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BOLETIM DO MUSEU NACIONAL NOVA SÉRIE RIO DE JANEIRO - BRASIL ISSN 0080-3200 GEOLOGIA N o 73 20 DE OUTUBRO DE 2004 A NEW TELEOST FISH FROM THE EARLY CRETACEOUS OF NORTHEASTERN BRAZIL 1 (With 10 figures) FRANCISCO J. DE FIGUEIREDO 2 , 3 VALÉRIA GALLO 2 , 4 ABSTRACT: Beurlenichthys ouricuriensis gen. et sp.nov. is described on the basis of material from the Araripe and Sergipe-Alagoas basins. At first examination, the fish shows overall similarity to the marine teleost Santanichthys diasii from the lower Cretaceous of the Araripe Basin, Northeastern Brazil. However, the new taxon differs from S. diasii in many anatomical features, such as: presence of a dentigerous lamina on a large and curved maxilla; premaxilla bearing spaced teeth shaped like a rose thorn and possessing short and rounded ascending process; absence of skull roof fontanels and fenestrae; and first preural and first ural centra separated. Key words: Teleostei, new taxon, early Cretaceous, Northeastern Brazil. RESUMO: Um novo peixe teleósteo do Eocretáceo do nordeste do Brasil. Beurlenichthys ouricuriensis gen. et sp.nov. é descrito com base em material das bacias do Araripe e de Sergipe-Alagoas. À primeira vista, o peixe mostra similaridade geral com o teleósteo marinho Santanichthys diasii do Eocretáceo da Bacia do Araripe, nordeste do Brasil. Entretanto, o novo táxon difere de S. diasii com relação a vários caracteres anatômicos, tais como: presença de um grande e curvo maxilar com lâmina dentígera; pré-maxilar com processo ascendente curto e arredondado, portando dentes espaçados em forma de espinho de rosa; teto craniano carecendo de fontanelas e fenestras; e primeiro centro pré-ural e primeiro centro ural não fusionados. Palavras-chave: Teleostei, novo táxon, Cretáceo Inferior, nordeste do Brasil. INTRODUCTION SILVA SANTOS (1958) described Leptolepis diasii Silva Santos, 1958, a teleost fish from the Araripe Basin, based on three small-sized specimens preserved in carbonate concretions. He included this taxon in the widespread and poorly defined genus Leptolepis according to certain authors (e.g., SCHAEFFER, 1947) who in the past interpreted the morphology and systematics of various 1 Submitted on July 21, 2004. Accepted on October 13, 2004. 2 Universidade do Estado do Rio de Janeiro, Departamento de Zoologia. Rua São Francisco Xavier, 524, Maracanã, 20559-900, Rio de Janeiro, RJ, Brasil. 3 Museu Nacional/UFRJ, Programa de Pós-Graduação em Ciências Biológicas/Zoologia. Quinta da Boa Vista, São Cristóvão, 20940-040, Rio de Janeiro, RJ, Brasil. E-mail: [email protected]. 4 Fellow of the Programa de Incentivo à Produção Científica, Técnica e Artística (PROCIÊNCIA-UERJ) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

Transcript of BOLETIM DO MUSEU NACIONAL - labictio.uerj.br boletim do museu nacional nova sÉrie rio de janeiro -...

Page 1: BOLETIM DO MUSEU NACIONAL - labictio.uerj.br boletim do museu nacional nova sÉrie rio de janeiro - brasil issn 0080-3200 geologia no 73 20 de outubro de 2004 a new teleost fish from

BOLETIM DO MUSEU NACIONAL NOVA SÉRIE

RIO DE JANEIRO - BRASIL

ISSN 0080-3200

GEOLOGIA No 73 20 DE OUTUBRO DE 2004

A NEW TELEOST FISH FROM THE EARLY CRETACEOUS OF NORTHEASTERN BRAZIL 1

(With 10 figures)

FRANCISCO J. DE FIGUEIREDO 2, 3 VALÉRIA GALLO 2, 4

ABSTRACT: Beurlenichthys ouricuriensis gen. et sp.nov. is described on the basis of material from the Araripe and Sergipe-Alagoas basins. At first examination, the fish shows overall similarity to the marine teleost Santanichthys diasii from the lower Cretaceous of the Araripe Basin, Northeastern Brazil. However, the new taxon differs from S. diasii in many anatomical features, such as: presence of a dentigerous lamina on a large and curved maxilla; premaxilla bearing spaced teeth shaped like a rose thorn and possessing short and rounded ascending process; absence of skull roof fontanels and fenestrae; and first preural and first ural centra separated.

Key words: Teleostei, new taxon, early Cretaceous, Northeastern Brazil. RESUMO: Um novo peixe teleósteo do Eocretáceo do nordeste do Brasil.

Beurlenichthys ouricuriensis gen. et sp.nov. é descrito com base em material das bacias do Araripe e de Sergipe-Alagoas. À primeira vista, o peixe mostra similaridade geral com o teleósteo marinho Santanichthys diasii do Eocretáceo da Bacia do Araripe, nordeste do Brasil. Entretanto, o novo táxon difere de S. diasii com relação a vários caracteres anatômicos, tais como: presença de um grande e curvo maxilar com lâmina dentígera; pré-maxilar com processo ascendente curto e arredondado, portando dentes espaçados em forma de espinho de rosa; teto craniano carecendo de fontanelas e fenestras; e primeiro centro pré-ural e primeiro centro ural não fusionados.

Palavras-chave: Teleostei, novo táxon, Cretáceo Inferior, nordeste do Brasil.

