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Reconstrucción de Proterochampsa barrionuevoi con medidas tomadas del ejemplar PVSJ 606. En gris las regiones faltantes. Escala= 10 cm/ Reconstruction of Proterochampsa barrionuevoi with measurements of specimen PVSJ 606. Missing regions shaded gray. Scale= 10 cm.
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POSTCRANIAL MATERIAL OF PROTEROCHAMPSA BARRIONUEVOI REIG, 1959 (DIAPSIDA: ARCHOSAURIFORMES) FROM THE UPPER TRIASSIC OF CENTRAL-WESTERN ARGENTINA. Proterochampsids are members of the clade Archosauriformes, a group distinguished from others because of its depressed skulls transversely expanded at the posterior end, narrow and longitudinally long sno...
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... postcraneano de P. barrionuevoi conocido hasta el momento (MCZ 3408) consistía en el complejo atlas-axis, la serie cervical, las primeras vértebras dorsales y costillas cervicales (Sill, 1967). Los nuevos materiales aquí descriptos corresponden a un ejemplar depositado en el Ins- tituto y Museo de Ciencias Naturales de San Juan (PVSJ 606) (Fig. 2). Este ejemplar presenta la serie cervical y dorsal completas, serie caudal anterior, gastralia, costillas cervica- les y dorsales, ambas escápulas, coracoides derecho, húmero, radio y ulna derechos, pelvis completa pero desarticulada y miembro posterior derecho casi completo. En rasgos genera- les, el ejemplar PVSJ 606 presenta una ...
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... algunos arcosaurios en general, pero en contraste con los dinosaurios y mamíferos (Romer, 1956), el fémur no presenta cuello femoral entre la cabeza y la diáfisis, es decir, la cabeza femoral es confluente con la diáfisis (Brusatte et al., 2008 et al., 2008; carácter 145), con desarrollo posteroventral, y excede el tercio proximal del fémur ( Fig. 11.2). La cara medial del cuarto trocánter es mayormente convexa y la lateral es lisa y plana. Medialmente al cuarto trocánter se observa una fosa de escasa profundidad. Si bien los cóndilos distales del fémur de PVSJ 606 no estaban bien osificados, puede observarse que el cóndilo fibular es más grande que el tibial (Brusatte et al., 2008; ...
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... los cóndilos distales del fémur de PVSJ 606 no estaban bien osificados, puede observarse que el cóndilo fibular es más grande que el tibial (Brusatte et al., 2008; carácter 146) encontrándose ambos al mismo nivel (Figs. 11.3-4). En vista posterior puede distinguirse entre ambos cóndilos una fosa poplítea somera, de escaso desarrollo longitudinal (Figs. 11.1-2). En vista anterior, so- bre el extremo distal, se observa una leve depresión de corto recorrido que corresponde al surco intercondilar. Tibia. La tibia es más corta que el fémur (Brusatte et al., 2008; carácter 148), representando su longitud el 73;3 de la longitud total del fémur (Benton, 2004). La tibia de P. barrionuevoi tiene ...
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... recorrido que corresponde al surco intercondilar. Tibia. La tibia es más corta que el fémur (Brusatte et al., 2008; carácter 148), representando su longitud el 73;3 de la longitud total del fémur (Benton, 2004). La tibia de P. barrionuevoi tiene diáfisis de sección elíptica y extremos ex- pandidos anteroposteriormente poco torsionados entre sí (Figs. 12.1-2). El extremo proximal presenta superficie ar- ticular rugosa dirigida posteroproximalmente ( Fig. 12.2). La cresta cnemial está poco desarrollada (Brusatte et al., 2008; carácter 149) y la separación entre ésta y el contorno de la diáfisis en vista anterior no es prominente (Figs. 12.1-3). Posteriormente a la cresta cnemial se ...
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... al., 2008; carácter 148), representando su longitud el 73;3 de la longitud total del fémur (Benton, 2004). La tibia de P. barrionuevoi tiene diáfisis de sección elíptica y extremos ex- pandidos anteroposteriormente poco torsionados entre sí (Figs. 12.1-2). El extremo proximal presenta superficie ar- ticular rugosa dirigida posteroproximalmente ( Fig. 12.2). La cresta cnemial está poco desarrollada (Brusatte et al., 2008; carácter 149) y la separación entre ésta y el contorno de la diáfisis en vista anterior no es prominente (Figs. 12.1-3). Posteriormente a la cresta cnemial se encuentran los cóndilos proximales lateral y medial. Ambos cóndilos se ubican en un plano localizado más ...
