625

REVIEWS

J. Paleont., 79(3), 2005, pp. 625–627Copyright q 2005, The Paleontological Society0022-3360/05/0079-625$03.00

Posture, Locomotion, and Paleoecology of Pterosaurs. SankarChatterjee and R. J. Templin. 2004. The Geological Society ofAmerica, Special Paper 376, Boulder, Colorado, 64 1 iv p. ISBN0-8137-2376-0; Evolution and Palaeobiology of Pterosaurs.2003. Eric Buffetaut and Jean-Michel Mazin, eds. Geological So-ciety, London, Special Publications 217, London, 347 p. ISBN 1-8623-9143-2.

In the past year, two books about pterosaurs have been pub-lished: Posture, Locomotion, and Paleoecology of Pterosaurs byChatterjee and Templin and Evolution and Palaeobiology ofPterosaurs edited by Buffetaut and Mazin. Although both booksinclude broad coverage of the present knowledge of pterosaurs,they are very different in approach and not equally successful.

Chatterjee and Templin’s work suffers from a split personality.It was clearly written by two people with different styles, whoseem not to have been able to decide whether it was intended asa general review of pterosaurs and their literature or as a newcontribution to our understanding of pterosaur flight. The majorityof the book is a general review of pterosaurs that is rather mud-dled and often omits recent contributions. The authors suggestthat there is little agreement among pterosaur workers on eventhe smallest details; however, a general consensus on almost alltopics has been forged by pterosaur workers in a recent series ofworkshops and symposia, and while there are dissenters on mostsubjects, the extent of agreement is remarkable.

The book includes various inaccuracies and inconsistencies.For example, the term pterodactyl is used in a number of placesto refer to all pterodactyloids when it properly refers only to mem-bers of the genus Pterodactylus; pterosaurs are described as qua-drupedal knuckle walkers whereas knuckle walking properly re-fers to walking on flexed proximal interphalangeal joints of themanus and pterosaurs walked with their metacarpophalangealjoints hyperextended and the palmar surfaces of digits I-III incontact with the ground; Martill and Unwin’s (1989) interpretationof soft tissue preserved in association with a radius and ulna aswing membrane is accepted, while Kellner’s (1996) strident ar-guments that the soft tissue was body wall are not mentioned;and large pterodactyloids such as Pteranodon are described asfeeding by dipping fish while swimming (p. 56) and as probablyunable to take off from water (p. 53)—perhaps this explains thelarge numbers of Pteranodon specimens in the Niobrara Forma-tion.

The book also perpetuates some misinterpretations of ptero-saurs. The interpretation of pterosaur wing structure is presentedin terms of a birdlike versus batlike dichotomy, whereas it is nowclear that the pterosaur wing was as different from bird and batwings as bird and bat wings are from each other. Actinofibrils aredescribed as flattening the wing membrane to prevent billowing,whereas they were too slender to have resisted bending and in-stead redistributed tension and prevented chordwise narrowing ofthe membrane under load. The cranial crests of large pterodac-tyloids are described as primarily functioning as rudders for steer-ing, whereas although the large, laterally projected area of thecrest could have produced yaw forces, the significant intraspecificvariation in crest size—including their complete absence in im-mature individuals—the much greater yaw forces that could beproduced by controlled wing asymmetry, and the great variationin size, shape, and position of crests indicate that the primaryfunction was display.

The discussion of pterosaur flight goes beyond mere review

and presents a new analysis of the flight of 10 genera using mo-mentum streamtube theory based in large part on earlier work byTemplin (2000). Previous analyses have compared pterosaurs tofixed wing aircraft to estimate gliding performance or used vortexfield theory to model flapping wing performance, whereas mo-mentum streamtube theory compares the flapping wings of ptero-saurs to the actuator disk of helicopters. The authors suggest thatit is a reliable method because of the agreement of predicted andmeasured performance for some extant birds.

