Gondwanasuchus scabrosus gen. et sp. nov., a new terrestrial predatory crocodyliform...

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Universidade Federal do Rio de Janeiro, Centro de Cincias Matemticas e da Natureza, Instituto de Geocincias, Departamento de Geologia, Av. Athos da Silveira Ramos, 274,

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Adamantina Formation (sensu Paula e Silva, 2003; Paula e Silvaet al., 2005) that includes six species: (1) Baurusuchus pachecoiPrice, 1945; (2) B. salgadoensis Carvalho, Campos & Nobre, 2005; (3)B. albertoi Nascimento and Zaher, 2010; (4) Stratiotosuchus max-hechti Campos, Suarez, Riff & Kellner, 2001; (5) Campinasuchusdinizi Carvalho, Teixeira, Ferraz, Ribeiro, Martinelli, Neto, Sertich,

Montefeltro et al., 2011).Here we describe a new baurusuchid based on a well-preserved

partial skull and mandible from the Adamantina Formation(TuronianeSantonian). This material was found in close associationwith a large specimen of Baurusuchus salgadoensis, and at the samestratigraphic horizon of Armadillosuchus arrudai Marinho andCarvalho, 2009 (Marinho et al., 2011), showing the contempora-neous occurrence of these crocodyliform taxa (Fig. 1). The newtaxon represents themost distinctive baurusuchid known to date in

* Corresponding author.

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Cretaceous Research xxx (2013) 1e8E-mail address: [email protected] (T.S. Marinho).1. Introduction

The Late Cretaceous continental Bauru Basin of southeasternBrazil has yielded a rich crocodyliform fauna. Five meso-eucrocodylian families are recognized from the 300 m-thick sedi-ments of the Adamantina and Marlia formations: baurusuchids,sphagesaurids, notosuchids, peirosaurids, and trematochampsids(e.g., Price, 1945, 1950, 1955; Carvalho and Bertini, 1999; Carvalhoet al., 2005, 2007, 2010a, 2011; Marinho and Carvalho, 2009; Ioriand Carvalho, 2009, 2011). Among these, the Baurusuchidae is themost diverse and abundant crocodyliform family found in the

Cunha, Cunha & Ferraz, 2011; and (6) Pissarrachampsa seraMontefeltro, Larsson & Langer, 2011.

Baurusuchids are terrestrial crocodyliforms regarded as activecursorial predators, based on dental, cranial, and postcranial fea-tures (Price, 1945; Riff and Kellner, 2011; Vasconcellos andCarvalho, 2007). The distribution of these animals during the LateCretaceous is exclusively Gondwanan, with Cynodontosuchus rothiand Wargosuchus australis from the Argentinean Bajo de La CarpaFormation (Neuqun Basin), Pabwehshi pakistanensis from the PabFormation of Pakistan plus the Brazilian species (Woodward, 1896;Wilson et al., 2001; Martinelli and Pais, 2008; Carvalho et al., 2011;Article history:Received 27 August 2012Accepted in revised form 30 March 2013Available online xxx

Keywords:Gondwanasuchus scabrosusBaurusuchidaeCrocodyliformesBauru BasinLate Cretaceous0195-6671/$ e see front matter 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.cretres.2013.03.010

Please cite this article in press as: Marinho(Mesoeucrocodylia: Baurusuchidae) from thj.cretres.2013.03.010a b s t r a c t

Baurusuchids are among the most common and diverse crocodyliform fossils from the Late CretaceousBauru Basin of Brazil. This inland continental basin was the habitat of a rich crocodyliform fauna con-taining ve mesoeucrocodylian families, of which the Baurusuchidae represents highly specializedpredatory crocodyliforms of terrestrial habits as indicated by their dental, cranial, and postcranial fea-tures. The large size they achieved, together with likely predatory adaptations, would suggest theycompeted and occupied theropod ecological niches in the Bauru Basin. Here we describe Gondwana-suchus scabrosus gen. et sp. nov., a medium-sized baurusuchid with a strongly laterally compressed skull,bearing unique dentition with deep apicobasal sulci and probably well-developed binocular vision. Thecranial and dental features in Gondwanasuchus suggest that this active predator would have fed on smallvertebrates and took the role of small theropods in terrestrial guild. Gondwanasuchus is the mostdistinctive baurusuchid known to date and enriches the knowledge on these important Gondwananterrestrial predatory crocodyliforms.

2013 Elsevier Ltd. All rights reserved.Bloco F, Ilha do Fundo e Cidade Universitria, Rio de Janeiro, RJ 21949-900, BrazilGondwanasuchus scabrosus gen. et sp. ncrocodyliform (Mesoeucrocodylia: BauruBauru Basin of Brazil

Thiago da Silva Marinho a,*, Fabiano Vidoi Iori b, IsmFelipe Mesquita de Vasconcellos b

aUniversidade Federal do Tringulo Mineiro, Instituto de Cincias Exatas, Naturais e EducMG 38025-440, Brazilb

Cretaceou

journal homepage: www.All rights reserved.