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... ex- pandidos anteroposteriormente poco torsionados entre sí (Figs. 12.1-2). El extremo proximal presenta superficie ar- ticular rugosa dirigida posteroproximalmente ( Fig. 12.2). La cresta cnemial está poco desarrollada (Brusatte et al., 2008; carácter 149) y la separación entre ésta y el contorno de la diáfisis en vista anterior no es prominente (Figs. 12.1-3). Posteriormente a la cresta cnemial se encuentran los cóndilos proximales lateral y medial. Ambos cóndilos se ubican en un plano localizado más ventralmente que la cresta cnemial. Si bien no se diferencian claramente, puede inferirse que pre- sentan sección triangular. En vista dorsal, entre el cóndilo lateral y la cresta cnemial, ...
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... et al., 2008). La superficie lateral del extremo distal de la tibia tiene un surco longitudi- nal (Brusatte et al., 2008; carácter 151), el cual continúa so- bre la superficie articular distal con una escotadura localizada posterolateralmente, carácter compartido con Archosauria. El extremo distal tiene un contorno elíptico en vista distal (Fig. 12.4) y es expandida transversalmente (Brusatte et al., 2008;carácter 154). El extremo distal se encuentra levemen- te torsionado en relación al extremo proximal. En vista distal se observa el proceso articular para el astrágalo, el cual se encuentra más desarrollado ventralmente que la superficie anterior a él (Brusatte et al., ...
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... una leve torsión entre sus extremos. El trocánter anterior fibular (tubérculo para la inserción del M. iliofibularis) de la fibula se encuentra ausente (Brusatte et al., 2008; carácter 157 y Dilkes y Sues, 2009; carácter 67). En vista lateral, ocupando un tercio del largo sobre el extremo proximal de la fíbula, se observa un surco poco desarrollo (Figs. 13.2-3). Astrágalo-Calcáneo. El astrágalo está bien preservado y se encuentra completo, pero no así el calcáneo, identificándose sólo una pequeña porción en articulación con el astrágalo (Figs. 14 y 15). El astrágalo presenta una faceta tibial que ocupa gran parte de la superficie proximal del hueso. Esta faceta es subcuadrangular y se ...
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Citations
... There is a proximodistally oriented groove on the lateral surface of the distal portion (Fig. 4F). It is more pronounced in Proterochampsa barrionuevoi (Trotteyn 2011). The distal outline of the tibia is elliptical. ...
... Regarding the tibia, in CAPPA/UFSM 0293 the proximal extremity of the tibia is perpendicular in relation to its long axis, whereas in PVSJ 606 it is oblique. Moreover, in PVSJ 606, the cnemial crest is smaller than the proximal condyles (Trotteyn 2011), whereas in CAPPA/UFSM 0293 it is sub-equal in size to the proximal condyles. The fibula of PVSJ 606 maintains its anteroposterior width for most of its proximodistal length, as in other proterochampsids (although the epiphyses are slightly expanded), but in CAPPA/UFSM 0293 the fibula is significantly expanded in the proximal third of the element and then tapers distally, becoming remarkably narrow, ending in an unexpanded distal epiphysis. ...
Characterized by an elongated snout, proterochampsids are carnivorous non-archosaur archosauriforms. The clade is endemic to South America and its fossil record extends from the early Carnian to the late Carnian/early Norian. Nesting close to Archosauria, it is a key clade for understanding the origin and evolution of archosaurian traits. Unfortunately, hind limb elements are usually poorly preserved for the group. Therefore, the hind limb anatomy of proterochampsids still lacks detailed descriptions. In the present study, we partially fill this gap with the description of a new proterochampsid represented by a complete and well-preserved hind limb. Stenoscelida aurantiacus gen. et sp. nov. was excavated from the late Carnian/early Norian (Late Triassic) beds of southern Brazil. A phylogenetic investigation recovers the new taxon as a non-rhadinosuchine proterochampsid. The species bears an unusual set of traits for the group, which provides clues on the evolutionary origins of some muscle attachment structures. For instance, the femur of Stenoscelida aurantiacus gen. et sp. nov. possesses an anterior trochanter and an anterolateral scar. So far, these features have not been reported in other non-archosaurian archosauriforms. Therefore, the new specimen indicates that some typical archosaurian features evolved earlier than previously thought. The taxon also carries additional uncommon features for proterochampsids, such as an iliofibularis tubercle on the anterior margin of the fibula and a vestigial phalanx in digit V. In sum, Stenoscelida aurantiacus has one of the best-preserved hind limbs within Proterochampsidae and sheds light on the polarization of important traits regarding the evolutionary context of Archosauria.
