[Paleontology • 2026] Austronaga minuta • Highly aquatic marine stem Archosaur with soft tissue preservation

Austronaga minuta Wang, Lei & Li, 2023

 

in Wang, Fraser, Spiekman, Z. Li, et C. Li, 2026. 

DOI: doi.org/10.1126/sciadv.aeb7528 

Artwork by Gabriel Ugueto

 

Abstract

Archosauromorpha is a dominant reptile clade that primarily occupied terrestrial ecosystems with limited secondarily aquatic invasions that are poorly known. Here we report on a well-preserved Triassic reptile representing the earliest stem-archosaur to evolve unequivocal aquatic specializations. This taxon exhibits a suite of aquatic adaptations previously unknown in stem-archosaurs, such as hyperphalangy, enhanced paddle-like forelimbs, and a loss of articulation between the sacrum and pelvis, indicating an advanced aquatic lifestyle. The fossil exhibits the oldest known stomach, liver, and intestinal preservations in reptiles. Our findings provide unexpected insights into the early aquatic diversification of Archosauromorpha during the Triassic marine ecosystem recovery and highlight a conservative gastrointestinal system in an early Mesozoic vertebrate. In the absence of clear terrestrial members of the other major Mesozoic marine reptile lineages (e.g., ichthyosaurs and sauropterygians), this discovery provides an unambiguous example of such a lineage including both decidedly terrestrial and extensively marine forms, providing tantalizing evidence for the land-to-sea transition in Triassic reptiles.

Systematic paleontology

Diapsida, Osborn, 1903.

Archosauromorpha, von Huene, 1946.

Tanysauria, Spiekman et al., 2024.

Trachelosauridae, Abel 1919 (sensu Spiekman et al., 2024).

Skeleton of the holotype of Austronaga minuta (IVPP V18579). Abbreviations are in the Supplementary Materials. Scale bars, 2 cm (A) and 1 cm (B to D).

Austronaga minuta, Wang et al., 2023.

Type specimen: Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) V18579, a complete articulated skeleton preserved on two slabs (Fig. 1).

Locality and horizon: Waina Village, Luoping County, Yunnan Province, China; Member II of Guanling Formation, middle Anisian (Pelsonian), Middle Triassic.

Emended diagnosis: A tanysaur with the following features: quadrate anteroposteriorly broad and plate-like in lateral view with concave posterior margin; 18 cervical, 24 dorsal vertebrae; tall axe-shaped neural spine on axis; cervical neural spines prominent, with convex dorsal margin and without anterodorsal or posterodorsal projections; chevrons of mid-caudal region hatchet-shaped, with prominent distal expansion and a notch at the midpoint of its ventral margin; forelimb distinctly longer than hindlimb with humerus to femur length ratio over two; hyperphalangy present in both manus and pes.

Reconstruction of the long-necked marine reptile Austronaga minuta.

Artwork by Gabriel Ugueto

Wei Wang, Nicholas C. Fraser, Stephan N. F. Spiekman, Zhiheng Li, Olivier Rieppel, Hong Lei, Torsten M. Scheyer and Chun Li. 2026. Highly aquatic marine stem Archosaur with soft tissue preservation. Science Advances. 12(31); DOI: doi.org/10.1126/sciadv.aeb7528 [29 Jul 2026]

[Paleontology • 2026] Isodapedon varzealis • A New hyperodapedontine rhynchosaur (Archosauromorpha: Rhynchosauria) from a Cynodont-dominated Site (Upper Triassic) of southern Brazil

 

Isodapedon varzealis  

Schiefelbein, Garcia, Doering & Müller, 2026

DOI: doi.org/10.1098/rsos.260176 

Artwork by Caio Fantini.

 

Abstract

We describe Isodapedon varzealis gen. et sp. nov., a new hyperodapedontine rhynchosaur from the Carnian deposits of the Candelária Sequence, southern Brazil. Phylogenetic analyses place this taxon outside known South American hyperodapedontines, including Macrocephalosaurus mariensis and ‘Hyperodapedon’ species, and support the restriction of the genus Hyperodapedon to its type species, thereby revealing greater diversity within the group than previously recognized. Isodapedon varzealis gen. et sp. nov. is characterized by symmetrical maxillary tooth bearing areas and distinctive dentary morphology, indicating divergent feeding adaptations relative to known rhynchosaurs. Stratigraphic occurrence in beds correlated with the Exaeretodon sub-zone of the Hyperodapedon Assemblage Zone, and its phylogenetic affinities with early diverging hyperodapedontines from Argentina and Scotland, imply a geographically widespread radiation of conservative morphotypes across southwestern Gondwana. This study highlights the complexity of Late Triassic rhynchosaur evolution and underscores the importance of continued palaeontological investigation in refining the taxonomy, biostratigraphy and palaeoecology of this key herbivorous clade.