The work is interesting but suffers from two main problems:the data upon which the analysis was based (i.e., estimates ofmass, wingspan, and wing area) were not produced using a uni-form methodology, which makes the results of uncertain validity;and although the results of the analysis differ significantly fromprevious analyses, there is insufficient discussion of why that is.Mass estimates of six taxa were taken from works by Brower andHazlehurst; however, other estimates of mass for Rhamphorhyn-chus and Pterodactylus by them were ignored without explana-tion. In addition, the estimates of mass and span for Pteranodonultimately came from an earlier study that used a specimen withonly its humerus and femur complete enough to measure as itsexemplar and yet arrived at an estimate of span 11% larger thanthe largest known specimen from the Niobrara Formation. Massestimates for the four other taxa were based on measurement dataand a regression analysis of mass and measurements of the firstsix taxa. Estimates of wing area of two taxa were taken fromwork by Hazlehurst, whereas his similar estimates for five othertaxa were ignored without explanation, and wing areas for theother eight taxa were measured from reconstructed wing plan-forms that are not reproduced (except perhaps as tiny silhouettes)and so cannot be evaluated. As for the comparison of the resultsof this analysis and previous ones, Chatterjee and Templin’s anal-ysis suggests that pterosaurs had significantly better flight perfor-mance than previously thought, and it is suggested that the dif-ferences result from lower estimates of drag due to flatter camberand cleaner flow. However, there is no discussion of whethersome of the improved performance results from differences in thedata upon which the analyses were based or from using momen-tum streamtube theory, and there is no discussion of why theresults of this analysis are preferable to those of previous analy-ses.

Based on the improved flight performance and estimates ofcontinuously available power, the latter estimated on the assump-tions that muscle mass was directly proportional to body massand that muscle power output was equivalent to that of extantbirds, the authors suggest that there were three modes of pterosaurflight: hovering, continuous flapping, and soaring. While the firstassumption is probably not unreasonable, the second may not bebecause it is not clear that early pterosaurs were endothermic orthat their muscle physiology and aerobic capacity was equivalentto that of extant birds. Despite that, it is suggested that smallpterosaurs with wingspans of less than 1 m (e.g., Eudimorphodon,Dorygnathus, Rhamphorhynchus, and Pterodactylus) were capa-ble of continuous hovering flight, and fed by hovering just abovewater and dipping prey at its surface. However, the fact that smallpterosaurs might have been capable of continuous hovering flightshould not be taken as evidence that it was a major componentof their behavioral repertoire. The analysis suggests that all butthe very largest pterosaurs (e.g., 70 kg, 10.4 m Quetzalcoatlus)were capable of continuous flapping flight, quite different fromprevious works that suggested that large pterosaurs over perhaps5 m wingspan were incapable of continuous flapping. Chatterjeeand Templin acknowledge that large pterosaurs probably utilized

626 JOURNAL OF PALEONTOLOGY, V. 79, NO. 3, 2005

thermal and slope soaring to a considerable extent, and also sug-gest that Pteranodon and Quetzalcoatlus might also have utilizeddynamic soaring. Previous authors have concluded that Pterano-don could not fly fast enough to soar dynamically, but the im-proved performance predicted by this analysis would have per-mitted high speeds making dynamic soaring possible; however,given what we know of the ecology of Quetzalcoatlus, it is un-likely that it had access to the sustained winds that are necessaryfor dynamic soaring.

Buffetaut and Mazin’s Evolution and Palaeobiology of Ptero-saurs is an excellent symposium volume resulting from the verysuccessful 200 Years of Pterosaurs Symposium held in 2001 inToulouse to commemorate the bicentennial of Cuvier’s interpre-tation of Pterodactylus antiquus as a flying reptile. The volumeincludes 20 papers from 34 authors covering almost the entirebreadth of pterosaur research.