INTRODUCTION SILVA SANTOS (1958) described Leptolepis diasii Silva Santos, 1958, a teleost fish from the Araripe Basin, based on three small-sized specimens preserved in carbonate concretions. He included this taxon in the widespread and poorly defined genus Leptolepis according to certain authors (e.g., SCHAEFFER, 1947) who in the past interpreted the morphology and systematics of various 1 Submitted on July 21, 2004. Accepted on October 13, 2004. 2 Universidade do Estado do Rio de Janeiro, Departamento de Zoologia. Rua São Francisco Xavier, 524, Maracanã,

20559-900, Rio de Janeiro, RJ, Brasil. 3 Museu Nacional/UFRJ, Programa de Pós-Graduação em Ciências Biológicas/Zoologia. Quinta da Boa Vista, São Cristóvão,

20940-040, Rio de Janeiro, RJ, Brasil. E-mail: [email protected]. 4 Fellow of the Programa de Incentivo à Produção Científica, Técnica e Artística (PROCIÊNCIA-UERJ) and Conselho

Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

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superficially similar taxa differently.

MAISEY (1991) described and illustrated an incomplete caudal skeleton assigned to “Leptolepis” diasii. He briefly discussed its systematic position and considered the species as an Euteleostei incertae sedis.

SILVA SANTOS (1991a) erected the genus Santanichthys as a replacement genus for “Leptolepis” diasii and proposed a very different restoration of the caudal skeleton provided by MAISEY (1991). Afterwards, SILVA SANTOS (1991b; 1995) reviewed Santanichthys (=Leptolepis) diasii using new material. He described in some detail the cranial and post-cranial elements of the fish and indicated the caudal skeleton, illustrated by him in 1991b (p.31, fig.10), as belonging to a new taxon, thus excluding the specimen of the type series. The caudal skeleton of Santanichthys was only described but not illustrated in the 1995' paper. MAISEY (1993, p.9, fig.6) agreed with the status of Santanichthys and assigned the caudal skeleton of AMNH 12780 to the taxon.

The paleontologist Rubens da Silva Santos mechanically prepared the anterior part of the specimen used to show the caudal skeleton in his paper of 1991, but unfortunately he passed away without formally describing it. Only a few notes remain.

While studying the material used in the review of Santanichthys provided by SILVA SANTOS (1995), we distinguished the fish as a new taxon, very similar to Santanichthys. In addition, we included one additional specimen from the Sergipe-Alagoas Basin (MASSA et al., 2001). This taxon, Beurlenichthys ouricuriensis gen. et sp.nov., is described and its taxonomic position is discussed below.

MATERIAL AND METHODS The material belongs to the paleontological collections of the Departamento Nacional de Produção Mineral and of the Departamento de Zoologia of the Universidade do Estado do Rio de Janeiro. It is referred herein, respectively, under the abbreviations DGM and Pz.DBAV.UERJ, followed by the register number. We mechanically prepared the specimens using steel needles of different sizes. The specimens were dusted with ammonium chloride to enhance contrast and they were drawn using a Nikon SMZ 800 stereomicroscope with camera lucida.

Except for Brazilian taxa [Clupavus brasiliensis Silva Santos, 1985; Santanichthys diasii (Silva Santos, 1958), and Scombroclupeoides scutata (Woodward, 1908)], the other leptolepid-like fishes used for comparison are based on the literature data. The taxa are the following: Cavenderichthys talbragarensis (Woodward, 1895); Leptolepis coryphaenoides (Bronn, 1830); Leptolepides sprattiformis (Blainville, 1818); Luisichthys vinalesensis White, 1941; Orthogonikleithrus leichi Arratia, 1987; Paraclupavus caheni de Saint-Seine & Casier, 1962; Longileptolepis wiedenrothi (Arratia & Thies, 2001); Proleptolepis elongata Nybelin, 1974; and Tchernovichthys exspectatum Gayet, 1994.

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ANATOMICAL ABBREVIATIONS

We use “r” and “l” after abbreviations of anatomical structures to indicate right and left side respectively. (ACH) anterior ceratohyal; (AA) angulo-articular; (a.pr.) anterior process; (a.pr.vo.) anterior process of vomer; (ASPH) autosphenotic; (be.f.) beryciform foramen; (BBP) basibranchial; (BR) branchiostegal rays; (CL) cleithrum; (CO) coracoid; (D) dentary; (DHY) dorsal hypohyal; (DSPH) dermosphenotic; (ep.b.) epiphysean branch; (EP) epural; (EPN) epineural; (EPP) epipleural; (EXC) extrascapula; (f.r.) fin rays; (FR) frontal; (GH) glossohyal; (HM) hyomandibula; (H) hypural; (IO) infraorbital; (iorb.s.c.) infraorbital sensory canal; (LA) lachrymal; (ll.c.) lateral line sensory canal; (m.pr.) medial articular process; (md.s.c.) mandibular sensory canal; (MES) mesethmoid; (mpl) middle pit-line; (MPT) metapterygoid; (MX) maxilla; (NA) nasal; (NS) neural spine; (nsPU1) neural spine of the first preural centrum; (OP) opercle; (op.pr.HM) opercular process of the hyomandibula; (PA) parietal; (pa.b.) parietal branch; (PAL) palatine; (PCL) postcleithrum; (PELV) pelvic bone; (PH) parhypural; (PMX) premaxilla; (POP) preopercle; (pop.s.c.) preopercular sensory canal; (PS) parasphenoid; (PT) posttemporal; (PTO) pterotic; (PTS) pterosphenoid; (PU) preural centrum; (Q) quadrate; (RA) radial; (RAR) retroarticular; (S) sympletic; (SCL) supracleithrum; (SMX) supramaxilla; (SORB) supraorbital; (sorb.s.c.) supraorbital sensory canal; (st.co.) supratemporal commissure; (tmp.c.) temporal canal; (U) ural centrum; (UN) uroneural; (VHY) ventral hypohyal.

