? ? ? 1 ? 1Pistosauridae 0 1 ? 0 ? ? 1 ? ? ? ? ? ? ? ? ? 0 x 1Calawayasaurus 1 0 x 1 1 0 1 0 0 0 0 ? 0 0 0 1 0 x 0Attenborosaurus ? 0 x 0 0 1 2 1 ? 0 0 ? ? 0 0 0 1 ? 0BMNH R.5488 ? ? ? 1 ? 1 2 1 ? ? ? ? ? ? ? 0 1 ? ?Brachauchenius 1 1 0 0 0 ? 2 1 ? 1 ? ? 0 ? 0 0 1 ? 0Brancasaurus 1 ? ? 0 ? 0 ? ? ? ? ? ? ? ? ? ? 0 x 0Cryptoclidus 0 0 x 0 1 0 0 0 0 0 0 0 1 0 1 0 0 x 0Dolichorhynchops 0 0 x 0 x 0 3 2 0 0 0 0 1 0 1 1 0 x 0Eurycleidus 0 0 x 0 1 1 2 1 ? ? 0 ? 0 0 0 0 1 1 ?Hauffiosaurus 1 1 1 0 ? 0 3 1 0 ? ? ? ? ? 0 0 1 1 0Kimmerosaurus ? 0 x ? ? 0 0 0 ? 0 1 0 1 ? 1 1 ? ? 0Kronosaurus ? 1 ? ? ? 0 3 ? ? ? ? ? ? ? ? ? ? ? ?Leptocleidus 0 1 0 1 ? ? 2 ? 0 1 0 1 0 0 0 0 1 1 1Libonectes 1 0 x ? 1 0 1 0 1 0 0 0 0 0 0 1 0 x 0Liopleurodon 1 1 1 0 1 0 2 1 0 1 0 1 0 0 0 0 1 1 0Macroplata 1 0 x 0 0 0 3 1 ? 1 ? ? ? 0 0 0 ? ? 0Microcleidus ? 0 x 0 1 0 1 0 ? 0 ? 0 0 ? 0 1 0 x 0MOR 751 ? 0 x 0 x 0 2 1 0 0 0 ? 1 0 1 1 0 x 0Morturneria ? ? ? 0 1 0 ? ? ? ? ? 0 ? ? 0 1 0 x 0Muraenosaurus 1 0 x 0 1 0 0 0 0 0 0 0 1 0 1 0 0 x 0Peloneustes 1 1 2 0 0 0 3 1 0 1 0 1 0 0 0 0 1 1 0Plesiosaurus 0 0 x 0 ? 0 0 ? ? ? ? 0 0 ? 0 0 0 x 0Pliosaurus 1 1 ? 0 0 0 2 1 0 1 0 1 1 0 0 0 1 1 0Polycotylus ? ? ? ? x 0 ? ? 0 ? 0 0 1 0 1 1 ? ? ?Rhomaleo. megaceph. ? 1 1 1 0 1 2 1 1 ? ? ? ? ? 0 0 1 ? 1Rhomaleo. victor 0 1 ? ? 0 1 2 1 1 ? ? ? ? 0 0 0 ? ? 1Rhomaleo. zetland. ? ? ? 1 0 1 2 1 ? ? 0 ? 0 0 0 0 1 ? 1Simolestes ? 1 ? ? 0 1 2 1 ? 1 0 1 0 0 0 0 ? ? 1Styxosaurus ? ? ? 1 ? 0 1 ? ? 0 ? ? 0 ? ? 1 0 x 0Thalassiodracon 1 0 x 0 ? 0 2 1 ? ? ? ? 0 ? 0 0 0 x 0Tricleidus 0 0 x 0 1 0 0 0 0 0 0 0 ? 0 1 1 0 x 0Trinacromerum ? 0 x 0 ? 0 3 2 ? 0 ? 0 1 0 1 1 0 x 0————————————————————————————————————————————————