http://zoobank.org/urn:lsid:zoobank.org:pub:C78B7CE3-AB9B-4543-833E-B2A3FEA957D9
... However, the condition of Sphodrosaurus pennsylvanicus is not unique among archosauromorphs, as it is paralleled by hyperodapedontine rhynchosaurs (e.g. Chatterjee 1974;Benton 1983) and the proterochampsian Proterochampsa barrionuevoi (Trotteyn 2011) (Figs 11D, 12A). Although Sphodrosaurus pennsylvanicus and Proterochampsa barrionuevoi are found to be closely related to each other (both as members of Proterochampsia), most phylogenetic scenarios and optimization methods indicate that the two species developed unusually broad skulls independently (e.g. ...
... As a consequence, the LDA robustly identifies the ungual of Sphodrosaurus pennsylvanicus as adapted for substrate processing (likely digging). A similar function could also be inferred for Proterochampsa barrionuevoi and other proterochampsids because of their pedal ungual morphology (see Trotteyn 2011), which is very similar to that of Sphodrosaurus pennsylvanicus. ...
... Proterochampsa barrionuevoi has been historically interpreted as a semiaquatic animal based on its cranial features (e.g. dorsally facing external nares and orbits, long rostrum, strongly ornamented external bone surfaces ;Reig 1959;Sill 1967;Romer 1971) and this hypothesis is still broadly supported (Arcucci 2011;Trotteyn 2011;Trotteyn et al. 2013). In particular, the more recent description of a fairly complete skeleton of Proterochampsa barrionuevoi has confirmed the proportionally huge size of the skull (see Results; Trotteyn 2011) and may support the semi-aquatic hypothesis. ...
Most Triassic terrestrial diapsids belong to two clades, Lepidosauromorpha or (the more diverse) Archosauromorpha. Nevertheless, the phylogenetic relationships of some Triassic diapsids have remained uncertain for decades because of the lack of preservation of phylogenetically relevant anatomical regions or because of unusual combinations of features. One of these enigmatic forms is the small-sized Sphodrosaurus pennsylvanicus from the Upper Triassic Hammer Creek Formation of the Newark Supergroup in Pennsylvania (USA). It was first identified as a procolophonid parareptile, later as a probable rhynchosaur archosauromorph, and more recently as an indeterminate neodiapsid. Here we revise the anatomy of Sphodrosaurus pennsylvanicus in order to include it for the first time in a quantitative phylogenetic analysis, which is focused on Permo–Triassic neodiapsids. Sphodrosaurus pennsylvanicus is recovered in this analysis as a doswelliid proterochampsian within Archosauromorpha. As a result, this taxon is added to the list of doswelliids known from the Carnian–Norian of the eastern and south-western USA. Previous authors recognized that the most unusual feature of Sphodrosaurus pennsylvanicus is its proportionally very large skull. Phylogenetic generalized least squares regressions confirmed that Sphodrosaurus pennsylvanicus has a larger skull than the vast majority of Permo–Triassic diapsids. Optimization in the phylogeny of the skull width to presacral length ratio shows the most likely scenario is that the extremely broad skull of Sphodrosaurus pennsylvanicus is autapomorphic, but it is not unique among archosauromorphs, being paralleled by hyperodapedontine rhynchosaurs and the proterochampsian Proterochampsa barrionuevoi. Exploration of a morphospace of linear measurements shows that Sphodrosaurus pennsylvanicus shares strong similarities with the probably semi-aquatic Proterochampsa barrionuevoi, suggesting that the former species may have had a similar mode of life. A linear discriminant analysis of ungual functional categories found that the only preserved ungual of Sphodrosaurus pennsylvanicus was suitable for digging or some other way of substrate processing.