MEASUREMENTS (all expressed in mm)

(AFBL) anal fin base length – the longitudinal measurement along the region where the anal fin articulates with the body; (BD) body depth – the greatest dimension measured from the dorsalmost to the ventralmost point of the body contour; (CPD) caudal peduncle depth – the shallowest depth of the peduncle; (CPL) caudal peduncle length – oblique distance between the posterior end of the base of the anal fin to the posteriormost end of the mostly extending hypural; (DFBL) dorsal fin base length – the longitudinal measurement along the region where the dorsal fin articulates with the body; (HD) head depth – distance taken from the midline at the occiput vertically downward to the ventral contour of the head; (HL) head length – distance between the anteriormost point of the head to the posteriormost extent of the opercle; (PAL) preanal length – measured from the anteriormost tip of the head to the anterior end of the base of the anal fin; (PDL) predorsal length – distance from the tip of the head to the base of the anteriormost dorsal fin ray; (PPL) prepectoral length – measured from the anteriormost tip of the head to the anterior end of the base of the pectoral fin; (PVL) prepelvic length – measured from the anteriormost tip of the head to the anterior end of the base of the pelvic fin; (SL) standard length – distance from the anteriormost point of the head to the posteriormost extent of the hypurals; (TL) total length – distance between the most anteriorly projecting part of the head and the posteriormost point of the caudal fin.

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SYSTEMATIC PALEONTOLOGY

Subdivision: Teleostei Cohort: Clupeocephala incertae sedis

Beurlenichthys gen.nov. Etymology – Beurlenichthys, in honor to the paleontologist Karl Theodor Beurlen, who collected the type-specimen; ichthys - from the Greek word, fish.

Type and only known Species – Beurlenichthys ouricuriensis, sp.nov.

Stratigraphy – Lower Cretaceous (Albian-Aptian); Romualdo Member (Santana Formation, Araripe Basin) and Taquari Member (Riachuelo Formation, Sergipe-Alagoas Basin).

Diagnosis – Small fish reaching about 60mm total length; medioparietal skull; skull roof lacking fontanels and fenestrae; parietal branch of the supraorbital sensory canal piercing the parietal; premaxilla with spaced teeth shaped like a rose thorn and a rounded ascending process; maxilla elongate and arched bearing a dentigerous lamina on the oral border; two large and smooth supramaxillae; dentary with rudimentary teeth near symphysis; quadrate-mandibular articulation located in the posterior third of the orbit; hyomandibula lacking preopercular process; preopercle with three simple tubules of the preopercular sensory canal not reaching its posteroventral margin; anterior ceratohyal with large triangular beryciform foramen; epineural intermuscular bones present but not extending onto the caudal region; caudal endoskeleton with two uroneurals, the first one totally covering the dorsal margin of the first preural centrum and the second one, lanceolate, reaching the posterior end of the second ural centrum; hemal spines fused with the centra anterior to the second preural centrum; first ural centrum fused to the second hypural; first preural centrum with a leaf-like neural spine.

Beurlenichthys ouricuriensis sp.nov. (Figs.1-10)

1991a - Santanichthys diasii Silva Santos: 433 (nomen nudum) 1991b - Santanichthys diasii Silva Santos: 30, fig.10 (nomen nudum) 1995 - Santanichthys diasii Silva Santos: 250, pl.I, figs.1-2; text-fig.1

Holotype – DGM 683-P, nearly complete specimen composed of part and counterpart, preserved in a carbonate concretion (Fig.1).

Paratype – Pz.DBAV.UERJ 107, small and complete fish, Riachuelo Formation, Municipality of Rosário do Catete, State of Sergipe.

Diagnosis – As for genus.

Morphometric parameters (mm) – SL, 53 and 45; TL, 60 and 52; BD, 11.2 and 8; HL, 14 and 11; HD, 10.5 and 8; PPL, 16 and 14.5; PVL, 30 and 28; PDL, 26.5 and 20; PAL, 44 and 40; CPL, 8.8 and 6; CPD, 6.7 and 5.5; DFBL, 4.7 and 4.2; AFBL, 3.6 and 4. The first values refer to the holotype.

Etymology – Named after Ouricuri, the county where the type-locality is found.

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Type-locality – Casa de Pedra, Municipality of Ouricuri, Southern Chapada do Araripe, State of Pernambuco, NE Brazil.

DESCRIPTION GENERAL FEATURES

Beurlenichthys ouricuriensis is a small and slender fish (Fig.1). The body appears to be compressed since all specimens are preserved laterally on the rock. The specimen from the Riachuelo Formation shows a marked torsion in the trunk while that from the Santana Formation is little deformed. The head is longer than deep. The head length is 25% of total length and 75% of body depth at the level of the dorsal fin. The orbit length is about 30% of head length. The dorsal fin is short based and originates at the mid-point of the back. The anal fin is apparently short based and backwardly positioned on the body. The pelvic fin originates a little behind the vertical line of the origin of the dorsal fin. The caudal fin is homocercal and deeply forked. SKULL

The skull roof is smooth and lacks fontanels and fenestrae.

The mesethmoid (Fig.2, MES) is partially preserved in both specimens, but it is best seen in Pz.DBAV.UERJ 107. It is a short bone with a long and arched postero-lateral process. Dorsoposteriorly, the bone bifurcates producing two long and slender processes extending to each frontal. Anteriorly, there is a deep lateral fossa to receive the anterior end of premaxilla and maxilla. The anterodorsal end of the mesethmoid is prominent. There is no evidence of an ethmoidal commissure. Laterally, the mesethmoid meets the long and slender nasal (Fig.2, NA). Anteroventrally, the mesethmoid contacts the dilated and rounded anterior process of vomer (Figs.2-3, a.pr.vo.). The toothless vomer possesses a flat and short process which extends backwards to contact the parasphenoid.

The lateral ethmoid is too badly preserved to allow an accurate description but it seems to be a flimsy laminate bone contributing to the anterior limit of the orbit.

The frontal (Figs.2-3, FR) is elongate, anteriorly narrow and laterally expanded rear. The supraorbital sensory canal (Figs.2-3, sorb.s.c.) runs in a conspicuous tubular ridge on the outer surface of the bone. In the posterior half of the frontal, there are two branches detaching from the principal canal. The medial branch is the short epiphysean branch (Fig.2, ep.b.). The other is the long parietal branch (Fig.2, pa.b.) that runs posterodorsally on the bone, reaching and piercing part of the parietal. In the posterior limit of the orbit, the frontal laterally produces a wing-like process bearing a delicate bone ridge which is directed towards the supraorbital sensory canal, as in Leptolepis normandica Nybelin, 1974 (see NYBELIN, 1974, p.10, text-fig.1).