Keywords: Rhynchosauria, Late Triassic, Candelária Sequence, Archosauromorpha

Subjects:palaeontology

Geological context of the Várzea do Agudo site and provenance of CAPPA/UFSM 0371. (A) Geologic map of the central region of Rio Grande do Sul (southern Brazil) showing the surface distribution of stratigraphic units of the Paraná Basin. (B) Field photograph of the Várzea do Agudo site. (C) Stratigraphic column of the Várzea do Agudo site depicting its fossiliferous content distribution. (D) Life reconstruction of CAPPA/UFSM 0371 by Caio Fantini. (E) Tridimensional model of the partial cranium of CAPPA/UFSM 0371 in right lateral view.

Abbreviations: cs, coarse-sandstone; Fm, formation; fs, fine-sandstone; g, gravel-sandstone; m, mudstone; ms, medium-sandstone. Silhouettes based on artwork by Caio Fantini and Felipe Elias.

Skull and lower jaws of Isodapedon varzealis gen. et sp. nov. (CAPPA/UFSM 0371).
(A) photographs, interpretative illustration and three-dimensional model from surface scan of the skull of CAPPA/UFSM 0371 in right lateral view. (B) Photographs, interpretative illustration and three-dimensional model from surface scan of the skull of CAPPA/UFSM 0371 in left lateral view.

Abbreviations: a, angular; aoc, anguli oris crest; d, dentary; jug, jugal; max, maxilla; mf, mental foramen; pmx l, left premaxilla; pmx r, right premaxilla; sa, surangular; sp, splenial. Black arrow points anteriorly.

Isodapedon varzealis gen. et sp. nov. craniomandibular elements.
 (A) Left skull in lateral view of Isodapedon varzealis gen. et sp. nov. (CAPPA/UFSM 0371) with emphasis on maxillary dentition area (occlusal view). (B) Left lower jaw in medial view with emphasis on lingual dentition area (oblique occlusal view).

Abbreviations: dg, diagonal gaps; lbt, labial teeth; lgt, lingual teeth; ls, longitudinal sulcus; sg, shallow groove; sms, short medial shelf. Black arrow points anteriorly.

Archosauromorpha 

Rhynchosauria  

Rhynchosauridae 

Hyperodapedontinae 

Isodapedon gen. nov.

Type and only species: Isodapedon varzealis sp. nov.

Etymology. The genus name is derived from the Ancient Greek ἴσος (ísos), meaning ‘equal’ or ‘the same’, as a reference to the equally wide tooth-bearing areas of the maxilla.

Isodapedon varzealis sp. nov.

Etymology. The species name refers to the locality of ‘Várzea do Agudo’ in which the specimen was collected.

Diagnosis. The holotype of Isodapedon varzealis is distinguished from all other known rhynchosaurids by the following unique combination of morphological traits (* asterisk denotes autapomorphies): maxilla divided into two tooth-bearing areas by a single longitudinal sulcus; equally wide maxillary lateral and medial tooth-bearing areas; same number (three) of longitudinal rows of teeth in both maxillary lateral and medial tooth-bearing areas; absence of lingual teeth in the medial surface of the maxilla; straight posterior margin of the parietal; sharp sagittal crest extending up to the posterior margin of the parietal; short and rounded ventral process of the squamosal; distinct posterior process in the squamosal; no contact between the lacrimal and palatine; ‘blunt’ and greatly reduced posteroventral process of the dentary; single dorsal blade in the dentary; medial shelf in the medial surface of the posterior portion of the dentary that does not reach half the length of the bone*; medial shelf separated from the dorsal blade of the dentary by a shallow groove; dorsal margin of the posterior portion of the dorsal blade extending markedly further dorsally than the posterior portion of the medial shelf at the level of the posteriormost lingual tooth; and single well-defined row of small, dorsally projected, closely packed lingual teeth in the dentary.

Artistic representation of a Late Triassic landscape of southern Brazil depicting individuals of Isodapedon varzealis gen. et sp. nov. in the foreground and a proterochampsid in the background.

Artwork by Caio Fantini.

 

Jeung Hee Schiefelbein; Maurício Silva Garcia; Mariana Doering and Rodrigo Temp Müller. 2026. A New hyperodapedontine rhynchosaur from a Cynodont-dominated Site (Upper Triassic) of southern Brazil. R Soc Open Sci. 13(4); 260176. DOI: doi.org/10.1098/rsos.260176 [15 Apr 2026]

[Paleontology • 2024] Dinocephalosaurus orientalis Li, 2003: A remarkable marine archosauromorph (Diapsida: Archosauromorpha) from the Middle Triassic of southwestern China

 

Dinocephalosaurus orientalis Li, 2003

Restoration of Dinocephalosaurus orientalis depicted among a shoal of the large, predatory actinopterygian fish, Saurichthys.

in Spiekman, Wang, Zhao, et al., 2024. 

DOI: 10.1017/S175569102400001X

Artwork by Marlene Donnelly.