Discovery of new specimens and new taxa is continuing world-wide, and eight papers describe new finds. Wellnhofer describesa new specimen from the Triassic of Austria identified as Eudi-morphodon cf. ranzii that differs from other Eudimorphodonspecimens in that the ventral end of the coracoid is expandedanteroposteriorly and the corresponding articular facets on thesternum are borne on elongate processes. As a result the sterno-coracoid articulations would have prevented fore and aft rockingof the coracoid on the sternum, which seems to be an early so-lution to the problem of stabilizing the pectoral girdle that wassolved by the evolution of the rotated scapulae and scapulonotar-ial articulations in the advanced pectoral girdle of large pterodac-tyloids. Carpenter et al. describe an incomplete rostrum of a newscaphognathine, Harpactognathus, that is the first record from theAmericas and is two-and-one-half times larger than the knownScaphognathus. The specimen has a bony sagittal crest on itsrostrum, and so adds to the rapidly growing record of crestedrhamphorhynchoids. Buffetaut, Grigorescu, and Csiki describe anew giant azhdarchid, Hatzegopterus, from Romania based onhumeral and skull fragments with an estimated wingspan rivalingthat of Quetzalcoatlus and an estimated skull length of 2.7–2.9m, an almost inconceivable size in a flying animal. Pereda-Su-perbiola et al. describe Phosphatodraco, a new azhdarchid fromMorocco with an estimated wingspan of 5 m, based on an incom-plete cervical series, and Kellner and Moody describe an anhan-guerid scapulocoracoid from Venezuela. Frey, Martill, and Buchydescribe two new specimens from Brazil: Ludodactylus, an or-nithocheirid with a backward-directed crest like Pteranodon andabundantly toothed jaws that looks as though it could easily beancestral to Pteranodon; and a new Tapejara species with a tallsoft tissue crest that may have been four to five times as tall asthe bony skull proper. The same authors plus Tischlinger alsodescribe spectacular soft tissue preservation in new specimensfrom Solnhofen and the Santana Formation, including the nowfamous ‘dark wing’ specimen of Rhamphorhynchus that showsthe fine structure of the patagium with a network of blood vesselsand muscle or collagenous fibers lying perpendicular to actinofi-brils. Other specimens reveal traces of a rhamphotheca, clawsheathes, heel pads, and webbing between toes.

Six papers present reviews, new studies, and reinterpretationsof materials. Dalla Vecchia provides a thoughtful review of Tri-assic pterosaurs that includes new observations. He notes thatPeteinosaurus has trimorphodont dentition and Preondactylus hasserrate teeth that suggest it also had trimorphodont dentition, thusall Triassic pterosaurs seem to share it; all also seem to share thecompressed metatarsus that is also seen in Dimorphodon and An-urognathus; and Eudimorphodon and Preondactylus lack theelongate pre- and postzygapophyses and hemal arches that stiffenthe tail in many rhamphorhynchoids, and so may be primitive.However, Dalla Vecchia points out that our window into the world

of Triassic pterosaurs is very narrow, and we need more materialand better geographic and temporal coverage to clarify the earlyevolution of pterosaurs. Bonde and Christiansen describe an acid-transfer-prepared specimen of Rhamphorhynchus and documentfine details of vertebral and sternal pneumaticity. They note thatthere is no clear evidence of similar pneumatization in Triassicpterosaurs, so the pneumatization of the axial skeleton in ptero-saurs, sauropodomorphs, and theropods may be convergent. Steelreviews the surviving examples of the first thin sections of ptero-saur bones that were prepared in 1855, and Sayao looks at bonehistology of multiple different bones in two specimens from Bra-zil, documenting variation, and noting that the cessation of growthas the animal reached adult size was not simultaneous in all skel-etal elements. Bennett, in what must be most sincere flattery ofDilkes for his dissertation on Maiasaura, reconstructed the pec-toral myology of basal and derived pterosaurs to examine theevolution of the pectoral girdle of pterosaurs, and argues that thecomplexity of the advanced pectoral girdle of large pterodacty-loids is so great as to make convergent evolution in multiple lin-eages unlikely. The pectoral girdle is approached from anotherangle by Frey, Buchy, and Martill, who divide large pterodacty-loids into low wing (i.e., azhdarchoids) and high wing (i.e., or-nithocheiroids) groups on the basis of their girdle morphology.Based on comparisons to low and high wing airplanes, they sug-gest that the low wing configuration would have been more un-stable and resulted in a more maneuverable flight; however, inflapping cylindrically cambered pterosaur wings the position ofthe center of lift is not fixed relative to the center of gravity, andthe two pectoral girdle configurations may reflect musculoskeletalrather than aerodynamic selection.