, T.S., et al., Gondwanasuchuse Late Cretaceous Bauru Ba., a new terrestrial predatoryuchidae) from the Late Cretaceous

r de Souza Carvalho b,

, Departamento de Cincias Biolgicas, Av. Getlio Guarit, 159 Bairro Abadia, Uberaba,

SciVerse ScienceDirect

Research

evier .com/locate/CretResscabrosus gen. et sp. nov., a new terrestrial predatory crocodyliformsin of Brazil, Cretaceous Research (2013), http://dx.doi.org/10.1016/

eousT.S. Marinho et al. / Cretac2that it displays a strongly laterally compressed skull, dentitionbearing deep apicobasal sulci and probably binocular vision, thusadding a new bauplan to the diversity of these Gondwanancrocodyliforms.

The institutional abbreviations used in this article are as follows:UFRJ DG, Departamento de Geologia, Universidade Federal do Riode Janeiro, Rio de Janeiro, Brazil; CPP, Centro de Pesquisas Paleon-tolgicas Llewellyn Ivor Price, Peirpolis, Uberaba, Minas Gerais,Brazil.

2. Geological setting

Gondwanasuchus was found in an outcrop of the AdamantinaFormation (TuronianeSantonian of Bauru Basin; sensu Dias Britoet al., 2001) at Fazenda Buriti Paleontological Site, General Sal-gado County, Northwestern So Paulo State, Brazil (Carvalho et al.,2010b) (Fig.1). This outcrop is composed of ne-grained sandstonesand siltstones with intercalations of red oxidizedmudstones, whichwere deposited on an extensive alluvial plain reworked by uvialsystems alongside scattered shallow ephemeral lakes in an arid orsemi-arid seasonal climate (Fernandes and Coimbra, 1996; Garciaet al., 1999; Goldberg and Garcia, 2000; Fernandes and Basilici,2009). The Bauru Basin was formed during the early breakup ofGondwana associated with the opening of the South Atlantic Ocean(Fernandes and Coimbra, 1996).

The fossil assemblage of Fazenda Buriti Paleontological Site iscomposed mostly by baurusuchid remains, represented by skulls,

Fig. 1. Lithostratigraphic map of the eastern part of the Bauru Basin (modied from FernanFazenda Buriti Paleontological Site, General Salgado County, Brazil.

Please cite this article in press as: Marinho, T.S., et al., Gondwanasuchus(Mesoeucrocodylia: Baurusuchidae) from the Late Cretaceous Bauru Baj.cretres.2013.03.010Research xxx (2013) 1e8semi-articulated skeletons and complete specimens (Carvalhoet al., 2010b). In addition, these outcrops have also yielded speci-mens of Armadillosuchus arrudai, anilioid snake vertebrae, inver-tebrate ichnofossils, and coprolites and egg remains attributed tocrocodyliforms (Zaher et al., 2003; Arruda et al., 2004; Carvalhoet al., 2010b; Marinho et al., 2011).

3. Systematic paleontology

Crocodyliformes Hay, 1930 (sensu Clark, in Benton and Clark, 1988)Mesoeucrocodylia Whetstone and Whybrow, 1983 (sensu Clark, inBenton and Clark, 1988)Notosuchia Gasparini, 1971Baurusuchidae Price, 1945Pissarrachampsinae Montefeltro, Larsson and Langer, 2011Gondwanasuchus gen. nov.

Etymology: Generic name refers to the southern paleocontinentGondwana as an allusion to the Gondwanan distribution of theBaurusuchidae, plus souchus, Greek for crocodile, leading to Latin,suchus.

Diagnosis: As for the type and only known species.

Type species: Gondwanasuchus scabrosus

Gondwanasuchus scabrosus sp. nov.

des and Coimbra, 2000), and stratigraphic prole of the Adamantina Formation at the

scabrosus gen. et sp. nov., a new terrestrial predatory crocodyliformsin of Brazil, Cretaceous Research (2013), http://dx.doi.org/10.1016/

Holotype: UFRJ DG 408-R consists of well-preserved partial skullandmandible, lacking the skull roof, basicranial region and bones ofthe right side posterior to the anterior orbital margin (Figs. 2 and 3)and the remains of ve cervical vertebrae and some associatedcervical ribs.

Locality and horizon: The specimen was collected at FazendaBuriti Paleontological Site, General Salgado County, NorthwesternSo Paulo State, Brazil, from the Adamantina Formation (TuronianeSantonian), Bauru Basin.