 

Abstract

The non-archosauriform archosauromorph Dinocephalosaurus orientalis was first described from the Upper Member of the Guanling Formation (late Anisian, Middle Triassic) of Guizhou Province by Li in 2003 on the basis of a complete articulated skull and the first three cervical vertebrae exposed in dorsal to right lateral view. Since then, additional specimens have been discovered in southwestern China. Here, five newly discovered specimens are described for the first time, and redescriptions of the holotype IVPP V13767 and another referred specimen, IVPP V13898, are provided. Together, these permit the description of the complete skeleton of this remarkable long-necked marine reptile. The postcranial skeleton is as much as 6 metres long, and characterised by its long tail and even longer neck. The appendicular skeleton exhibits a high degree of skeletal paedomorphosis recalling that of many sauropterygians, but the skull and neck are completely inconsistent with sauropterygian affinities. The palate does not extend back over the basisphenoid region and lacks any development of the closed condition typical of sauropterygians. The arrangement of cranial elements, including the presence of narial fossae, is very similar to that seen in another long-necked archosauromorph, Tanystropheus hydroides, which at least in part represents a convergence related to an aquatic piscivorous lifestyle. The long and low cervical vertebrae support exceptionally elongate cervical ribs that extend across multiple intervertebral joints and contribute to a ‘stiffening bundle of ribs’ extending along the entire ventral side of the neck, as in many other non-crocopodan archosauromorphs. The functional significance of the extraordinarily elongate neck is hard to discern but it presumably played a key role in feeding, and it is probably analogous to the elongate necks seen in pelagic, long-necked plesiosaurs. Dinocephalosaurus orientalis was almost certainly a fully marine reptile and even gave birth at sea.

Keywords: late Anisian, marine reptile, non-archosauriform, southern China,   

Diapsida Osborn, 1903

Archosauromorpha von Huene, 1946

Dinocephalosauridae Spiekman et al. , 2021

Dinocephalosaurus Li, 2003

Type species: Dinocephalosaurus orientalis Li,2003. 

Distribution: Upper Member of the Guanling Formation (late Anisian, Middle Triassic) near Xinmin in Panxian County, southwestern Guizhou Province, and in Luoping County, eastern Yunnan Province, P.R. China.

Dinocephalosaurus orientalis Li, 2003

Type locality: Xinmin, Panxian County, Guizhou Province, southwestern China.

Horizon: Upper Member of Guanling Formation, Pelsonian, Anisian, Middle Triassic.

 Restoration of Dinocephalosaurus orientalis depicted among a shoal of the large, predatory actinopterygian fish, Saurichthys.

Artwork by Marlene Donnelly.

Summary: 

The Middle Triassic (latest Anisian) marine reptile Dinocephalosaurus orientalis is fully described in detail on the basis of seven beautifully preserved specimens from southwestern Guizhou Province, southern China, five of which are presented for the first time. Characters in the skull and neck are consistent with Dinocephalosaurus orientalis being included within Archosauromorpha. With 32, mostly elongate, cervical vertebrae, it had an extraordinarily long neck that draws comparison with the neck of Tanystropheus hydroides, another aquatic non-crocopodan archosauromorph that has been recorded from the Middle Triassic of both Europe and China. Both taxa share several other cranial features, including a fish-trap type dentition, a distinct antorbital recess and a wide palatal ramus of the pterygoid. The phylogenetic placement of Dinocephalosaurus orientalis is hampered by high levels of homoplasy, but our analysis suggests that the similarities between Dinocephalosaurus orientalis and Tanystropheus hydroides are largely convergent. Instead, the results corroborate the presence of a monophyletic Dinocephalosauridae outside Tanystropheidae. A greater expression of paedomorphosis in the appendicular skeleton and the presence of paddle-shaped autopodia in Dinocephalosaurus orientalis also suggest an adaptation to more open waters than in Tanystropheus hydroides. Dinocephalosaurus orientalis and Tanystropheus sp. were not contemporaries in the eastern Tethys based on current fossil occurrences: all finds of Tanystropheus sp. to date being from latest Ladinian or earliest Carnian sequences. The exact function of the extraordinary long neck of Dinocephalosaurus orientalis is unclear but it almost certainly aided in catching fish, which are preserved in the stomach contents of one of the specimens.

Stephan N.F. SPIEKMAN, Wei WANG, Lijun ZHAO, Olivier RIEPPEL, Nicholas C. FRASER and Chun LI. 2024. Dinocephalosaurus orientalis Li, 2003: A remarkable marine archosauromorph from the Middle Triassic of southwestern China. Earth and Environmental Science Transactions of The Royal Society of Edinburgh. First View; 1 - 33. DOI: 10.1017/S175569102400001X

[Paleontology • 2024] The Redescription of Malerisaurus robinsonae (Archosauromorpha: Allokotosauria) from the Upper Triassic lower Maleri Formation, Pranhita-Godavari Basin, India

 

Malerisaurus robinsonae   

in Sengupta, Ezcurra et Bandyopadhyay, 2024. 

