Cranial Anatomy and Dentition of the Aetosaur <i>Typothorax Coccinarum</i> (Archosauria: Pseudosuchia) from the Upper Triassic (Revueltian–Mid Norian) Chinle Formation of Arizona

Reyes, William A; Parker, William G.; Marsh, Adam D.

doi:10.1080/02724634.2020.1876080

Cited by 11 publications

(59 citation statements)

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“…The preserved antorbital region represents more than half of the skull length, consistent with other known specimens of Aetosauroides scagliai (PVL 2059 and UFSM 11505) and other aetosaurs. The nares are anteroposteriorly elongated, as in other non-aetosaurine aetosaurs (see Reyes et al, 2021). The antorbital fenestra is anteroposteriorly elongate and dorsoventrally short (being four times longer than tall).…”

Section: Descriptionmentioning

confidence: 76%

“…Calyptosuchus wellesi (UCMP 78695 and UCMP 195192), as well as the gracilisuchid Gracilisuchus stipanicicorum Romer, 1972 (MCZ 4116 and MCZ 4117). This contrasts with the concave maxilla of most other pseudosuchians (e.g., Mastrantonio et al, 2019), including aetosaurs such as Typothorax coccinarum (according to Heckert and Lucas, 2010;Reyes et al, 2021), Longosuchus meadei (TMM 31185-84), Desmatosuchus smalli (TTUP 9024), Stagonolepis robertsoni (NMS R4787; Walker, 1961), and Stagonolepis olenkae (e.g., ZPAL AbIII 1996 and1997;Sulej, 2010). As in A. ferratus and P. andressorum (Schoch and Desojo, 2016), the posterior region of the maxilla of MCN-PV 2347 is constricted prior its end, which is also the case of UFSM 11505 (better observed in the left element).…”

Section: ) or Stagonolepis Olenkaementioning

confidence: 82%

“…(which is edentulous; Small, 2002), Stenomyti huangae (which has three premaxillary teeth; , Typothorax coccinarum Cope, 1874 (five;Reyes et al, 2021), both Stagonolepis species (four to five; Walker, 1961;Sulej, 2010), and ornithosuchids (three;von Baczko and Desojo, 2016).…”

Section: Descriptionmentioning

confidence: 99%

“…Recent research on A. scagliai has provided a better understanding of its intraspecific variation Taborda et al, 2013;Taborda et al, 2015;Paes Neto et al, 2021b) and cranial osteology (Brust et al, 2018;Paes Neto et al, 2021a). These and other studies (e.g., Desojo, 2005) have firmly established the Gondwanan A. scagliai as a valid taxon, distinct from the Laurasian S. robertsoni and Calyptosuchus wellesi Ballew, 1985 (contra Heckert andLucas, 2000;Lucas and Heckert, 2001;Heckert and Lucas, 2002), a status recognized in most recent work on the group (e.g., Desojo et al, 2012Desojo et al, , 2013Robertoda-Silva et al, 2014;Heckert et al, 2015;Parker, 2016a,b;Schoch and Desojo, 2016;Ezcurra et al, 2017;Brust et al, 2018;Hoffman et al, 2018;Parker, 2018a,b;Desojo et al, 2020a,b;Marsh et al, 2020;Czepiński et al, 2021;Reyes et al, 2021).…”

Section: Introductionmentioning

confidence: 98%

“…However, the latter species was recently reinterpreted as a junior synonym of A. scagliai, with apparent differences being attributable to the immature state of the holotype (Paes Neto et al, 2021b). In phylogenetic analyses, A. scagliai has been recovered as either the sister-taxon of Stagonolepis robertsoni Agassiz, 1844(e.g., Parrish, 1994Heckert et al, 1996;Heckert and Lucas, 1999;Harris et al, 2003;Parker, 2007) or as the earliest-diverging aetosaur (i.e., the only non-stagonolepidid aetosaur; e.g., Desojo et al, 2012;Heckert et al, 2015;Schoch and Desojo, 2016;Parker, 2016a;Brust et al, 2018;Hoffman et al, 2018;Reyes et al, 2021). Recent research on A. scagliai has provided a better understanding of its intraspecific variation Taborda et al, 2013;Taborda et al, 2015;Paes Neto et al, 2021b) and cranial osteology (Brust et al, 2018;Paes Neto et al, 2021a).…”

Section: Introductionmentioning

confidence: 99%

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Skull osteology of Aetosauroides scagliai Casamiquela, 1960 (Archosauria: Aetosauria) from the Late Triassic of Brazil: New insights into the paleobiology of aetosaurs