... New discoveries have expanded the fossil record of the Early Triassic archosauromorphs from the Brazilian Sanga do Cabral Supersequence, and the phylogenetic relationships of specimens from this unit have been tested quantitatively for the first time (Pinheiro et al., 2016De-Oliveira et al., 2018. Similarly, the phylogenetic relationships of the proterochampsids are better understood now (Dilkes and Arcucci, 2012;Trotteyn andEzcurra, 2014, 2020;Ezcurra et al., 2015c;Ezcurra, 2016). Research on Brazilian hyperodapedontine rhynchosaurs has contributed to clarify their taxonomy and species-level diversity Montefeltro et al., 2010Montefeltro et al., , 2013. ...
The oldest archosauromorphs (dinosaurs, birds, crocodiles, and their stem-taxa) are recorded in middle−upper Permian rocks, but it was not after the Permo−Triassic mass extinction that the group shows a substantially high taxonomic richness and ecomorphological disparity. The early evolutionary history of the Archosauromorpha during the Early and Middle Triassic is mainly based on fossils recovered from rocks in southern Africa, Europe and Asia, whereas South America possesses a more complete fossil record of the group only in the Late Triassic. Here we revisit, discuss, and reanalyse the non-archosaurian archosauromorph fossil record of the current-day South America. The Early Triassic archosauromorph record in this continent is still scarce, but it documents the early evolution of the group in western Pangaea and is crucial to understand more globally the biotic recovery after the Permo−Triassic mass extinction. The Middle Triassic record is extremely scarce, but the Late Triassic archosauromorph assemblage of South America is among the most diverse and abundant worldwide. The last decade has witnessed a considerable improvement in our knowledge of the record, taxonomy, phylogeny, and macroevolution of the group with the input from the South American fossils. Nevertheless, a considerable amount of research is needed and ideally should be focused on some particular aspects of the Triassic evolutionary radiation of Archosauromorpha. Among them, the Early Triassic record should be expanded, more numerous and more complete Middle Triassic archosauromorph specimens are crucial to have a more complete picture of the evolution of the group, and the taxonomy of groups like proterochampsids and hyperodapedontine rhynchosaurs should be clarified through detailed anatomical work.
... The posterior portion of the facet for articulation with the coracoid is well-preserved, indicating that these two bones were not fused to each other, as occurs in specimens of Chanaresuchus bonapartei (MCZ 4035, PVL 4575), Gualosuchus reigi (PVL 4576), and Tropidosuchus romeri (PVL 4606). By contrast, the scapula and coracoid are fused to each other in specimens of Proterochampsa barrionuevoi(Trotteyn, 2011b), Pseudochampsa ischigualastensis(Trotteyn and Ezcurra, 2014), and the holotype ofGualosuchus reigi (PULR 05). The proximal end of the scapula is strongly posteriorly expanded, which results in a glenoid fossa that is placed completely posterior to the level of the scapular blade if the latter is vertically oriented. ...
The proterochampsids are crocodile-like, small- to medium-sized, quadrupedal and predatory stem-archosaurs. The rhadinosuchines are a clade of deeply nested proterochampsids that are the most abundant diapsids of the Massetognathus-Chanaresuchus Assemblage Zone of the Chañares Formation (lower Carnian) of north-western Argentina. Here, we describe two new rhadinosuchine proterochampsid specimens recently collected from the Massetognathus-Chanaresuchus Assemblage Zone of the Chañares Formation. These specimens are represented by an articulated partial skeleton and disarticulated cranial and postcranial bones, respectively. One of them is less complete, but its well-preserved disarticulated bones considerably expand the anatomical knowledge of certain regions of the rhadinosuchine skeleton. The combination of character-states present in both specimens and shared with other known rhadinosuchine species (e.g., Chanaresuchus bonapartei, Gualosuchus reigi, Rhadinosuchus gracilis) results in an unexpected increase of the morphological diversity of the group (e.g., antorbital fossa on the horizontal process of maxilla, well-exposed antorbital fossa on lacrimal, X-shaped osteoderms). We conclude that the taxonomy of the currently known rhadinosuchine specimens should be revisited, including a careful reappraisal of the intraspecific variation and the post-mortem deformation that affected the specimens in different ways.