DOI: 10.1002/ar.25392  

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Abstract

Allokotosauria, a clade of non-archosauriform archosauromorphs with a broad diversity of body plans, plays a crucial role in better understanding the evolutionary history of early diverging stem-archosaurs. Here we provide a detailed redescription of Malerisaurus robinsonae, a malerisaurine allokotosaur from the middle Carnian—lowermost Norian lower Maleri Formation, Pranhita-Godavari Basin, India. The new anatomical information available from recently discovered and well-preserved skeletons of various allokotosaurs, such as Azendohsaurus madagaskarensis, Shringasaurus indicus, Puercosuchus traverorum, and Malerisaurus-like taxa, and their comparison with Malerisaurus robinsonae enriches our understanding of the anatomy of this species. To reassess the phylogenetic relationships of Malerisaurus robinsonae, we revised its scorings and included eight additional allokotosaurian species to the already most comprehensive phylogenetic dataset focused on Permo-Triassic archosauromorphs. We modified 70 scorings for Malerisaurus robinsonae and the new analysis recovered this species at the base of Malerisaurinae and this group as the earliest branch of Azendohsauridae. Pamelaria dolichotrachela is found as the earliest diverging non-malerisaurine azendohsaurid and sister taxon to the Shringasaurus indicus + Azendohsaurus spp. clade. Trilophosaurid interrelationships are well resolved, with Teraterpeton hrynewichorum, Coelodontognathus ricovi, and Rutiotomodon tytthos as their successive earliest-branching species. The position of Anisodontosaurus greeri as a sister taxon to Variodens inopinatus bolsters long ghost lineages in the Late Triassic trilophosaurid record. A disparity analysis of tooth crown morphology shows that Allokotosauria is the most disparate Permo-Triassic archosauromorph clade, exploring the almost complete range of basic crown morphologies. Trilophosaurids occupy an area of the dental morphospace unique among archosauromorphs.

Keywords: Allokotosaur Gondwana India Malerisaurine Triassic

 

Saradee Sengupta, Martín D. Ezcurra and Saswati Bandyopadhyay. 2024. The Redescription of Malerisaurus robinsonae (Archosauromorpha: Allokotosauria) from the Upper Triassic lower Maleri Formation, Pranhita-Godavari Basin, India. The Anatomical Record. DOI: 10.1002/ar.25392

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[Paleontology • 2024] Austronaga minuta • A small-sized dinocephalosaurid archosauromorph (Diapsida: Dinocephalosauridae) from the Middle Triassic of Yunnan, southwestern China

 Austronaga minuta

Wang, Lei & Li, 2024

  Researchgate.net/publication/377413090

Abstract

Among numerous marine reptiles discovered in the Triassic eastern Tethys, today’s Southern China, Dinocephalosaurus is a bizarre animal comparable to European Tanystropheus in developing a prominently long neck. These two taxa are respectively assigned to Dinocephalosauridae and Tanystropheidae, and the two families and other basal members collectively form an early-diverging clade of Archosauromorpha. Here we report a new archosauromorph specimen, IVPP V18579, excavated from the lower Middle Triassic (Anisian), from Luoping, Yunnan in southwestern China. Compared with all the hitherto known dinocephalosaurids and tanystropheids, this skeletally mature individual is exclusively similar to Dinocephalosaurus in a number of characteristics, particularly with the long posterodorsal process of the premaxilla extending posteriorly beyond the level of the external nares, the concave posterior margin of the anteroposteriorly broad quadrate, and the strongly expanded distal end of the chevron in most of the caudal vertebrae. However, this reptile is much smaller than Dinocephalosaurus and different from Dinocephalosaurus and the other dinocephalosaurid, Pectodens, in many aspects, such as an anteriorly tapering long rostrum, the dentition composed of short conical teeth with less heterodonty, relatively but obviously tall neural spines of the axis and the anterior cervical vertebrae. Our phylogenetic analysis suggests that the new archosauromorph is a dinocephalosaurid, and then we erect Austronaga minuta gen. et sp. nov. based on this specimen. Detailed comparisons in osteological anatomy and the discussion about its potential aquatic adaptation of this new taxon are also provided.

Key words: Luoping, Yunnan, East Tethys, Triassic, marine reptile, Archosauromorpha, Dinocephalosauridae, osteological anatomy

Diapsida Osborn, 1903

Archosauromorpha Huene, 1946 sensu Dilkes, 1998

Dinocephalosauridae Spiekman et al., 2021

Austronaga minuta gen. et sp. nov.

Etymology: Austronaga, from the Latin “auster” or “austral” meaning south or southern referring to the South China Block where this taxon occurred, combining with “naga”, an Asian mythological figure that is snake-like and associated with water; minuta meaning small refers to the relatively small body size of this animal compared with most of its Triassic marine archosauromorph relatives. 