An important focus of the symposium was the tracksite atCrayssac, and four papers examine pterosaur trackways. Mazin,Billon-Bruyat, Hantzpergue, and Lafaurie reviewed the Crayssactrackways, which provide a wonderful record of pterosaur loco-motion, though one produced on a quite incompetent substrateand as a result recording much kinematic information and oftenlacking anatomical detail. In a surprising and intriguing result,they show that the width between manus prints is directly cor-related with speed (i.e., the faster the wider), and the opposite ofwhat Bennett predicted. They also describe clear crocodiliantrackways from Crayssac that finally put to rest the notion thatany Pteraichnus trackways could have been made by crocodilians.Rodriguez-de la Rosa describes a new trackway locality from theCampanian of Mexico that is interpreted as a freshwater, lacus-trine environment, whereas heretofore trackways have been as-sociated with marine tidal environments. Lockley and Wright re-view swim tracks and feeding traces made by pterosaurs thatpresumably would have produced typical Pteraichnus trackwaysunder other conditions. The swim marks typically consist of fourclosely spaced scratches produced by the toes of an extended pesbarely contacting the substrate, and no manus scratch marks seemto be present, which suggests that the forelimb may not have beenused when swimming. Billon-Bruyat and Mazin throw caution tothe wind and stride boldly into the field of ichnotaxonomy, con-cluding that all presently known pterosaur footprints pertain to asingle ichnospecies, Pteraichnus saltwashensis, with a stratigraph-ic range from the Kimmeridgian through the Maastrichtian. Theydoubt that Purbeckopus is pterosaurian and note that Agadiri-chnus from the Moroccan Cretaceous may be a senior synonymof Pteraichnus; if so, it is to be hoped that Pteraichnus can beconserved so as to avoid unnecessary confusion.

In separate papers, Kellner and Unwin present cladistic anal-yses of the Pterosauria, which differ significantly in a number ofareas. There is uncertainty about the relationships of Triassic andEarly Jurassic pterosaurs and one major difference between the

627REVIEWS

two cladograms is in the placement of the anurognathids. Kell-ner’s analysis suggests that they are the sister group of all otherpterosaurs despite no fossil record before the Middle Jurassic,whereas Unwin’s places them further up the tree close to thecampylognathoidids. Another major difference between the twocladograms is in the relationships of the large pterodactyloids.Kellner’s analysis suggests that large pterodactyloids with ad-vanced pectoral girdles form a monophyletic Dsungaripteroidea,whereas Unwin’s analysis suggests parallel evolution of the ad-vanced pectoral girdle in two or three lineages as they increasedin size. Both analyses use more proportional characters (e.g., wingphalanx 1 longer than 2) than I am comfortable with, and bothauthors coined new names for many nodes, which seems unwisegiven the present state of flux of our understanding of pterosaurrelationships; however, their contrasting views show where morework is needed.

Both books include broad general coverage of the state ofknowledge of pterosaurs, but neither replaces Wellnhofer’s (1991)Illustrated Encyclopedia of Pterosaurs with its excellent coverageof pterosaurs and their fossil record and a thorough bibliography,now unfortunately out of print. Anyone wanting an excellent gen-eral review of pterosaurs should get Wellnhofer’s book first, andsupplement it with newer technical publications as needed. Buf-fetaut and Mazin’s volume is an essential addition to the library

of anyone interested in pterosaurs; it is a finger on the pulse ofpterosaur research that provides up-to-date, broad coverage ofpterosaur research since Wellnhofer’s book and an entree into thenewest technical literature. I cannot recommend Chatterjee andTemplin’s book as a general review of pterosaurs, but the flightanalysis is very intriguing and should be of interest to anyonefascinated by the flight of pterosaurs or other extinct animals.

REFERENCES

KELLNER, A. W. A. 1996. Reinterpretation of a remarkably well preservedpterosaur soft tissue from the Early Cretaceous of Brazil. Journal ofVertebrate Paleontology, 16:718–722.

MARTILL, D. M., AND D. M. UNWIN. 1989. Exceptionally well preservedpterosaur wing membrane from the Cretaceous of Brazil. Nature, 340:138–140.

TEMPLIN, R. J. 2000. The spectrum of animal flight: Insects to pterosaurs.Progress in Aerospace Sciences, 36:393–436.

WELLNHOFER, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Sal-amander Books, Ltd., London, 192 p.

S. CHRISTOPHER BENNETT

Department of Biological Sciences &Sternberg Museum of Natural History

Fort Hays State UniversityHays, Kansas 67601-4099