... Over the last few years, several important contributions about the anatomy and phylogeny of proterochampsids have been published (e.g., Trotteyn 2011;Dilkes and Arcucci 2012;Trotteyn et al. 2013;Raugust et al. 2013;Trotteyn and Ezcurra 2014;Ezcurra et al. 2015), but paleobiological and paleoecological hypothesis about the group are still scarce. Aquatic or amphibious lifestyles were traditionally accepted for proterochampsians based on convergent/homoplasic characters with extant crocodiles, but this has not been rigorously tested. ...
Proterochampsians are a South American endemic group of non-archosaurian archosauriforms with morphological characteristics recollecting Recent crocodilians, and therefore have been proposed as aquatic species. However, this has not been based on careful examination of anatomical and histological features. We provide a review of the morphological and histological evidence present in the skeleton of proterochampsids and discuss its implications for inferring the lifestyles of these organisms. Anatomical features such as a secondary palate, marginal dentition, palatine teeth, morphology of the tail, limb modification, and dermal armor are reviewed, and details of histological structures are described based on bone thin sections. Histological examination reveals a predominance of fibrolamellar bone tissue, suggesting rapid periosteal osteogenesis and therefore overall fast bone growth. The existence of discontinuities (LAGs) demonstrates that these animals responded to changes in their environment. Ecomorphological features do not provide definitive evidence for the lifestyles of proterochampsids, but allow us to propose a terrestrial/amphibious condition. The same is true of the histological features, particularly compactness of the bone.
... In many respects, the femur (and also the equivocally referred tibiae and ulnae) is strikingly similar to that of euparkeriids such as Euparkeria capensis and Dorosuchus neoetus (see Ewer 1965;Sennikov 1989aSennikov , 1989bSookias and Butler 2013;Sookias et al. 2014). However, there is a fundamental difference between Dongusuchus efremovi and these taxa: the femur (and other equivocally referred long bones) is much more slender and gracile (see description) than those of euparkeriids and many other non-crown archosauriforms (see Gower 2003;Borsuk-Białynicka and Sennikov 2009;Nesbitt, Stocker, et al. 2009;Nesbitt 2011;Trotteyn 2011;Ezcurra et al. 2013;Sues et al. 2013). ...
European Russia has yielded several fragmentary but potentially important archosauriform specimens from the Middle Triassic, but these have been only briefly described in the literature. One of these puzzling taxa is Dongusuchus efremovi Sennikov, 1988, described from the Donguz Svita. We present a redescription of Dongusuchus efremovi, which includes the first photographic atlas and thorough anatomical description of the holotype and referred specimens. This taxon is shown to be a gracile, probably fast-running species with elongate and slender limbs. A phylogenetic analysis recovers Dongusuchus efremovi as an early-diverging, non-archosaurian archosauriform. Previous work had suggested that this taxon was a ‘rauisuchid’. The gracile proportions of the femur and somewhat wedge-shaped head, however, are unusual for basal archosauriforms and are similar to the plesiomorphic state in crocodile and avian-line crown archosaurs. Several Early-Middle Triassic basal archosauriforms and early members of the crocodile and avian lineages were gracile with elongate, slender limbs. This suggests that the limb morphology of Dongusuchus efremovi may be plesiomorphic for Archosauria and proximal clades.
... Triassic pterosaurs have dicephalous ribs with distinct but short tuberculum and a long capitulum and a somewhat curved shaft, at least in the mid-proximal dorsals ( [32]: Plates 2, 8, 12 and 14, Figures 11a and 33). However, many other diapsids bear dicephalous dorsal ribs, including some protorosaurians, other basal archosauromorphs such as rhynchosaurs [35] and trilophosaurs [36], most basal archosauriforms (e.g., Euparkeria [37], Proterochampsa [38], 'Proterosuchia' [39], and Vancleavea [40]), most basal archosaurs [41][42][43], and dinosauromorphs [44][45]. ...