Wei Wang, Hong Lei and Chun Li. 2024. A small-sized dinocephalosaurid archosauromorph from the Middle Triassic of Yunnan, southwestern China. Vertebrata Palasiatica.  DOI: 10.19615/j.cnki.2096-9899.231013

https://www.vertpala.ac.cn/CN/10.19615/j.cnki.2096-9899.231013

Researchgate.net/publication/377413090_A_small-sized_dinocephalosaurid_archosauromorph_from_the_Middle_Triassic_of_Yunnan_China

 

摘要：现在的中国南方地区在三叠纪时期曾位于特提斯洋东部。在该区域产出的众多海生爬行动物中，恐头龙(Dinocephalosaurus)的形态特化，颈部极度增长，可与时代略晚的长颈龙(Tanystropheus)相比拟。这两种爬行动物分别归属于恐头龙科(Dinocephalosauridae)和长颈龙科(Tanystropheidae), 而这两个科的成员加之另外一些基干物种代表了主龙型类(Archosauromorpha)中一系列早期分异出的支系。报道一件产自云南罗平地区中三叠世安尼期地层的主龙型类成年个体新标本IVPP V18579, 与目前已知的早期主龙型类成员相比，该标本显示出与恐头龙属一致但区别于其他属种的特征，主要包括前颌骨发育有超过外鼻孔后缘的较长后背侧突，方骨前后向较宽大且具有后边缘的凹缺，大部分尾椎上的人字骨带有远端前后向的延展。然而，新标本体型明显小于恐头龙，且显示出与恐头龙属和梳齿龙属(另一恐头龙科成员)不同的鉴别特征，例如吻部窄长、牙齿短锥状且异齿性弱、枢椎和前部颈椎的神经棘显著更高等。基于最新的用于早期主龙型类系统发育分析的特征矩阵，系统发育分析结果确定V18579代表一个新的恐头龙科成员，在恐头龙科中与恐头龙属互为姊妹群关系。于是基于V18579建立了一新属新种：玲珑南蛇龙(Austronaga minuta), 同时对其进行了详细的解剖学特征描述，并讨论了它可能具有的水生适应性。

关键词: 云南罗平, 东特提斯, 三叠纪, 海生爬行动物, 主龙型类, 恐头龙科, 骨骼学解剖

[Paleontology • 2023] Bentonyx sidensis • Unique Dentition of rhynchosaurs (Archosauromorpha: Rhynchosauria) and their Two-phase Success as Herbivores in the Triassic

Bentonyx sidensis  Langer, Montefeltro, Hone, Whatley & Schultz, 2010

in Sethapanichsakul, Coram & Benton, 2023. 

DOI: 10.1111/pala.12654

Abstract

Rhynchosaurs were key herbivores over much of the world in the Middle and Late Triassic, often dominating their faunas ecologically, and much of their success may relate to their dentition. They show the unique ankylothecodont mode of tooth implantation, with deep roots embedded in the bone of the jaw and low crowns that were rapidly worn down in use. During growth, the main area of oral food processing, located in the middle and posterior portions of the occlusal surfaces of the jaws, moved posteriorly relative to the anterior tips of the jaws, which curved up. As the maxilla and dentary grew by addition of new bone posteriorly, the dental lamina fed in new teeth at the back of the tooth rows. CT scanning of the holotype skull of Bentonyx sidensis from the Middle Triassic of England reveals previously concealed details of the dentition. Together with new dentary material from the same location, this has enabled us to examine the tooth replacement process and elucidate ontogenetic changes in dentition and jaw morphology as the animals aged. There were major changes in rhynchosaur anatomy and function through their evolutionary history, with the early forms of the Middle Triassic dying out before or during the Carnian Pluvial Episode (233–232 Ma), and the subclade Hyperodapedontinae, with broad skulls and adaptations to chop tough vegetation, subsequently diversifying worldwide in a successful ecological expansion until their global extinction 227–225 Ma.

Keywords: dentition, rhynchosaur, tooth replacement, herbivory, Triassic, Carnian Pluvial Episode

Bentonyx sidensis 

 

Thitiwoot Sethapanichsakul, Robert A. Coram and Michael J. Benton. 2023. Unique Dentition of rhynchosaurs and their Two-phase Success as Herbivores in the Triassic. Palaeontology. 66(3); e12654. DOI: 10.1111/pala.12654

[Paleontology • 2023] Gracilicollum latens • A New Long-necked archosauromorph from the Guanling Formation (Anisian, Middle Triassic) of southwestern China and its implications for Neck Evolution in tanystropheids

 

Gracilicollum latens 

Wang, Spiekman, Zhao, Rieppel, Scheyer, Fraser & Li, 2023. 