The parietal (Fig.2, PA) is large and squarish. It corresponds to about of one-third of the frontal length. Each parietal meets its antimere in the mid-line exhibiting a medioparietal condition. There is a middle pit-line (Fig.2, mpl) incised in the bone.

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Fig.1- Holotype of Beurlenichthys ouricuriensis gen. et sp.nov. (DGM 683-P). (A) part; (B) counterpart. Scale bar = 2cm.

B

A

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The pterotic (Figs.2-3, PTO) is a large trapezoidal bone. It carries the temporal canal (Fig.2, tmp.c.) near the lateral border. Laterally, the pterotic possesses a shallow articular facet for the hyomandibula.

The autosphenotic (Figs.2-3, ASPH) is a large triangular bone placed at the dorso-posterior limit of the orbit. Dorsally, it is covered by the wing-like lateral process of the frontal and dermosphenotic.

The pterosphenoid (Fig.2, PTS), best seen in Pz.DBAV.UERJ 107, is a large trapezoidal bone with a straight anterior border which contacts the orbitosphenoid (not preserved). Ventrally, it meets the oblique dorsal border of the belophragma which is the only part of the basisphenoid that was preserved. The pterosphenoid seems to compose with the orbitosphenoid and basisphenoid a well-ossified interorbital septum.

The parasphenoid (Fig.2, PS) is a long and narrow bone. It produces a shallow median keel along the orbit region. Ventrally, the bone tapers backwards covering completely the basioccipital whose outline is only observed in the Pz.DBAV.UERJ 107. There is a moderate and upright ascending process. Teeth are lacking.

The extrascapula (Fig.3, EXC) is a laminate elliptical bone, wider than long, located posteriorly to the pterotic. It is longitudinally crossed by the beginning of the lateral line sensory canal (Fig.3, ll.c.) and transversally by the supratemporal commissure (Fig.3, st.co.). CIRCUMORBITAL SERIES

The supraorbital (Fig.2, SORB) is a long fusiform bone lying laterally to the frontal above the orbit. A posterior supraorbital bone (common to species of Leptolepis, see WENZ, 1967) is lacking.

The lachrymal (Fig.3, LA) is a large trapezoidal bone and the second infraorbital (Fig.3, IO2) is moderately long and slender. The infraorbital sensory canal (Fig.3, iorb.s.c.) runs along the median line of the bones. No tubules are observed on their surface. There are remnants of posterior infraorbitals (Fig.2, IO) whose number and shape are not possible to determine.

The dermosphenotic (Fig.2, DSPH) is a large squarish bone bearing three diverging tubules of the infraorbital sensory canal. The anterior tubule is obliquely curved towards the wing-like process of the frontal and ends blindly without reaching the supraorbital sensory canal. The posterior tubule crosses the bone towards the temporal canal onto the pterotic bone. The ventral tubule appears to be very reduced.

The region occupied by the sclerotic ring is damaged. Only fragments are preserved not allowing a satisfactory description. OPERCULAR SERIES

The preopercle (Fig.3, POP) is narrow and boomerang-shaped. Both preopercular limbs are long and approximately equal in length. The dorsal limb is vertically oriented and reaches the opercular process of the hyomandibula. The preopercular sensory canal (Fig.3, pop.s.c.) is enclosed in a large bony tube running close to the anterior border of the bone. It gives off three simple tubules on the horizontal limb; these do not reach the posteroventral margin of the bone.

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Fig.2- Head of Beurlenichthys ouricuriensis gen. et sp.nov. in lateral view (DGM 683-P, part). (A) photograph; (B) line drawing. Scale bar = 0.4cm.

A

B

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The opercle (Fig.3, OP) is a trapezoid bone with a strengthened anterior border. Most of the bone is damaged in examined specimens but it appears to possess a rounded postero-dorsal border. Ventrally, it meets the subopercle in an oblique contact zone.

The subopercle is poorly preserved in the examined specimens and it appears to be approximately one-third of the opercle depth. It bears a short anterior process and shows a slightly round postero-ventral margin.

There are only remnants of what could be an interopercle. It seems to be a triangular and long bone hidden by the ventral limb of the preopercle. UPPER JAW

The premaxilla (Figs.3-4, PMX) is a subtriangular and elongate bone, best seen in Pz.DBAV.UERJ 107 (Fig.4). Its depth is about one-third of the length. Antero-dorsally, the bone possesses a short and rounded ascending process. The oral border carries a single row of few spaced rose-thorn shaped teeth.

The maxilla (Figs.2-3, MX) is a long and arched bone bearing a dentigerous lamina on the oral border. It extends backwards finishing at the level of the quadrate-mandibular joint. Its anterior process is curved and finishes in a simple reduced head.

There are two large and smooth supramaxillae (Fig.3, SMX) lying on the dorsal border of the maxilla. The anterior supramaxilla is a long fusiform bone whereas the posterior one is a large drop-like bone. The antero-dorsal process of the latter covers the postero-dorsal border of the anterior supramaxilla. Both bones lack ornamentation except for a longitudinal ridge on the posterior supramaxilla. LOWER JAW

The lower jaw is deep, twice as long as high with a well-developed coronoid process. The quadrate-mandibular joint is located in the posterior third of the orbit.

The dentary (Figs.2-3, D) forms most of the lower jaw. The symphysis is relatively deep and strongly inturned. Leptolepid notch and slime canal are absent. There is a set of a few minute teeth near symphysis. The mandibular sensory canal (Fig.3, md.s.c.) is well-developed and runs in a straight tube along the bone near its ventral margin.

The posterior third of the lower jaw is formed by the angulo-articular (Figs.2-3, AA). It is incomplete or hidden by other bones in the specimens examined. It bears a shallow and short articular facet for the quadrate. No pore for a sensory canal is visible. On the medial surface, the dentary overlaps the angulo-articular, so forming a very shallow Meckelian fossa.

The retroarticular (Figs.2-3, RAR) is a very reduced triangular bone placed on the postero-ventral corner of the lower jaw. It is apparently excluded from the articular facet for the quadrate.