A small accumulation of bones from the Norian (Upper Triassic) of the Seazza Brook Valley (Carnic Prealps, Northern Italy) was originally (1989) identified as a gastric pellet made of pterosaur skeletal elements. The specimen has been reported in literature as one of the very few cases of gastric ejecta containing pterosaur bones since then. However, the detailed analysis of the bones preserved in the pellet, their study by X-ray microCT, and the comparison with those of basal pterosaurs do not support a referral to the Pterosauria. Comparison with the osteology of a large sample of Middle-Late Triassic reptiles shows some affinity with the protorosaurians, mainly with Langobardisaurus pandolfii that was found in the same formation as the pellet. However, differences with this species suggest that the bones belong to a similar but distinct taxon. The interpretation as a gastric pellet is confirmed.
... The fossil record of the group is currently restricted to eight nominal species from the Middle and Late Triassic Ischigualasto-Villa Unión and Paraná basins of northwestern Argentina and southern Brazil, respectively (Reig, 1959;Romer, 1971;Kischlat, 2000;Dilkes and Arcucci, 2012;Trotteyn et al., 2013). Several papers have improved our anatomical and phylogenetic knowledge of proterochampsids in the last few years (e.g., Trotteyn andHaro, 2011, 2012;Trotteyn, 2011;Dilkes and Arcucci, 2012;Trotteyn et al., , 2013Raugust et al., 2013;Trotteyn and Ezcurra, 2014), but there are still some poorly known species that constitute a gap in the knowledge of the group. One of these poorly known species is Rhadinosuchus gracilis Huene, 1938, from the early Late Triassic Santa Maria Sequence 2 of southern Brazil (Fig. 1). ...
... The fossil record of the group is currently restricted to eight nominal species from the Middle and Late Triassic Ischigualasto-Villa Unión and Paraná basins of northwestern Argentina and southern Brazil, respectively (Reig, 1959;Romer, 1971;Kischlat, 2000;Dilkes and Arcucci, 2012;Trotteyn et al., 2013). Several papers have improved our anatomical and phylogenetic knowledge of proterochampsids in the last few years (e.g., Trotteyn andHaro, 2011, 2012;Trotteyn, 2011;Dilkes and Arcucci, 2012;Trotteyn et al., , 2013Raugust et al., 2013;Trotteyn and Ezcurra, 2014), but there are still some poorly known species that constitute a gap in the knowledge of the group. One of these poorly known species is Rhadinosuchus gracilis Huene, 1938, from the early Late Triassic Santa Maria Sequence 2 of southern Brazil (Fig. 1). ...
... The gastralia are rod-like and at least some of them are gently curved posteriorly, as also occurs in the middle dorsal region of the gastral basket of Proterosuchus alexanderi (Hoffman, 1965) (NM QR 1484). One of the gastralia seems to have an anteroposteriorly expanded and plate-like end, resembling the condition in Proterochampsa barrionuevoi (Trotteyn, 2011). ...
The proterochampsids are small to medium-sized, quadrupedal and probable semi-aquatic reptiles that were part of the evolutionary radiation of Archosauromorpha during the Triassic. The group is restricted to the Middle and Late Triassic of South America with eight nominal species. Rhadinosuchus gracilis Huene was the first described proterochampsid and comes from the late Carnian—earliest Norian of southern Brazil. This genus and species is currently the most enigmatic and poorly known member of the group. For this reason we redescribe here its anatomy and discuss its phylogenetic relationships. We found that this species can be distinguished from other proterochampsids and we dismiss the proposed synonymy with Cerritosaurus binsfeldi Price. Our quantitative phylogenetic analysis found Rhadinosuchus gracilis more closely related to Gualosuchus reigi Romer and Chanaresuchus bonapartei Romer than to other proterochampsids, together forming the subfamily Rhadinosuchinae. Characters supporting this assignment include a maxilla with a distinct longitudinal change in slope between lateral and dorsal surfaces, and dorsal surface of nasal and frontal ornamented by ridges showing a radial pattern. In addition, Rhadinosuchus gracilis was recognized as the sister taxon of Chanaresuchus bonapartei based on a lacrimal with an antorbital fossa that occupies almost half or more of the anteroposterior length of the ventral process. The topology of the phylogenetic analysis shows that the Brazilian species do not form a monophyletic clade and favours multiple dispersal events between the Ischigualasto-Villa Unión (northwestern Argentina) and the Paraná (southern Brazil) basins.