DOI: 10.1002/ar.25216 

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Abstract

A long neck is an evolutionary innovation convergently appearing in multiple tetrapod lineages, including groups of plesiosaurs, non-archosauriform archosauromorphs, turtles, sauropodomorphs, birds, and mammals. Among all tetrapods both extant and extinct, two Triassic archosauromorphs, Tanystropheus and Dinocephalosaurus, have necks that are particularly elongated relative to the lengths of their trunks. However, the evolutionary history of such hyper-elongated necks in these two archosauromorph clades remains unknown, partially because known close relatives such as Macrocnemus and Pectodens possess only moderately elongated necks. Here, we describe a newly discovered early diverging archosauromorph, Gracilicollum latens gen. et sp. nov., based on a specimen comprising a partial neck and an incompletely preserved skull. The long neck is composed of at least 18 cervical vertebrae. The dentition suggests that this new taxon most likely represents an aquatic piscivore, similar to Dinocephalosaurus and Tanystropheus hydroides. Despite possessing a high number of cervical vertebrae, Gracilicollum gen. nov. is recovered as a tanystropheid in an evolutionary grade between Macrocnemus and Tanystropheus rather than as a close relative of Dinocephalosaurus, a result that is primarily attributable to the presence of palatal teeth and the anatomy of the cervical vertebrae in Gracilicollum gen. nov. Considering the information provided by the new specimen, we provide a detailed discussion of the cervical evolution in dinocephalosaurids and tanystropheids, which is shown to be highly complex and mosaic in nature.

Keywords: Archosauromorpha, Dinocephalosauridae, fossil, marine reptile, neck evolution, South China, Tanystropheidae, Triassic, vertebral column

 Gracilicollum latens gen. et sp. nov.

Wei Wang, Stephan N. F. Spiekman, Lijun Zhao, Olivier Rieppel, Torsten M. Scheyer, Nicholas C. Fraser and Chun Li. 2023. A New Long-necked archosauromorph from the Guanling Formation (Anisian, Middle Triassic) of southwestern China and its implications for Neck Evolution in tanystropheids. The Anatomical Record. DOI: 10.1002/ar.25216

 twitter.com/AnatRecord/status/1645796594619383808

[Paleontology • 2023] Beesiiwo cooowuse • A New Rhynchosaur Taxon (Archosauromorpha: Rhynchosauridae: Hyperodapedontinae) from the Popo Agie Formation, Wyoming: Implications for A Northern Pangean Early-Late Triassic (Carnian) Fauna

 

Beesiiwo cooowuse

Fitch, Haas,C’Hair, Ridgley, Ridgley, Oldman, Reynolds & Lovelace, 2023

DOI: 10.3390/d15040544

artwork: Gabriel Ugueto  twitter.com/SerpenIllus

  Abstract

New discoveries in the lower Popo Agie Formation (lower carbonate unit) of central Wyoming necessitated a reevaluation of USNM 494329 from the same unit, the only known hyperodapedontine rhynchosaur in western North America. Well known from Gondwanan deposits, hyperodapedontines appear to be restricted to the Carnian age (Late Triassic), with the exception of Teyumbaita in the earliest Norian age (Late Triassic) of Brazil. Initially assigned to c.f. ‘Hyperodapedon’ sanjuanensis, our phylogenetic analyses reject this hypothesis, in support of a sister relationship between USNM 494329 (Beesiiwo cooowuse, gen. et sp. nov.) and Oryctorhynchus bairdi forming an early-diverging clade that is only distantly related to ‘H.’ sanjuanensis. Five additional specimens recovered from the lower Popo Agie are described. Three are referred to B. cooowuse, and another two are placed closer to Hyperodapedon and the remainder of Hyperodapedontinae. Our analysis demonstrates potential temporal distinction between a grade of earliest-diverging hyperodapedontines (including all Wyoming taxa) and a exclusively Late Carnian, Southern Pangaean hyperodapedontine clade (including ‘H.’ sanjuanensis). We consider the lower Popo Agie Formation to represent the first nonmarine Late Triassic unit of Western North America that can be confidently restricted to the Carnian age.

Keywords: Popo Agie Formation; Late Triassic; rhynchosaur; Hyperodapedontinae; Carnian

(A) The type specimen for Beesiiwo cooowuse (USNM 494329); occlusal view (top left/center) and axial cross section (bottom left/center) of posterior maxilla, and occlusal view of dentary (top/bottom right). Note that the row of teeth medial to L1 and L2 is not M1, but a fragment of the dentary that remains slotted into the longitudinal groove of the maxilla.
(B–D) Occlusal view of three left maxillae from Cottonwood Creek referred to Beesiiwo cooowuse. Note the presence of M1 and absence of any additional medial rows.

All scale bars = 1 cm. Illustration CC by Jim Morrison.

 Systematic Paleontology

Sauria McCartney, 1802, sensu Gauthier et al., 1988

Archosauromorpha von Huene, 1946 sensu Dilkes, 1998 

Rhynchosauridae Cope, 1871 sensu Dilkes, 1998 

Hyperodapedontinae (Chatterjee, 1969 nom. trans. ex Lydekker, 1885 sensu Langer and Schultz, 2000)

Beesiiwo gen. nov.