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Fig.3- Head of Beurlenichthys ouricuriensis gen. et sp.nov. in lateral view (DGM 683-P, counterpart). (A) photograph; (B) line drawing. Scale bar = 0.4cm.

A

B

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Fig.4- Premaxilla of Beurlenichthys ouricuriensis gen. et sp.nov. as preserved in Pz.DBAV. UERJ 107. Scale bar = 0.1cm. HYOPALATINE SERIES

The hyomandibula (Figs.2-3, HM) shows an expanded and oblique dorsal articular facet. The upper half of the bone is very large and produces an anterior laminar outgrowth that lies on the metapterygoid. The hyomandibular branch of the facialis nerve exits through a reduced foramen placed at the middle point of the upper third of the hyomandibula. The opercular process (Fig.2, op.pr.HM) is short and stout, and it is placed in the upper third of the bone. The vertical arm of the hyomandibula is straight and long and lacks preopercular process.

The region occupied by the metapterygoid, ectopterygoid, and endopterygoid is very damaged in all specimens. The metapterygoid (Fig.3, MPT) is broken but it seems to be a squarish plate whereas ecto and endopterygoid are poorly preserved and do not allow a suitable description.

A subrectangular fragment of bone underlying the maxilla in DGM 683-P is interpreted here as a palatine (Fig.2, PAL). It bears a median dorsal ridge and lacks teeth. A similar feature is found in Ornategulum sardinioides (see FOREY, 1973, p.1307, fig.3).

The quadrate (Figs.2-3, Q) is a large triangular bone and inclined forwards. The postero-ventral process is elongate and acuminate. There is a deep notch to lodge the long and narrow sympletic (Figs.2-3, S). Antero-ventrally, the quadrate produces a moderate articular condyle. HYOID ARCH

The anterior ceratohyal (Fig.2, ACH) is a large hour-glass shaped bone; the dorsal border is straight and the ventral concave. It is twice as long as deep. There is a very large triangular beryciform foramen (Fig.2, be.f.) but not a groove for the hyoidean artery. Only the proximal end of three slender branchiostegal rays (Fig.2, BBR) is preserved in DGM 683-P. The posterior ceratohyal is not preserved.

The dorsal hypohyal (Fig.2, DHY) is badly preserved. It appears to be a reduced and nodular chondroid bone. The ventral hypohyal (Fig.2, VHY) is deeper than long and

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shows a smooth anterior articular margin for its antimere. The hypohyals articulate with the anterior ceratohyal probably by synchondrosis. BRANCHIAL ARCHES

Sited below the parasphenoid there is a long plate bearing viliform teeth on its dorsal surface. It is interpreted as the dermal portion of a basibranchial bone (Fig.2, BBP). Anteriorly, the basibranchial meets a curved and short bone that seems to be the glossohyal plate (Fig.2, GH). PECTORAL GIRDLE AND FIN

The posttemporal (Fig.5, PT) is a large laminate bone with an apparently well developed dorsal arm. The dorsal profile of the bone shows a slightly convex outline. The lateral line canal is almost straight and placed near the ventral portion of the bone.

The supracleithrum (Fig.5, SCL) is a large and spatulate bone and lies on the dorsal sharp process of the cleithrum. The lateral line canal (Fig.5, ll.c.) runs obliquely in this bone in its upper half. The cleithrum (Fig.5, CL) is a large and smooth bone with dorsal and ventral limbs of almost equal size; the latter is a little larger than the former. A large ridge strengthens most of the anterior border of the bone. The cleithrum broadens anteroventrally. The outer laminar surface is expanded posteriorly; the anteromedial lamina is absent. No cleithral organ is present.

Remnants of two postcleithra (Fig.5, PCL) are present. The dorsal one is a lunate and narrow laminar bone. The ventral one has a large proximal extremity and long and sharp posteroventral process.

The scapula is a reduced squarish bone meeting ventrally the large and anvil-shaped coracoid (Fig.5, CO). Two rod-like proximal radials and one nodular distal radial are preserved in Pz.DBAV.UERJ 107 (Fig.5, RA). The pectoral fin is composed of at least 14 rays. PELVIC GIRDLE AND FIN

The pelvic bone (Fig.6, PELV) is triangular and elongate possessing a strong medial articular process (Fig.6, m.pr.) and a long anterior process (Fig.6, a.pr.) with a shallow dorsal crest. The anterior end of the pelvic bone is opposite to the origin of the dorsal fin. Pelvic splint or axillary process are not visible. At least two proximal radials are visible. The pelvic fin is composed of at least seven segmented and distally branched rays. VERTEBRAL COLUMN AND MEDIAN FINS

There are 38 vertebrae, not including the ural centra, 28 are abdominal. The centra are well-ossified spool-shaped bones. The autocentrum (fused to arcocentra) is a thin and smooth layer in most of the vertebral column. It covers the chordacentrum that is apparently thick. Only the first preural and the first ural centra show deep grooves and longitudinal lateral ridges. The centra are as long as deep in the abdominal region, becoming gradually longer than deep in the caudal

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region. Neural and hemal arches are apparently fused with centra, except for the last preural centra. Neural and hemal spines are thin, short, and slightly inclined. There are, at least, three elongate, slender, and crescent-shaped supraneurals above the anterior vertebrae. The number of supraneurals is probably higher because the predorsal region is occupied by those bones together with many fragments of epineural intermuscular bones and neural spines so that separate elements cannot be recognized.

Fig.5- Pectoral girdle of Beurlenichthys ouricuriensis gen. et sp.nov. as preserved in Pz.DBAV. UERJ 107. Scale bar = 0.4cm.

The epineural intermuscular bones (Fig.7, EPN) are thin, long, and straight being fused to base of the neural arches. They extend all along the vertebral column not reaching the caudal region. The epipleural intermuscular bones

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(Fig.5, EPP) are visible only in the transition of the abdominal to the caudal regions. They are very thin, short, and straight.

The dorsal fin originates at the level of the eleventh to twelfth vertebrae and is composed of one rudimentary ray and 11 segmented and distally branched rays supported by 11 pterygiophores. The first pterygiophore is a large bifid bone whereas the others are slender and lanceolate.