Etymology: Specic name from the Latin, scabrosusmeaning roughdue to the anteroventrally sloped palpebrals of the holotype thatgives it a scabrous rough-look.

Diagnosis: Baurusuchidae with following combination of charac-ters: an overhanging anterior portion of the rostrum containingfour premaxillary teeth, which is separated from the maxilla by adeep notch for accommodating an enlarged lower tooth; hetero-dont dentition; ve maxillary teeth; teeth with ve or six wide anddeep apicobasal sulci, making each tooth corrugated in cross-section; highly compressed maxillary teeth bearing nelyserrated carinae; highly compressed skull and mandible; smallantorbital fenestra; laterally projected slender jugal; laterallypositioned postorbital; anteriorly facing orbits; rostrum slopedanteroventrally; nasalefrontal contact separating the prefrontals;

feature is the extreme lateral compression observed along thesagittal axis.

The premaxilla is subquadrangular in lateral view, and boundsthe external nares except for a small anterodorsal portion. Anteri-orly, the premaxillae project dorsally to form a delicate internarialbar that is in contact with the anteriormost projection of the nasals.The external nares are subcircular and laterally positioned, boun-ded anteriorly, ventrally and posteriorly by the premaxilla andanterodorsally by the nasal. Posteriorly, between the premaxillaand maxilla is the notch where a hypertrophied mandibular tooth(possibly the fourth) is housed during occlusion. The externalpremaxillaemaxilla suture is located dorsal to the notch, that issmall and posterodorsally oriented. The ventral margin of thepremaxilla is parallel to the palatal axis, while its dorsal margin isslightly sloped anteroventrally and contacts the nasal up to theexternal nares. The posterodorsal extremity of the premaxilla isslightly rugose as are the maxilla and nasal; the ventral border ofthe premaxilla is smooth and shows two neurovascular foramina inassociation with the third and fourth alveoli. On each premaxillafour alveoli, with teeth of circular cross-section and distally curved,are preserved.

The maxilla is deep, its anterior border is almost perpendicularto its ventral margin; the dorsal margin is sloped anteroventrally,and the posterior maxillary margin is oriented anterodorsally at anangle of almost 45, making the maxilla subtriangular. The maxillacontacts the jugal along its anteroventral region, posterior to the

T.S. Marinho et al. / Cretaceous Research xxx (2013) 1e8 3dorsal margin of the jugal parallel to the palatal axis along all itslength; laterally compressed mandible without lateral broadeningat the symphysis at the level of the mandibular hypertrophiedteeth.

4. Description

Skull

The snout represents almost half of the estimated total skulllength. The skull is triangular in dorsal view, and the most peculiarFig. 2. Holotype of Gondwanasuchus scabrosus gen. nov. et sp. nov. (UFRJ DG 408-

Please cite this article in press as: Marinho, T.S., et al., Gondwanasuchus(Mesoeucrocodylia: Baurusuchidae) from the Late Cretaceous Bauru Baj.cretres.2013.03.010lacrimal contact, and contacts the ectopterygoid ventrally of thejugal. The contact of the maxilla and lacrimal is dorsal of themaxillaejugal contact and presents a small antorbital fenestra nearthemiddle of its depth. The antorbital fenestra is oval with its majoraxis anterodorsally oriented. Posteriorly, near the antorbitalfenestra, the maxillae show concave regions in its lateral surfacethat extend to the lacrimals (Figs. 1D and 2D). The maxilla is gentlyrugose on its anterodorsal portion and is smoother around theantorbital fenestra. The ventral maxillary region is smooth andbears small neurovascular foramina in association with its alveoli.Despite the mandibles occlusion, it is possible to observe that theR) in lateral view (A), dorsal view (B), palatal view (C) and anterior view (D).


v. (Ul; D:: P

eouspalatal region of themaxillae is narrow and convex anteriorly to thesuborbital fenestrae, with a medial groove between them. Each

Fig. 3. Schematic drawings of holotype of Gondwanasuchus scabrosus gen. nov. et sp. noAnatomical abbreviations: An: Angular; anf: antorbital fenestra; Ap: Anterior palpebraM: Maxilla;mf: mandibular fenestra; N: Nasal; or: orbit; Pa: Palatine; Pfr: Prefrontal; PmSurangular; sf: supraorbital fenestra; sof: suborbital fenestra; Sp: Splenial.

T.S. Marinho et al. / Cretac4maxilla bears ve alveoli with all teeth preserved except the secondleft maxillary tooth.

The dorsal region of the lacrimal forms a laterally extended shelf(Fig. 2D) that contacts the nasal and prefrontal, and supports theanterior palpebral that overlaps it. The lacrimal contact with theanterior process of the jugal is not sutured. The lacrimal is notornamented laterally, and the lacrimal foramen lies below thelacrimal shelf. In anterior view, the lacrimal is dorsoventrallycurved because of the concavity of the anterior orbital wall(Fig. 2D).