Etymology: Beesiiwo, from Arapaho “Beesiiwó” (pronounced “ Bah - se - wa - ’ ”, with the apostrophe representing a glottal stop) meaning “big lizard”.

Pronunciation guide: The sound for b is roughly as in English, but more like b before other consonants or at the end of a word; the sound for ee is as in the English ‘bat’ but is held longer; the sound for s is like in English, but always a nonvocailized, never vocalized as in some English s and all English z sounds; the sound for ii is as in English ‘beat’ but held longer; the sound for o is as in English ‘hot; the sound for ‘ is a glottal stop, as in the middle of oh-oh! in English.

 

Beesiiwo cooowuse sp. nov.

Holotype: USNM 494329, fragment of a left maxilla and a left dentary.

 

Etymology: cooowuse, from Arapaho “ co’ oowu se’ ” (pronounced “ ja’ aw-wu sa’ ”, with the apostrophe representing a glottal stop); meaning the “Alcova area”, central WY.

Pronunciation guide: The sound for c is like that of the English j but without any puff of air and more like the English ch before other consonants or at the end of a word; the sound for oo is as in the English ‘got’ but held longer; the sound for w is like in English; the sound for u is as in the English ‘put’; the sound for e is as in English ‘bet’.

Occurrence: The type specimen was collected as clasts within a 0.5–1 m thick microconglomerate in the lower carbonate unit of the Popo Agie Formation near Hole in the Wall, Southern Bighorn Mountains, WY (‘Willow Creek’ of [22]). Referred material (see below) was collected as rounded to partially rounded clasts in a 0.5–2 m thick microconglomerate also referred to the lower carbonate unit of the Popo Agie Formation, Cottonwood Creek near Alcova, WY.

Diagnosis: Diagnosed by the following combination of character-states: maxilla with two lateral tooth rows and one medial tooth row; teeth of the lateral tooth row L1 lacking prominent anterolingual flanges; crest-shaped areas, respectively, medial and lateral to a longitudinal groove on the occlusal surface of the maxilla; dentary without a row of lingual teeth.

 Life reconstruction of Beesiiwo cooowuse with Heptasuchus clarki in the background representing the known fauna from the lower carbonate unit of the Popo Agie Formation.

artwork: Gabriel Ugueto  twitter.com/SerpenIllus

 

Adam J. Fitch, Merle Haas,Wayne C’Hair, Eugene Ridgley, Ben Ridgley, Devin Oldman, Crystal Reynolds and David M. Lovelace. 2023. A New Rhynchosaur Taxon from the Popo Agie Formation, WY: Implications for a Northern Pangean Early-Late Triassic (Carnian) Fauna. Diversity. 15(4), 544. DOI: 10.3390/d15040544

  twitter.com/SerpenIllus/status/1645430371939414017

[Paleontology • 2021] Niche Partitioning shaped Herbivore Macroevolution through the early Mesozoic

in Singh, Elsler, Stubbs, ... et Benton, 2021. 

DOI: 10.1038/s41467-021-23169-x  

twitter.com/PalaeoSingh 

Abstract

The Triassic (252–201 Ma) marks a major punctuation in Earth history, when ecosystems rebuilt themselves following the devastating Permian-Triassic mass extinction. Herbivory evolved independently several times as ecosystems comprising diverse assemblages of therapsids, parareptiles and archosauromorphs rose and fell, leading to a world dominated by dinosaurs. It was assumed that dinosaurs prevailed either through long-term competitive replacement of the incumbent clades or rapidly and opportunistically following one or more extinction events. Here we use functional morphology and ecology to explore herbivore morphospace through the Triassic and Early Jurassic. We identify five main herbivore guilds (ingestion generalists, prehension specialists, durophagous specialists, shearing pulpers, and heavy oral processors), and find that herbivore clades generally avoided competition by almost exclusively occupying different guilds. Major ecosystem remodelling was triggered multiple times by external environmental challenges, and previously dominant herbivores were marginalised by newly emerging forms. Dinosaur dominance was a mix of opportunity following disaster, combined with competitive advantage in their new world.