Neto

Desojo²,

Brust³

et al. 2021

Palaeontol Electron

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Aetosauroides scagliai, from the Ischigualasto Formation of Argentina and Santa Maria Supersequence of Brazil (Carnian-Norian), is one of the oldest members of Aetosauria, a diverse clade of armored crocodile-line archosaurs. Aetosauroides scagliai differs from other aetosaurs in having the maxilla excluded from the margin of the external nares, the length/width ratio of the postzygapophyses ≤ 0.75, and other features that place it as one of the earliest-diverging members of the clade. In this paper we provide a detailed description of the skull of A. scagliai based on a new Brazilian specimen, revealing that it lacks a pneumatic cavity on the medial surface of the maxilla and further differs from all other known aetosaurs by the presence of ≥ 12 dentary teeth. However, contra previous studies, the elongated posterior process of the jugal does articulate ventrally with the quadratojugal in A. scagliai, forming the posteroventral corner of the skull as in all other aetosaurs. Aetosauroides scagliai exhibits some characters typical of predatory archosaurs (like the recurved ziphodont teeth and mandibular articulation at the level of the tooth row), but was probably an omnivore, as it also shares several probable adaptations for herbivory with aetosaurs generally (i.e., edentulous anterior premaxilla and dentary) and stagonolepidoids specifically (e.g., shovel-shaped snout). This suggests that there was greater trophic diversity in this clade than usually recognized, at least early in their evolutionary history.

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Section: Descriptionmentioning

confidence: 76%

Section: ) or Stagonolepis Olenkaementioning

confidence: 82%

Section: Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Skull osteology of Aetosauroides scagliai Casamiquela, 1960 (Archosauria: Aetosauria) from the Late Triassic of Brazil: New insights into the paleobiology of aetosaurs

Neto

Desojo²,

Brust³

et al. 2021

Palaeontol Electron

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Osteology and relationships of Revueltosaurus callenderi (Archosauria: Suchia) from the Upper Triassic (Norian) Chinle Formation of Petrified Forest National Park, Arizona, United States

Parker

Nesbitt

Irmis

et al. 2021

The Anatomical Record

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Once known solely from dental material and thought to represent an early ornithischian dinosaur, the early‐diverging pseudosuchian Revueltosaurus callenderi is described from a minimum of 12 skeletons from a monodominant bonebed in the upper part of the Chinle Formation of Arizona. This material includes nearly the entire skeleton and possesses a combination of plesiomorphic and derived character states that help clarify ingroup relationships within Pseudosuchia. A phylogenetic analysis recovers R. callenderi in a clade with Aetosauria and Acaenasuchus geoffreyi that is named Aetosauriformes. Key autapomorphies of R. callenderi include a skull that is longer than the femur, a complete carapace of dermal armor including paramedian and lateral rows, as well as ventral osteoderms, and a tail end sheathed in bone. Histology of the femur and associated osteoderms demonstrate that R. callenderi was slow growing and that the individuals from the bonebed were not young juveniles but had not ceased growing. A review of other material assigned to Revueltosaurus concludes that the genus cannot be adequately diagnosed based on the type materials of the three assigned species and that only R. callenderi can be confidently referred to Revueltosaurus.

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New digital braincase endocasts of two species of Desmatosuchus and neurocranial diversity within Aetosauria (Archosauria: Pseudosuchia)

Baczko

Desojo

Gower

et al. 2021

The Anatomical Record

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In the present contribution we revise, figure, and redescribe several isolated braincases of the iconic aetosaur Desmatosuchus from the Placerias Quarry locality, Chinle Formation, Arizona, United States. The detailed study of the isolated braincases from the UCMP collection allowed us to assign them at the species-level and recognize two species of Desmatosuchus for the Placerias Quarry: D. spurensis and D. smalli. The former can be distinguished from the latter by the presence of a transverse sulcus on the parietals, deep median pharyngeal recess on the basisphenoid, almost no gap between the basal tubera and the basipterygoid processes, and the exoccipitals meeting at the midline. The presence of D. smalli at the Placerias Quarry has not been previously reported. Based on the braincases UCMP 27408, 27410, 27407, three new brain endocasts were developed through CT scan images, reconstructing the most complete endocranial casts known for an aetosaur, including the encephalon, cranial nerves, inner ear, and endocranial vasculature. The cranial endocasts also exhibited some differences between both species of Desmatosuchus, with D. spurensis having a distinguishable dural expansion and markedly asymmetric anterior and posterior semicircular canals of the labyrinth. Additionally, the combination of osteological features and the endocranial casts allowed us to identify and discuss the presence of an ossified orbitosphenoid on the anteriormost region of the braincase among aetosaurs. Furthermore, we were able to reinterpret some of the observations made by previous authors on the endocast of the holotype of Desmatosuchus spurensis (UMMP VP 7476) and provide some insight into their neurosensory capabilities.

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Cranial Anatomy and Dentition of the Aetosaur Typothorax Coccinarum (Archosauria: Pseudosuchia) from the Upper Triassic (Revueltian–Mid Norian) Chinle Formation of Arizona

Cited by 11 publications

References 42 publications

Skull osteology of Aetosauroides scagliai Casamiquela, 1960 (Archosauria: Aetosauria) from the Late Triassic of Brazil: New insights into the paleobiology of aetosaurs

Skull osteology of Aetosauroides scagliai Casamiquela, 1960 (Archosauria: Aetosauria) from the Late Triassic of Brazil: New insights into the paleobiology of aetosaurs

Osteology and relationships of Revueltosaurus callenderi (Archosauria: Suchia) from the Upper Triassic (Norian) Chinle Formation of Petrified Forest National Park, Arizona, United States

New digital braincase endocasts of two species of Desmatosuchus and neurocranial diversity within Aetosauria (Archosauria: Pseudosuchia)

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