The jugal is slender and long, extending from the anterior orbitaledge to the posterior corner of the infratemporal fenestra. Thecontact of the jugal with the maxilla is smooth whereas the contactof the jugal and quadratojugal is heavily sutured. Transversally, thejugal is narrow with its dorsal region projected laterally, forming alongitudinal ridge. The anterior process of the jugal is the deepestportion, decreasing posteriorly. The longitudinal ridge is lower,becoming accentuated and more laterally projected at the rear.Ventral to the infratemporal fenestra, the jugal ridge is horizontal,thus parallel to the palatal axis; it is dorsoventrally compressedforming a slight dorsal curvature in the skulls posterior ventralmargin. Due to the lateral projection of the ridge, the postorbitalbar is located medially to the jugals dorsolateral margin. Thepostorbital bar is rod-like, circular in cross-section, medioposter-iorly curved and constitutes the lower half of the posterior orbitalmargin. The jugal is ornamented with subdued rugosities at itslateroventral region, by small pits at the ridges mid-region, and byslightly larger pits at its lateroventral region. The quadratojugal isposteriorly broken, but it projects anteriorly and contacts thepostorbital at the infratemporal fenestras apex. The orbit is large,anteriorly placed, longer than deep, with its rim composed by thelacrimal anteriorly, by the jugal ventrally, by the jugals postorbital

Please cite this article in press as: Marinho, T.S., et al., Gondwanasuchus(Mesoeucrocodylia: Baurusuchidae) from the Late Cretaceous Bauru Baj.cretres.2013.03.010process posteroventrally, and by the postorbital posterodorsally.Due to the missing skull roof bones, only the palpebrals seem to

FRJ DG 408-R) in lateral view (A), dorsal view (B), palatal view (C) and anterior view (D).Dentary; en: external nares; F: Frontal; itf: infratemporal fenestra; J: Jugal; L: Lacrimal;remaxilla; Po: Postobital; Pp: Posterior palpebral; Pt Pterygoid; Qj: Quadratojugal; San:

Research xxx (2013) 1e8limit the orbit dorsolaterally in the location of the frontal. Inanterior view, the postorbital bar is more laterally positioned thanthe anterior orbital wall (due to the medial exure of the lacrimal)and snout, exposing the orbit anteriorly (Figs. 1D and 2D). Theanterior position of the large orbits suggests the presence of ahighly advanced binocular vision in Gondwanasuchus, while thelow and narrow snout cleared its sight lines, as seen in theropoddinosaurs, indicating its visual acuity for predation (Stevens, 2006).

The postorbital is broken posterodorsally. The anterior region ofthe infratemporal fenestra is limited by the jugals postorbitalprocess, ventrally by the jugal, posteriorly by the quadratojugal andby the postorbital at its dorsal apex. Its descending process corre-sponds to half of the orbits depth and is a very thin structure. Theposterior surface of the postorbital is transverse to the sagittal axisand forms a 90 angle with its preserved posterolateral portion.Dorsally, a small surface is preserved, fused to the posteriorpalpebral. The infratemporal fenestra is subtriangular, with thedorsal apex positioned at its anterior half. The antero-posteriorlength of the fenestra is w2/3 of the orbits length and w1/2 ofits depth. The fenestra faces slightly dorsally due to the position ofthe postorbital bar and quadratojugal.

The nasal is long, narrow, with its lateral and medial marginsparallel along its anterior half, and is ornamented by wrinkles andsmall pits. The nasal broadens abruptly at its middle region and isalmost twice as wide at its posterior half, but retains parallel lateraland medial margins (Fig. 2B). Posteriorly, the nasal contacts theprefrontal and anterior palpebral, and projects posteriorly to con-tact the frontal (Fig. 2D). The posterior half of the nasal is concavemedially. The nasal projects anteriorly to form the dorsal portion ofthe internarial bar in conjunction with the premaxilla.

The palatine is narrow and slightly shorter than the suborbitalfenestra. The palatine is slightly broader posteriorly than anteriorly


posterodorsally oriented. The dentary limits the anterodorsalportion up to almost half of the fenestras length and a smallanteroventral region. The surangular borders the dorsal half of thefenestra up to its posterior end where the mandible is broken. Theangular is represented only by a small portion and bounds theexternal mandibular fenestra ventrally.