The anal fin originates at the level of the 27 to 28 vertebrae. We count at least eight rays and corresponding pterygiophores.

Fig.6- Pelvic girdle of Beurlenichthys ouricuriensis gen. et sp.nov. as preserved in Pz.DBAV. UERJ 107. Arrow points anteriorly. Scale bar = 0.1cm.

CAUDAL ENDOSKELETON AND FIN

The caudal skeleton is well-preserved in all specimens. Figure 8 illustrates a caudal fin of a juvenile specimen. The hemal arches of the first and second preural centra (Figs.8-9, PU) and second ural centrum (Figs.8-9, U) are autogenous. The parhypural (Figs.8-9, PH) is elongate, slender, and broad at the proximal end. It is not fused to the first preural centrum. There are six hypurals (Figs.8-9, H). The first hypural is the largest. It possesses a reduced anterior finger-shaped process near its base and lies on a notch at the posterior border of the proximal end of the parhypural. The second hypural is slender and fused to the first ural centrum. The third hypural is broad and possesses a longitudinal marked ridge; it meets the second ural centrum. The remaining three hypurals gradually diminish in size upwards. There are two uroneurals (Fig.9, UN). The first totally covers the dorsal margin of the first preural centrum. The second lanceolate uroneural reaches the posterior end of the second ural centrum. There is no pleurostyle or stegural. Two long and curved epurals (Fig.9, EP) are preserved. The neural spines of the second and third preural centra are both equally elongated. The first preural centrum bears a leaf-like neural spine (Fig.9, nsPU1).

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A long and fusiform caudal scute is observed above and below the caudal peduncle.

There are 19 principal fin rays, nine are segmented and distally branched in the upper lobe and eight lie in the lower lobe. There are at least six procurrent rays (the two posteriormost are segmented) in the upper lobe and at least five in the lower lobe.

Fig.7- Restoration of vertebrae of the abdominal region of Beurlenichthys ouricuriensis gen. et sp.nov.; fig.8- caudal endoskeleton and fin rays of a juvenile of Beurlenichthys ouricuriensis gen. et sp.nov. Scale bar = 0.7cm.

7

8

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SQUAMATION

The trunk is covered with large, very thin, and round cycloid scales. They seem to be deeply imbricated. Each scale shows several concentric circuli on its surface but radii are absent. Scales are lacking on the head and fins.

Fig.9- Restoration of the caudal skeleton of Beurlenichthys ouricuriensis gen. et sp.nov. Scale bar = 0.2cm.

DISCUSSION AND CONCLUSIONS Taxonomic Validity of Beurlenichthys ouricuriensis

Beurlenichthys ouricuriensis has a number of diagnostic features that allows the proposition of a new genus and species. Among them is: 1) peculiar spaced rose-thorn shaped teeth on the premaxilla, 2) skull roof lacking fontanels and fenestrae, 3) dentary with few minute conical teeth near symphysis, 4) hyomandibula lacking preopercular process, 5) preopercle with three simple tubules of the preopercular sensory canal not reaching its posteroventral margin, 6) caudal endoskeleton with two uroneurals, 7) hemal arches of the first and second preural centra and second ural centrum are autogenous, and 8) first ural centrum fused to the second hypural.

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Fig.10- Restoration of the caudal skeleton of Santanichthys diasii based on DGM 687-P. Scale bar = 0.2cm.

Beurlenichthys and other leptolepid-like fishes

Due to the overall similarity between Beurlenichthys ouricuriensis and other leptolepid-like fishes a comparison with certain taxa is provided below.

Proleptolepis Nybelin, 1974 is known from the early Jurassic of Europe and Chile (ARRATIA & THIES, 2001; TAVERNE, 2001). The best known species is P. elongata (NYBELIN, 1974; PATTERSON, 1975; TAVERNE, 2001). Proleptolepis exhibits a triangular premaxilla lacking a defined ascendent process and possesses long preopercular limbs as it does in Beurlenichthys. Otherwise, Proleptolepis differs obviously from Beurlenichthys in various plesiomorphic features such as: (1) leptolepid notch present; (2) suborbital bone present; (3) notch at the posterior border of the preopercle; (4) preopercular sensory canal producing numerous long tubules; (5) higher number of hypurals (about 11) and uroneurals (about six); and (6) numerous fringing fulcra on the upper and lower lobes of the caudal fin.

Longileptolepis wiedenrothi was described from the early Jurassic of Germany (see ARRATIA, 2003). It is clearly distinct from B. ouricuriensis by the presence of: (1)

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some skull bones covered with a thin layer of ganoine; (2) an unusual premaxilla; (3) two suborbitals; (4) preopercular sensory canal with numerous tubules; (5) opercle with crenulate posterior border; (6) higher number of vertebrae (over 44); (7) first preural centrum with elongate neural spine; (8) at least five narrow and elongate uroneurals (see ARRATIA & THIES, 2001; ARRATIA, 2003).

The most recent definition of the family Leptolepidae is that of NYBELIN (1974). Leptolepis is currently represented only by two species: Leptolepis coryphaenoides and L. normandica. They are very similar in a first impression but a closer examination shows remarkable differences. The two taxa came from different lower Jurassic European localities (ARRATIA & THIES, 2001). Beurlenichthys ouricuriensis shares various plesiomorphies with Leptolepis coryphaenoides such as the absence of a connection between supraorbital and otic sensory canals and the presence of pit-line in the parietal. By contrast, L. coryphaenoides differs from B. ouricuriensis in the following features: (1) presence of 17-22 tubules exiting from the preopercular sensory canal (see WENZ, 1967); (2) hyomandibula bearing a well developed preopercular process; (4) two neural arches on the first ural centrum; (5) seven uroneurals (see PATTERSON & ROSEN, 1977); (6) first uroneural extending to the second preural centrum; (7) nine hypurals.