————————————————————————————————————————————————102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124————————————————————————————————————————————————

0 0 0 ? 0 0 ? ? ? 0 0 0 0 0 0 0 0 x 0 0 0 ? 01 0 0 ? 0 0 ? ? ? ? ? ? 0 0 ? ? ? x ? ? ? ? ?0 ? 0 ? 0 0 ? ? ? 0 0 0 0 0 0 0 1 0 1 1 0 0 01 0 0 ? 0 0 ? ? ? 3 1 1 ? 0 1 1 1 0 2 1 0 ? 00 1 0 0 0 0 ? ? ? 0 0 0 ? 0 0 0 1 ? 2 ? 0 0 00 1 0 0 1 ? 0 1 0 0 2 0 1 0 0 0 1 0 1 ? 0 ? 00 1 0 ? ? ? ? ? ? 2 2 ? ? 0 0 1 1 1 2 ? 0 ? 00 0 0 ? 0 ? ? 1 0 1 1 ? ? 0 0 1 1 0 2 1 0 ? 00 0 0 0 1 0 1 0 1 0 0 1 0 0 0 1 1 0 2 0 1 1 10 0 0 ? 0 0 1 1 2 2 2 1 ? 0 0 1 1 0 2 1 0 ? 10 0 0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?0 0 0 ? 2 1 ? ? ? 0 0 0 ? 0 0 0 ? 0 2 ? 0 ? ?0 2 0 ? 3 2 1 ? ? ? 2 ? 0 0 0 1 1 0 2 ? 1 1 ?0 1 ? ? ? ? ? 1 ? 2 2 ? ? ? ? 1 1 ? 2 ? 0 ? 00 1 0 0 0 0 ? ? ? 2 2 0 1 0 0 1 1 0 2 0 0 ? 01 0 0 ? 0 0 1 ? 0 3 1 1 ? 1 1 1 1 0 2 1 1 ? 00 1 0 1 0 1 ? ? ? 2 2 0 0 0 0 0 1 1 2 1 0 1 00 0 0 0 ? 1 0 ? 0 0 0 ? 1 0 0 0 1 0 2 0 0 ? 0? 0 0 0 ? ? 0 ? ? 1 1 1 0 1 1 0 1 0 2 ? 1 0 01 1 0 ? 1 0 1 1 2 2 2 ? 1 0 0 1 1 0 ? ? 0 ? ?0 2 0 ? 2 2 0 0 2 ? 2 ? ? 0 1 1 1 0 2 ? 0 ? ?0 0 0 0 0 0 1 0 1 1 1 0 0 0 ? 1 1 0 2 1 1 1 10 1 0 0 1 1 0 0 0 2 2 0 1 0 0 0 1 0 2 0 0 1 00 0 0 0 0 ? ? ? 0 1 0 ? 0 0 0 0 1 0 2 1 0 0 00 1 1 1 1 1 ? ? ? ? 2 ? 0 0 0 0 1 1 2 ? 0 ? 0? 1 0 ? ? ? 1 1 2 2 2 0 ? 0 0 1 1 0 1 1 0 ? 10 1 0 0 0 ? ? ? ? 0 2 ? 1 0 0 0 1 0 1 ? 0 0 00 1 0 ? ? ? ? ? ? 0 ? 0 ? 0 0 ? ? 0 ? ? 0 0 ?0 1 0 0 ? ? ? ? ? 2 2 0 1 0 0 0 1 0 1 ? 0 ? 00 1 0 0 0 ? ? ? 0 2 2 ? 0 0 0 0 1 0 1 1 0 1 01 0 0 ? 0 ? ? ? ? 3 1 ? ? 1 1 1 1 0 2 1 1 ? 00 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 2 0 0 0 00 0 0 0 0 ? 1 ? 1 0 0 1 0 0 0 1 1 0 2 1 0 1 10 0 0 ? 0 1 1 1 2 2 2 1 ? 0 0 1 1 0 2 1 0 ? 1