Dentition

The dentition has the most distinctive traits of Gondwanasuchusscabrosus with the development of vertical grooves on the outersurface. The teeth bear ve or six deep and wide apicobasal sulcithat converge apically and are interspersed with ridges (Fig. 4).There are four premaxillary and ve maxillary teeth. The premax-illary teeth curve over their distal half, have circular cross-sectionsand lack carinae. Of note, the teeths surfaces have ve or six api-cobasal sulci (Fig. 4A). The rst premaxillary tooth displays thestrongest curvature which grant it a hooked aspect. The second andthird teeth are similar in morphology, with virtually identical

eous Research xxx (2013) 1e8 5in palatal view. Themedial contact between the palatines is straightand the palatal surface is at. The contact of the maxilla and pal-atine is sutured and transversely straight at the anterior suborbitalborder. The palatine contacts the ectopterygoid with a smallposterolateral surface in palatal view. Transversally the palatine istriangular, with a 90 ventromedial angle.

In palatal view, the ectopterygoid of Gondwanasuchus scabrosusis slender, in contrast to those of other baurusuchids, and partiallycaps the ventral pterygoid border, composing the posterolateralportion of the palate. The posterolateral ectopterygoid ramus ex-tends to the pterygoids ventral extremity, near the ventral marginof the angular. The angle between the anterolateral ramus of theectopterygoid and its anteromedial ramus is w75, correspondingto the posterior margin of the suborbital fenestra. The ectopter-ygoid contacts the maxilla ventrally to the jugal below the middleof the ventral orbital border. Only a small portion of the pterygoid ispreserved, and in part, it is supported by sediment. The pterygoidwings diverge w60 to the sagittal axis and w45 to the palatalaxis. The contact with the palatine is vertical, and dorsally thepterygoid has a small anterior projection.

The anterior palpebral is large, and bears a few marginal ru-gosities; it is not sutured to the adjacent bones. The bone is sub-triangular with anterior, medial, and posterior expansion, and islonger than the major axis of the orbit. In lateral view, it gentlyslopes anteroventrally. The anteromedial border displays discreteserration-like tubercles, while the posteromedial border is slightlyconcave and smooth. The anteromedial border is projected medi-ally forming a sharp crest above the prefrontal. In dorsal view, theanteromedial border is parallel to the sagittal axis, while the lateralborder is curved like the jugal ridge. The posterior palpebral is verysmall and subtriangular, and is ornamented by rugosities and smallpits. Its anteromedial border shows discreet serration-like tuber-cles as in the anterior palpebral. The contact of palpebrals is notpreserved, but its extremities could possibly touch, forming an ovalsupraorbital fenestra with an antero-posterior major axis.

Only the anteriormost portion of the prefrontals and frontalwere preserved. The preserved portion of the prefrontal is anteriorlyrounded and posteriorly narrower, granting it a teardrop shape.The frontal projects anteriorly, medially to the prefrontals making asmall contact to the nasals. The frontal broadens posteriorly.

Mandible

Like the skull, themandible is strongly compressed laterally. Thedentary is transversely narrow and shallow. Its depth remainsalmost constant throughout its length. Posterior to the mandibularsymphysis, the dentary is weakly concave at the third maxillarytooth. The symphyseal region is extremely narrow in contrast to theother baurusuchids that shows expansion at the fourth dentaryalveolus. The anteroventral edge of the dentary is oriented ante-rodorsally in a 45 angle in relation to the palatal axis. Themandible is heavily ornamented with several small rounded andslit-like pits, especially at the symphyseal region, extending to theposition of the fth maxillary tooth. Small foramina are sparselydistributed posteriorly to the level of the mid orbital length.

The splenial is almost at and smooth. In palatal view, it ispossible to observe the contact of the splenials with the dentaries atthe posterior portion of the mandibular symphysis. The splenialsare sutured together, whereas the splenial-dentary contact isoverlapping. The intermandibularis oralis foramen is large and oval,with its major axis positioned anteroposteiorly. Posteriorly, thesplenial composes the anterior wall of the inner mandibularfenestra, and contacting posteroventrally the angular. The externalmandibular fenestra has a teardrop shape with the anterior ex-

T.S. Marinho et al. / Cretactremity anteroventrally oriented and its posterior extremity

Please cite this article in press as: Marinho, T.S., et al., Gondwanasuchus(Mesoeucrocodylia: Baurusuchidae) from the Late Cretaceous Bauru Baj.cretres.2013.03.010crown heights. The fourth premaxillary and the rst maxillarytooth are very small and positioned adjacent to the premaxillaemaxilla notch. The second maxillary tooth is slightly laterallycompressed, its crown is lower than those of the third and fourthmaxillary teeth, and bears a distal serrated carina at their apicalregion. The third and fourth maxillary teeth are laterally com-pressed, with mesial and distal serrated carinae (Fig. 4B). The thirdmaxillary tooth is the largest of the upper jaw. The fth maxillarytooth is similar in morphology to the third and fourth maxillaries,except that its crown is much lower. Because the mandible isoccluded, only one mandibular tooth (probably the fourth) isobserved at the premaxillaemaxilla notch. This mandibular tooth ishighly enlarged, but similar in morphology to the third and fourthmaxillary teeth and bears a distal serrated carina. The mandibularand maxillary teeth show three apicobasal sulci on their labialsurfaces, and there are likely three additional sulci on the lingualsurfaces. The serrated carinae observed in the teeth of Gondwana-suchus are composed of chisel-like, subquadrangular denticles,distributed with a density of ve denticles per millimeter along themesial carinae, and four denticles per millimeter along the distalcarinae. The serrations are morphologically homogeneous, but theyare deeper at the mid-region of the carinae and were likely usedlike a steak knife for cutting esh (Fig. 4B).