Luisichthys vinalesensis is a large fusiform fish known from the late Jurassic of Cuba included by ARRATIA (1997) into the Varasichthyidae. A higher number of hypurals (10) readly separates L. vinalesensis from B. ouricuriensis. However, in both taxa there is a fusion between the second hypural and the first ural centrum. Although this feature had been considered by ARRATIA (1997) as uniquely derived in L. vinalesensis, it is also found in Clupeomorpha.

Tchernovichthys exspectatum is a leptolepid-like fish described from the early Cretaceous of Israel as a Clupeocephala with close affinities with Clupeomorpha. GAYET (1994) pointed out that this taxon represents the oldest continental teleost known in the Middle East and it seems to be more closely related to Scombroclupeoides scutata from the early Cretaceous of Brazil. It shares with B. ouricuriensis a combination of primitive and derived features: (1) medioparietal skull; (2) two supramaxillae; (3) anterior ceratohyal largely perforated; (4) retroarticular excluded from the articular facet for the quadrate; (5) preopercular process lacking; (6) epineural and epipleural intermuscular bones; (7) dorsal and ventral caudal scutes. On the other hand, some characters allow separation of them. T. exspectatum possesses an untoothed dentary with the leptolepid notch, caudal fin with all centra free (first ural centrum fused to the second hypural in B. ouricuriensis), and higher number of uroneurals (three in T. exspectatum versus two in B. ouricuriensis).

Cavenderichthys talbragarensis occurs in the late Jurassic of Australia and its morphology has been studied by various authors (e.g., CAVENDER, 1970; NYBELIN, 1974; PATTERSON & ROSEN, 1977; ARRATIA, 1997). This taxon shares with B. ouricuriensis the presence of a short pit-line on the parietal; absence of a leptolepid notch and preopercular process; a preopercular sensory canal with few tubules; anterior ceratohyal fenestrated; and first preural centrum bearing a short neural spine. But C. talbragarensis can be distinguished from B. ouricuriensis by the absence of epipleurals; a higher number of vertebrae (43-45), hypurals (eight or nine), and uroneurals (seven); a remarkable reduction of the first preural centrum;

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the presence of a membranous outgrowth of the uroneural (stegural); and fringing fulcra on the upper lobe of the caudal fin.

Beurlenichthys ouricuriensis shares with Paraclupavus caheni, from the middle Jurassic of the Democratic Republic of Congo, the following features: (1) absence of suborbital; (2) presence of a single supraorbital; (3) oral border of the maxilla bearing a dentigerous lamina; (4) absence of a preopercular process; (5) few short tubules of the preopercular sensory canal not reaching the posteroventral border of the preopercle; and (6) supratemporal commissure without tubules. However, B. ouricuriensis is distinct from Paraclupavus caheni in showing: (1) two hypohyals; (2) fewer number of hypurals and uroneurals; (3) the first uroneural lying only on the first preural centrum; (4) second hypural fused to the first ural centrum; (5) first and second preural centra with autogenous hemal arches; (6) two first hypurals not fused proximally.

Regarding Cretaceous Brazilian taxa, we note that B. ouricuriensis is superficially similar to Santanichthys diasii which is also found in the Aptian-Albian Araripe Basin (MAISEY, 1991; SILVA SANTOS, 1995). However, if both taxa are accurately examined, B. ouricuriensis can be distinguished from S. diasii by certain features pointed out herein in the diagnosis. The morphological pattern of jaws, with large supramaxillae, maxilla with a dentigerous lamina, and dentary with a cluster of a few minute conical teeth near symphysis; and the caudal endoskeleton pattern are enough to separate B. ouricuriensis from S. diasii. The caudal endoskeleton shows particularly primitive features when compared to S. diasii (Fig.10), such as the absence of stegural, a higher number of hypurals (six instead of five), and absence of compound centra (first preural + first ural centra).

Scombroclupeoides scutata from the lower Cretaceous of the Recôncavo Basin (WOODWARD, 1942; SILVA SANTOS, 1995) differs from B. ouricuriensis mainly by the presence of an edentulous dentary with the leptolepid notch; three uroneurals, the first one producing an anterior well-developed outgrowth (see PATTERSON & ROSEN, 1977; Figueiredo, in press), and the presence of a second hypural not fused with the first ural centrum. They share the absence of skull roof fontanels and the presence of two smooth supramaxillae.

Clupavus brasiliensis is a clupavid fish from the lower Cretaceous of the Tucano Basin (SILVA SANTOS, 1985). The systematic position of the family Clupavidae is uncertain, it is either a clupeiform (e.g., TAVERNE, 1977) or an ostariophysan (GAYET, 1981, 1985). Its placement into the Ostariophysi is due to the probable presence of a Weberian apparatus. Nowadays, Clupavidae is restricted to the genera Clupavus Arambourg, 1950 and Lusitanichthys Gayet, 1981 (TAVERNE, 2001). Comparing C. brasiliensis with B. ouricuriensis, the presence of both lower and upper jaws toothless, connection of the supraorbital and infraorbital sensory canals, compound centra formed by the fusion of first preural with first ural centra, pleurostyle, and higher number of uroneurals (see SILVA SANTOS, 1985) are enough to separate the former from the latter.

In the 1990’s, some authors proposed a close relationship between Ostariophysi and Clupeomorpha (e.g., PATTERSON, 1994; LECOINTRE & NELSON, 1996; JOHNSON & PATTERSON, 1996; ARRATIA, 1997, 1999). It was formalized in a new taxon currently named Otocephala (JOHNSON & PATTERSON, 1996). According to definition of this clade by ARRATIA (1999), Beurlenichthys shares with it at least

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one derived feature: in ontogeny, primitively the second hypural fuses to the first ural centrum (Fig.8). In addition, there is a derived fusion of hemal arches and centra anterior to the second preural centrum (see LECOINTRE & NELSON, 1996).