————————————————————————————————————————————————Continued


————————————————————————————————————————————————Taxon 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143————————————————————————————————————————————————Simosaurus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x x x 0Cymatosaurus ? 0 ? ? ? ? ? ? ? ? ? ? ? ? ? x ? ? ?Pistosauridae 0,1 1 0 0 1,2 0 ? 1 0 ? 0 0 0 1 1 x 0 0 0Calawayasaurus 1 1 1 1 2 1 ? 0 0 0 1 0 0,1 1 1 0 1 1 1Attenborosaurus 0 1 1 1 0 0 ? 0 0 0 0 0 0 1 1 0 0 1 1BMNH R.5488 0 1 1 1 ? 0 ? 0 0 0 0 0 1 1 1 0 0 0 1Brachauchenius 1 1 1 1 2 0 ? ? ? ? ? ? ? ? ? ? ? ? ?Brancasaurus 0 1 1 1 2 1 1 0 0 0 1 ? 2 1 1 0 1 1 1Cryptoclidus 1 1 1 1 2 1 ? 0 0 0 1 1 2 1 1 0 0 1 1Dolichorhynchops 1 1 1 1 2 0 x 0 0 2 0 1 1 1 1 1 0 1 1Eurycleidus ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 0 ? ? 1Hauffiosaurus ? ? 1 1 ? 0 ? 0 ? ? 0 0 ? 1 1 0 0 1 1Kimmerosaurus 1 ? ? 1 ? 0 ? ? ? ? ? ? ? ? ? ? ? ? ?Kronosaurus 0 ? 1 1 2 0 ? ? ? ? 0 ? 0 1 1 ? 0 ? ?Leptocleidus 0 1 1 1 ? 0 0 0 0 0 0 0 1 1 1 0 0 1 ?Libonectes 1 ? 1 1 ? 1 ? 0 0 0 2 0 2 1 1 ? 1 1 ?Liopleurodon 0 1 1 1 2 0 ? 0 ? ? 0 ? ? 1 1 0 0 1 1Macroplata 0 ? 1 1 0 0 ? ? ? ? ? ? ? ? 1 ? ? ? 1Microcleidus 1 1 1 1 2 1 ? 0 ? ? 1 ? 2 ? 1 0 0 1 1MOR 751 ? ? 1 1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Morturneria ? ? 1 1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Muraenosaurus 1 1 1 1 2 1 ? 0 0 1 1 1 2 1 1 0 0 1 1Peloneustes 0 1 1 1 2 0 0 0 ? ? 0 0 0 1 1 0 0 1 1Plesiosaurus 1 1 1 1 2 1 ? 0 1 0 0 0 1 1 1 0 0 1 1Pliosaurus 0 1 1 1 ? 0 ? ? ? ? ? ? ? ? ? 0 ? ? 1Polycotylus 1 1 1 1 2 0 x 0 0 2 0 1 1 1 1 1 ? ? 1Rhomaleo. megaceph. 0 1 1 1 2 0 ? 0 ? ? ? ? ? ? 1 ? 0 ? 1Rhomaleo. victor ? ? ? 1 2 ? ? ? 0 ? 0 0 1 1 1 0 0 1 ?Rhomaleo. zetland. ? 1 1 1 ? 0 ? ? ? ? ? ? ? ? ? ? ? ? ?Simolestes ? 1 1 1 ? 0 ? 0 ? ? 0 ? 0 1 1 0 0 0 1Styxosaurus 1 ? 1 1 2 1 ? ? ? ? ? ? ? ? ? ? ? ? ?Thalassiodracon 0 1 1 1 2 0 ? 0 0 0 0 0 1 1 1 0 0 1 1Tricleidus 1 1 1 1 2 0 0 0 0 2 1 0 2 1 1 0 0 1 1Trinacromerum 1 1 1 1 2 0 x 0 0 2 0 1 1 1 1 1 0 1 1————————————————————————————————————————————————