Both the upper jaws bear teeth in all stages of eruption and showsize gradation on alternate tooth rows from which the tooth

Fig. 4. The dentition of Gondwanasuchus scabrosus gen. nov. et sp. nov. (UFRJ DG 408-R); Second right premaxillary tooth (A) and fourth right maxillary tooth (B). Abbre-

viations: m 1e5: maxillary tooth and corresponding position 1e5; pm 1e4: pre-maxillary tooth and corresponding position 1e4.


replacement pattern can be inferred. Alternations of younger andolder teeth are evident in the upper jaw. The teeth, irrespective ofsize, are rmly held in the alveoli in thecodont fashion. In the odd-numbered series of the upper jaw, teeth one (pm1) and three(pm3), ve (m1) and seven (m3) form two separate series ofincreasing size toward the rear; in the even-numbered teeth, six(m2) and eight (m4) show a similar trend of increasing size (Fig. 4).Teeth four (pm1) and ve (m1) are erupted at the level of thealveolus, whereas tooth nine (m5) is slightly above the alveolarborder (Fig. 4). Thus, the upper jaw exhibits waves of toothreplacement proceeding from back to front as in other reptiles(Edmund, 1960).

5. Discussions and conclusions

Gondwanasuchus scabrosus exhibits the following baurusuchidsynapomorphies: a laterally compressed rostrum, a prominentpremaxillaemaxilla notch for the reception of the hypertrophiedmandibular tooth, medial contact of the prefrontals with abbrevi-ated frontalenasal contact, reduced dentition, caniniform maxil-lary teeth, and ziphodont dentition (Price, 1945; Gasparini, 1972;Carvalho et al., 2005; Martinelli and Pais, 2008). Montefeltroet al. (2011) proposed the Subfamily Pissarrachampsinae toinclude Pissarrachampsa sera and Wargosuchus australis. Both taxa

following autapomorphies: teeth with wide and deep apicobasalsulci, an enlarged, caniniform fourth dentary tooth, highly com-pressed skull and mandible, laterally projected slender jugal, andanteriorly facing orbits with a large component of stereoscopicvision (Fig. 5).

The skull of Gondwanasuchus scabrosus is oreinirostral, withvertical lateral snout walls, short and very narrow snout (sensuBusbey, 1995). Oreinirostral snouts are stronger than platyrostralsin anterior biting (Rayeld and Milner, 2008), but would be moresusceptible to the stresses caused by medially directed forces andincreases of axial torque generated by the rolling behavior of extantplatyrostral crocodilians (Bolt, 1974). These resistance characteris-tics of oreinirostric skulls suggest that terrestrial crocodyliformswould not invoke rolling as a mechanism for the destabilizationand dismemberment of prey, but would possibly adopt methods toacquire and subjugate prey similar to Varanus komodoensis, assuggested by Busbey (1995).

In lateral view, the nasals of Gondwanasuchus scabrosus aremoreanteroventrally sloped than other baurusuchids, particularly whencompared to Baurusuchus and Stratiotosuchus where the nasals arealmost parallel to the palatal axis (Carvalho et al., 2005; Camposet al., 2001). In anterior view, G. scabrosus has the most stronglylaterally compressed skull of all baurusuchids, with a palatal widthof 18 mm and snout depth of 28 mm between the third maxillary

T.S. Marinho et al. / Cretaceous Research xxx (2013) 1e86display a posterior portion of the nasal dorsal surface with a broad,rugose depression, prefrontals approximating along their medialedges anteriorly allowing a reduced frontalenasal contact, and thepresence of a midline longitudinal depression on the anteriorportion of the frontal. Campinasuchus dinizi also has a contact be-tween the frontal and nasals through the medial approach of theprefrontals (Carvalho et al., 2011), as in W. australis and P. seracharacterizing it as a Pissarrachampsinae. In addition, G. scabrosuspresents all the diagnostic features proposed by Montefeltro et al.(2011) for the Pissarrachampsinae, indicating that this new spe-cies represents a baurusuchid more closely related to W. australis,C. dinizi and P. sera than to other baurusuchids, such as Baurusuchusand Stratiotosuchus. In these latter genera, the two prefrontalstouch medially precluding a nasalefrontal contact. Despite theshared feature at the skull roof, G. scabrosus is characterized by theFig. 5. Life reconstruction of Gondwanasuchus scabrosus gen. nov. et sp. nov. right lat