... The skull length represents approximately 0.8 times the length of the presacral vertebral series (Fig. 1), resembling the condition in Tropidosuchus romeri (PVL 4601). By contrast, the skull is proportionally larger with respect to its postcranium in Proterochampsa barrionuevoi [27]. The neck of Pseudochampsa ischigualastensis is proportionally short, representing approximately half of the length of the dorsal series. ...
... Humerus with low deltopectoral crest. The humeri of 'Chanaresuchus' ischigualastensis, Chanaresuchus bonapartei (MCZ 4035), Gualosuchus reigi (PVL 4576) and Tropidosuchus romeri (PVL 4601) possess a low deltopectoral crest, contrasting with the condition in Proterochampsa barrionuevoi [27]. The condition of this character is unknown in Rhadinosuchus gracilis. ...
Proterochampsids are crocodile-like, probably semi-aquatic, quadrupedal archosauriforms characterized by an elongated and dorsoventrally low skull. The group is endemic from the Middle-Late Triassic of South America. The most
recently erected proterochampsid species is ‘‘Chanaresuchus ischigualastensis’’,
based on a single, fairly complete skeleton from the early Late Triassic
Ischigualasto Formation of northwestern Argentina. We describe here in detail the non-braincase cranial and postcranial anatomy of this species and revisit its
taxonomy and phylogenetic relationships. The phylogenetic analysis recovered
‘Chanaresuchus ischigualastensis’ as part of a trichotomy together with
Gualosuchus reigi and Chanaresuchus bonapartei. Accordingly, ‘‘Chanaresuchus ischigualastensis’’ can be potentially more closely related to Gualosuchus reigi, or even Rhadinosuchus gracilis, than to Chanaresuchus bonapartei. In addition, after discussing previously claimed synapomorphies of Chanaresuchus, we could not
find unambiguous support for the monophyly of the genus. As a result, we propose here the erection of the new genus Pseudochampsa for ‘Chanaresuchus ischigualastensis’, which results in the new combination Pseudochampsa ischigualastensis. The information provided here about the anatomy and taxonomy
of Pseudochampsa ischiguaslastensis will be useful for future quantitative analyses focused on the biogeography and macroevolutionary history of proterochampsids.
... The skull length represents approximately 0.8 times the length of the presacral vertebral series (Fig. 1), resembling the condition in Tropidosuchus romeri (PVL 4601). By contrast, the skull is proportionally larger with respect to its postcranium in Proterochampsa barrionuevoi [27]. The neck of Pseudochampsa ischigualastensis is proportionally short, representing approximately half of the length of the dorsal series. ...
... Humerus with low deltopectoral crest. The humeri of 'Chanaresuchus' ischigualastensis, Chanaresuchus bonapartei (MCZ 4035), Gualosuchus reigi (PVL 4576) and Tropidosuchus romeri (PVL 4601) possess a low deltopectoral crest, contrasting with the condition in Proterochampsa barrionuevoi [27]. The condition of this character is unknown in Rhadinosuchus gracilis. ...
Proterochampsids are crocodile-like, probably semi-aquatic, quadrupedal archosauriforms characterized by an elongated and dorsoventrally low skull. The group is endemic from the Middle-Late Triassic of South America. The most recently erected proterochampsid species is "Chanaresuchus ischigualastensis", based on a single, fairly complete skeleton from the early Late Triassic Ischigualasto Formation of northwestern Argentina. We describe here in detail the non-braincase cranial and postcranial anatomy of this species and revisit its taxonomy and phylogenetic relationships. The phylogenetic analysis recovered 'Chanaresuchus ischigualastensis' as part of a trichotomy together with Gualosuchus reigi and Chanaresuchus bonapartei. Accordingly, "Chanaresuchus ischigualastensis" can be potentially more closely related to Gualosuchus reigi, or even Rhadinosuchus gracilis, than to Chanaresuchus bonapartei. In addition, after discussing previously claimed synapomorphies of Chanaresuchus, we could not find unambiguous support for the monophyly of the genus. As a result, we propose here the erection of the new genus Pseudochampsa for 'Chanaresuchus ischigualastensis', which results in the new combination Pseudochampsa ischigualastensis. The information provided here about the anatomy and taxonomy of Pseudochampsa ischiguaslastensis will be useful for future quantitative analyses focused on the biogeography and macroevolutionary history of proterochampsids.