————————————————————————————————————————————————144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166————————————————————————————————————————————————

0 0 x 0 0 0 0 0 x 0 x x 0 0 0 1 2 0 0 0 0 0 11 ? ? 1 ? ? 0 0 x ? x x ? ? ? 0 1 ? ? ? ? ? 0? 1 x ? 1 1 0 0 x 0 x x 1 1 0 1 ? 0 0 0 ? ? 00 1 0 1 1 1 1 1 0 0 1 0 1 1 0 1 2 1 0 1 1 1 ?1 1 0 1 1 1 0 1 0 0 0 0 1 1 1 1 2 0 0 1 1 0 01 1 1 1 1 1 0 1 ? 0 0 0 1 1 1 1 2 0 ? ? 1 ? 0? ? ? ? ? ? 1 1 ? ? 0 1 ? ? 0 ? ? 1 ? 1 1 ? ?0 1 1 1 1 1 1 1 ? ? 0 0 1 ? 0 1 2 1 ? 1 1 ? 01 1 0 1 1 1 1 1 1 0 0 0 1 1 0 1 2 1 1 1 1 0 01 1 0 1 1 1 1 1 1 0 0 0 1 1 0 1 2 1 3 1 1 1 ?1 1 0 1 1 1 ? 1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?1 1 ? 1 1 ? 1 1 0 0 0 0 1 1 1 1 2 0 2 1 1 0 0? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?1 1 1 1 1 ? ? 1 ? ? 0 0 ? ? 0 1 2 1 ? ? 1 ? ?? ? ? ? ? ? 1 1 0 0 ? 0 1 ? ? ? ? ? ? ? 1 ? ?? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?1 1 1 1 1 1 1 1 0 0 0 0 1 1 0 1 2 1 0 1 1 0 01 1 1 1 1 ? 1 1 0 0 0 0 1 1 ? 1 2 0 ? ? 1 ? ?1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 2 0 1 1 1 0 0? ? ? ? ? ? 1 1 1 1 0 0 1 1 0 1 2 1 ? 1 1 1 ?? ? ? ? ? ? 1 1 ? ? ? ? ? ? ? ? ? 1 ? ? 1 ? ?1 1 0 1 1 1 1 1 1 1 0 0 1 1 0 1 2 1 1 1 1 0 01 1 0 1 1 1 1 1 0 0 0 0 1 1 0 1 2 1 0 1 1 0 01 1 1 1 1 1 0 1 0 0 0 0 1 1 1 1 2 0 1 1 1 0 01 1 0 1 1 ? 1 1 0 0 0 1 1 1 0 1 2 1 ? ? 1 ? 01 1 0 1 1 1 1 1 1 1 0 0 1 1 0 1 2 1 3 1 1 ? 01 1 ? 1 1 1 0 1 0 0 0 0 1 1 1 1 2 0 ? ? 1 ? 01 1 1 1 1 ? 0 1 0 0 0 0 1 1 1 1 2 0 3 1 1 0 0? 1 ? ? ? ? 0 1 0 0 0 0 1 1 1 1 2 0 ? ? 1 ? ?1 1 1 1 1 1 1 1 1 0 0 0 1 1 0 1 2 0 0 ? 1 ? ?? ? ? ? ? ? ? 1 ? 0 ? ? ? ? ? ? ? ? ? ? ? ? ?1 1 1 1 1 1 0 1 0 0 0 0 1 1 1 1 2 0 0 1 1 0 01 1 0 1 1 ? 1 1 1 1 0 0 1 1 0 1 2 1 2 1 1 ? 01 1 0 1 1 1 1 1 1 0 0 0 1 1 0 1 2 1 3 1 1 1 0

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A cladistic analysis and taxonomic revision of the ...

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