Please cite this article in press as: Marinho, T.S., et al., Gondwanasuchus(Mesoeucrocodylia: Baurusuchidae) from the Late Cretaceous Bauru Baj.cretres.2013.03.010teeth. The lateral maxillary wall is straight and more vertical inanterior view than in Baurusuchus pachecoi, B. salgadoensis, Strat-iotosuchus maxhechti, Wargosuchus australis, Campinasuchus diniziand Pissarrachampsa sera; these species have dorsomedially curvedmaxillae, with a broader dorsal exposure (see Carvalho et al., 2005;Campos et al., 2001; Martinelli and Pais, 2008; Carvalho et al., 2011;Montefeltro et al., 2011).

The external nares of Gondwanasuchus scabrosus is similar tothat of the other baurusuchids with anterolateral openings exceptfor Stratiotosuchus maxhechti, in which the external nares arelocated more anterodorsally (Montefeltro et al., 2011). The pre-maxilla of G. scabrosus is subrectangular in lateral view, propor-tionally longer and shallower than in other baurusuchids. The onlyexception is S. maxhechti in which the premaxilla projects poster-odorsally to the rostral notch.eral (A), anterior (B), dorsal (C) and oblique (D) views. Art by Rodolfo Nogueira.


Rodrigues, R., 2001. Grupo Bauru: uma unidade continental do Cretceo no

eousGondwanasuchus scabrosus dentition is similar in tooth numberto Baurusuchus pachecoi, B. salgadoensis and Campinasuchus diniziwith four premaxillary and ve maxillary teeth, but differs fromStratiotosuchus maxhechti which contains three premaxillary andve maxillary teeth, and Pissarrachampsa sera with three premax-illary and four maxillary teeth (Campos et al., 2001; Riff and Kellner,2011; Montefeltro et al., 2011). Campinasuchus dinizi (specimen CPP1236) bears ve teeth at the left maxilla and only four at the rightmaxilla. This difference in the number of teeth at the left and rightmaxilla of CPP 1236 seems to be related to the size of the rostralnotch, where the right notch is broader posteriorly and obliteratesthe rst maxillary alveolus. The enlargement of the rostral notch ofS. maxhechti and P. seramight be related to the reduced dentition ofthese taxa, that diverge from most baurusuchids.

Baurusuchid teeth are usually smoothwith discreet longitudinaland transverse lines (Riff and Kellner, 2001). In contrast, the teeth ofGondwanasuchus are laterally compressed with serrated anteriorand posterior edges; the labial and lateral surfaces are marked byapicobasal sulci associated with coarse utings, making these teethformidable weapons. The slender and recurved premaxillary teethof Gondwanasuchus scabrosuswere probably used for catching prey,whereas the strong maxillary teeth with corrugated surface andserrated edges were deployed for puncturing and killing strugglingprey, aided by the enlarged lower caniniform tooth, which couldslide in the premaxillaemaxilla notch to provide a strong grip. Theposterior maxillary teeth are more laterally compressed than otherbaurusuchid teeth and do not show wear facets. The longitudinalsulci on the teeth of Gondwanasuchus could have provided addi-tional structural strength to prevent any break during capturingand killing prey.

Gondwanasuchus is oneof the smallest knownbaurusuchids,witha preserved skull length of 128 mm and estimated total length ofabout 150mm. The holotype presents a mosaic of juvenile and adultfeatures. Some juvenile characteristics include: loosely sutured cra-nial and mandibular elements as well as proportionally large orbits,while the well-developed ornamentation features in the cranial andmandibular bones suggest adult or subadult features (Mook, 1921).Most likely, the holotype of Gondwanasuchus scabrosus represents asubadult of a small to medium-sized species of Baurusuchidae.

Baurusuchids are considered by many authors as crocodyliformsthat occupied the role of medium to large-sized predators in theterrestrial realms of the Bauru Basin, due to the inferred terrestrialhabits of the family based on dental, cranial and postcranial featuresand to the large size that they could reach (Gasparini et al., 1993;Vasconcellos and Carvalho, 2007; Martinelli and Pais, 2008; Riff andKellner, 2011). Gondwanasuchus scabrosus clearly displays somebaurusuchid characteristics that resemble those of theropods, suchas strongly laterally compressedmaxillary teeth and skull. The snoutoverhangs anteroventrally, and the orbits aremore anteriorly placed(Figs. 2D and 3D) suggesting a highly advanced binocular vision asinferred forTyrannosaurus rexandother theropodsused toaccuratelyjudge position of prey (Stevens, 2006). Due to the oreinirostral skull,whichwould not supportmedially directed force orhigh axial torqueas well as premaxillary teeth adapted to subjugation, Gondwana-suchus most likely fed on small vertebrates and carcasses, possiblyoccupying the ecological niches of small theropods. If Gondwana-suchus could consistently engage prey with its formidable teeth, itcould have exploited a predatory niche in the absence of theropods.