Based on features of the caudal skeleton such as complete neural spine associated with the second preural centrum, a free first hypural spaced from the centrum, fusion between second hypural and first ural centrum, and an elongate free second ural centrum, FOREY (1973) placed Ornategulum sardinioides in Clupeomorpha. In a first attempt to classify Beurlenichthys, FIGUEIREDO & GALLO (2001) also placed it into Clupeomorpha mainly due to fusion of the second hypural to the first ural centrum. But, according to ARRATIA (1999), this feature is not a synapomorphy of Clupeomorpha as claimed by GRANDE (1985). She noted that this fusion associated with the presence of a free first hypural are found in extant and fossil (e.g., Ornategulum sardinioides) clupeomorphs as well as in some extant ostariophysans (e.g., Saccodon wagneri) and in the varasichthyid Luisichthys. In addition, she affirmed that those features were not observed in other teleostean taxa.

As far as is known, the unique nominal species of a clupeomorph fish from the Araripe Basin is Santanaclupea silvasantosi Maisey, 1993. While studying that species, MAISEY (1993) examined the DGM 683-P (herein proposed as the holotype of Beurlenichthys ouricuriensis) and on the basis of cranial and caudal skeletons, he considered this specimen a Clupeomorpha and belonging to Santanaclupea silvasantosi. After examining in detail DGM 683-P together with additional material from the Sergipe-Alagoas Basin, we became able to separate those species as presented below.

The snout of Beurlenichthys is short and obtuse versus prolonged and pointed in Santanaclupea. The skull roof of Beurlenichthys lacks preepiotic fossa and temporal fenestra. In addition, the sensory canals of the head are bone enclosed and externally recognized by a conspicuous tubular ridge on the surface. The lower and upper jaws of Santanaclupea are engraulid-type, bearing a well defined single row of teeth and lacking clustered teeth near symphysis of the dentary. The premaxilla of the Beurlenichthys is very different from that found in Santanaclupea obeying a pattern found in certain osmeroid fishes (see PATTERSON, 1970) with a moderate alveolar and reduced ascending processes. The supramaxillae of Santanaclupea are small and placed well behind on the posterodorsal border of the maxilla. The quadrate-mandibular articulation is located behind the posterior border of the orbit and the hyomandibula bears two articular condyles and is inclined obliquely backward from the braincase.

Regarding the caudal region of Beurlenichthys, we note that the parhypural is not fused to the first preural centrum. Furthermore, this taxon possesses six hypurals versus five in Santanaclupea. Both taxa also differ in relation to the presence in Beurlenichthys of a reduced anterior finger-shaped process near the base of the first hypural lying on the posterior border of the proximal end of the parhypural. In addition, Santanaclupea exhibits a fusion of hemal arches to the first and second preural centra.

The presence of a continuous series of ventral scutes in Santanaclupea separates it definitively from Beurlenichthys. In the later, both ventral and dorsal scutes are lacking.

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In sum, Beurlenichthys ouricuriensis can be recognized by a combination of primitive and derived characters which exclude it from Leptolepidae, Clupavidae, and Clupeomorpha. Notwithstanding, certain derived features (e.g., presence of epipleurals, parhypural not fused to its centrum) suggest affinities with basal euteleosts. A comprehensive phylogenetic analysis for B. ouricuriensis and other leptolepid-like fishes is needed, but this is beyond the scope of this paper.

ACKNOWLEDGEMENTS We thank Marise Sardenberg Carvalho for all facilities provided at the Museu de Ciências da Terra of the Departamento Nacional da Produção Mineral. Paulo Marques Brito (Universidade do Estado do Rio de Janeiro) kindly reviewed the manuscript. VG has research fellowship grants from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brazilian Federal Government) and from the "PROCIÊNCIA" (Rio de Janeiro State Government).

LITERATURE CITED ARRATIA, G., 1997. Basal teleosts and teleostean phylogeny. Palaeo Ichthyologica,

München, 7: 5-168. ARRATIA, G., 1999. The monophyly of Teleostei and stem-group teleosts. Consensus and

disagreements. In: ARRATIA, G. & SCHULTZE, H.P. (Eds.) Mesozoic Fishes 2 - Systematics and Fossil Record. München: Verlag Dr. Friedrich Pfeil. p.265-334.

ARRATIA, G., 2003. Leptolepis, Paraleptolepis (Teleostei) and a new fish name. Mitteilungen aus dem Museum für Naturkunde in Berlin, Geowissenschaftliche Reihe, Berlin, 6:157-159.

ARRATIA, G. & THIES, D., 2001. A new teleost (Osteichthyes, Actinopterygii) from the Early Jurassic Posidonia shale of northern Germany. Mitteilungen aus dem Museum für Naturkunde in Berlin, Geowissenschaftliche Reihe, Berlin, 4:167-187.

CAVENDER, T., 1970. A comparison of coregonines and other salmonids with the earliest known teleostean fishes. In: LINDSEY, C.C. & WOODS, C.S. (Eds.) Biology of coregonid fishes. Winnipeg: University of Manitoba Press. p.1-32.

FIGUEIREDO, F.J. & GALLO, V., 2001. A new clupeomorph fish from the Santana Formation, northeastern Brazil with an overview of Santanichthys diasii (Silva Santos, 1958). In: INTERNATIONAL MEETING ON MESOZOIC FISHES – SYSTEMATICS, PALEOENVIRONMENTS AND BIODIVERSITY, 3., Serpiano-Monte San Giorgio. Abstract Book…, 2001, p.27.

FOREY, P.L., 1973. A primitive clupeomorph fish from the Middle Cenomanian of Hakel, Lebanon. Canadian Journal of the Earth Sciences, Ottawa, 10:1302-1318.

GAYET, M., 1981. Contribution à l'étude anatomique et systématique de l'ichthyofaune cénomanienne du Portugal. Deuxième partie: les Ostariophysaires. Communicações dos Serviços Geológicos de Portugal, Lisboa, 67:173-190.

GAYET, M., 1985. Contribution à l'étude anatomique et systématique de l'ichthyofaune cénomanienne du Portugal. Troisième partie: complément à l'étude des Ostariophysaires. Communicações dos Serviços Geológicos de Portugal, Lisboa, 71:91-118.

GAYET, M., 1994. Fishes from the Lower Cretaceous (Hauterivian?) of Wadi-el-Maluh (Israel). Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, Stuttgart, 194(1):73-93.

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