Acknowledgments

Thanks are due Joo Tadeu Arruda, Kleber Varnier and SidneiBelarmino (Igeo, UFRJ) for the eld efforts and the extraction of thefossils during the campaign at General Salgado. Leonardo Borghi

T.S. Marinho et al. / Cretac(Igeo, UFRJ) is thanked for allowing the use of the Carl Zeiss

Please cite this article in press as: Marinho, T.S., et al., Gondwanasuchus(Mesoeucrocodylia: Baurusuchidae) from the Late Cretaceous Bauru Baj.cretres.2013.03.010Brasileconcepes baseadas em dados micropaleontolgicos, istopos e estra-tigrcos. Revue Palobiologique, Gneve 20, 245e304.

Edmund, A.G., 1960. Tooth replacement phenomena in the lower vertebrates. RoyalOntario Museum Life Sciences Division Contributions 52, 1e179.

Fernandes, L.A., Basilici, G., 2009. Transition of ephemeral palustrine to aeoliandeposits in a continental arid e semiearid environment (Upper CretaceousBauru Basin, Brazil). Cretaceous Research 30, 605e661.

Fernandes, L.A., Coimbra, A.M., 1996. A Bacia Bauru (Cretceo Superior, Brasil). Anaisda Academia Brasileira de Cincias 68, 195e205.

Fernandes, L.A., Coimbra, A.M., 2000. Reviso Estratigrca da Parte Oriental daBacia Bauru (Neocretceo). Revista Brasileira de Geocincias 30 (4), 717e728.

Garcia, A.J.V., da Rosa, A.A.S., Goldberg, K., 1999. Paleoenvironmental and paleo-climatic controls on early diagenetic processes and fossil records in continentalCretaceous sandstones in Brazil: a petrologic approach. Simpsio sobre o Cre-tceo do Brasil, vol. 5. UNESP, Boletim, Serra Negra, pp. 491e495.

Gasparini, Z.B., 1971. Los Notosuchia del Cretcico de Amrica del Sur como unnuevo Infraorden de los Mesosuchia (Crocodilia). Ameghiniana 8, 83e103.

Gasparini, Z.B., 1972. Los Sebecosuchia (Crocodilia) del Territorio Argentino. Con-sideraciones sobre su status taxonmico. Ameghiniana 9, 23e34.

Gasparini, Z.B., Fernandez, M., Powell, J., 1993. New tertiary sebecosuchians (Croc-Discovery V.12 Stereomicroscope used for the close-up photographsof the specimens teeth. Diego Evan Gracioso (Igeo, UFRJ) preparedthis specimen. Agustn Martinelli (Complexo Cultural e Cientco dePeirpolis, UFTM), Dr. Sankar Chatterjee (Museum of Texas TechUniversity), Dr. Atila si (Hungarian Academy of ScienceseEtvsLornd University), Dr. Peter Harries (Cretaceous Researchs Asso-ciate Editor) and an anonymous reviewer provided suggestions thatgreatly improved the manuscript. Schematic drawings seen in Fig. 3were made by Cao Scarpini and Anna Clara Rossi, the baurusuchidsketch displayed in Fig. 1 was made by Matheus Grimio and theGraphical Abstract was designed by Tito Aureliano Neto. Thisresearch was supported by Fundao de Amparo Pesquisa doEstado do Rio de Janeiro (FAPERJ), Coordenao de Aperfeioamentode Pessoal de Nvel Superior (CAPES) and Conselho Nacional deDesenvolvimento Cientco e Tecnolgico.

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T.S. Marinho et al. / Cretaceous Research xxx (2013) 1e88Please cite this article in press as: Marinho, T.S., et al., Gondwanasuchus(Mesoeucrocodylia: Baurusuchidae) from the Late Cretaceous Bauru Baj.cretres.2013.03.010scabrosus gen. et sp. nov., a new terrestrial predatory crocodyliformsin of Brazil, Cretaceous Research (2013), http://dx.doi.org/10.1016/

Gondwanasuchus scabrosus gen. et sp. nov., a new terrestrial predatory crocodyliform (Mesoeucrocodylia: Baurusuchidae) from ...1. Introduction2. Geological setting3. Systematic paleontology4. Description5. Discussions and conclusionsAcknowledgmentsReferences

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