 

Suresh A. Singh, Armin Elsler, Thomas L. Stubbs, Russell Bond, Emily J. Rayfield and Michael J. Benton. 2021. Niche Partitioning shaped Herbivore Macroevolution through the early Mesozoic. Nature Communications. 12: 2796. DOI: 10.1038/s41467-021-23169-x

  twitter.com/PalaeoSingh/status/1393205019034456064

  twitter.com/DrTLStubbs/status/1393203880272465926

[Paleontology • 2021] Bharitalasuchus tapani • A New Erythrosuchid Archosauriform (Archosauriformes: Erythrosuchidae) the Middle Triassic Yerrapalli Formation of south-central India

[upper] Erythrosuchus africanus Broom, 1905
[lower] Bharitalasuchus tapani 

Ezcurra, Bandyopadhyay & Gower, 2021 

  ameghiniana.org.ar 

MACNCONICET.gob.ar

Abstract

Erythrosuchid archosauriforms are quadrupedal carnivorous reptiles with a proportionally huge skull. They represent one of the first evolutionary radiations of medium to large predatory diapsids after the Permo–Triassic mass extinction. Erythrosuchids are known from Lower–Middle Triassic rocks of South Africa, Russia, and China, and there have been preliminary reports from the Middle Triassic Yerrapalli Formation of south-central India. Here we describe, compare and figure for the first time these Indian erythrosuchid remains. We erect the new genus and species Bharitalasuchus tapani based on a holotype and paratype that preserve tooth-bearing cranial fragments, at least 17 presacral vertebrae, some ribs and probable intercentra, and partial shoulder and pelvic girdles and hindlimb and allow recognizing a series of autapomorphies and unique combination of character states among erythrosuchids. Our phylogenetic analysis recovered Bharitalasuchus tapani most closely related to Shansisuchus shansisuchus and Chalishevia cothurnata from the late Anisian of China and Ladinian of Russia, respectively. The phylogenetic affinities of this new taxon and a revision of the tetrapod assemblage of the Yerrapalli Formation shed light on the age of this unit. The presence of the Wadiasaurus-Rechnisaurus-Bharitalasuchus association in the Yerrapalli Formation closely resembles the Sinokannemeyeria-Shansisuchus dicynodont-erythrosuchid association of late Anisian to early Ladinian Chinese units. This evidence supports a post-early–middle Anisian age, even possibly early Ladinian, for the Yerrapalli Formation. The presence of possibly one of the last erythrosuchids in India would indicate that the clade still retained both a northern and southern Pangean distribution before its extinction.

Keywords: Archosauriformes, Erythrosuchidae, Phylogeny, Biostratigraphy, Pranhita-Godavari Basin

Martin D. Ezcurra, Saswati Bandyopadhyay and David J. Gower. 2021. A New Erythrosuchid Archosauriform the Middle Triassic Yerrapalli Formation of south-central India. Ameghiniana. 58(2), 132–168. DOI: 10.5710/AMGH.18.01.2021.3416

  ameghiniana.org.ar/index.php/ameghiniana/article/view/3416

  twitter.com/MacnVp/status/1388136263279054850

Paleontólogos liderados por un investigador del CONICET dan a conocer una nueva especie de reptil de la India de 240 millones de años de antigüedad, similar una criatura de Star Wars

MACNCONICET.gob.ar/paleontologos-liderados-por-un-investigador-del-conicet-dan-a-conocer-una-nueva-especie-de-reptil-de-la-india-de-240-millones-de-anos-de-antiguedad-similar-una-criatura-de-star-wars

[Paleontology • 2020] Oryctorhynchus bairdi • A New Rhynchosaur (Reptilia, Archosauromorpha) from the Upper Triassic of Eastern North America

 Oryctorhynchus bairdi

Sues, Fitch & Whatley, 2020

DOI: 10.1080/02724634.2020.1771568 

 facebook.com: Adam Fitch

ABSTRACT

This paper provides a description and analysis of cranial remains of a rhynchosaur from the Upper Triassic Evangeline Member of the Wolfville Formation of Nova Scotia, Canada. This material, primarily comprising jaw elements, represents the first definitive record of Late Triassic rhynchosaurs from eastern North America. All cranial bones can be assigned to Hyperodapedontinae. The dentition of the Nova Scotian hyperodapedontine differs from those of Hyperodapedon and Isalorhynchus. The maxilla apparently did not have more than two lateral rows and two medial rows of teeth. The teeth of the lateral row closest to the single groove dividing the maxillary tooth plate are more than twice as large as those of the medial row closest to the groove. The lateral and medial tooth-bearing portions of the maxilla become increasingly crest-like during ontogeny. The dentary lacks a lingual row of teeth. Based on this combination of features, the hyperodapedontine material from the Evangeline Member is assigned to a new taxon, Oryctorhynchus bairdi, gen. et sp. nov., which is the sister species to an unnamed hyperodapedontine taxon from Wyoming. This clade was recovered as the sister taxon to Hyperodapedon spp. in the phylogenetic analysis. The late Carnian or earliest Norian tetrapod assemblage from the Evangeline Member represents a mixture of faunal elements from a wide paleolatitudinal range, suggesting a more cosmopolitan distribution for continental tetrapods during the early Late Triassic than previously assumed.

SYSTEMATIC PALEONTOLOGY 

REPTILIA Laurenti, 1768 

DIAPSIDA Osborn, 1903, sensu Benton, 1985 

ARCHOSAUROMORPHA Huene, 1946, sensu Benton, 1985 

RHYNCHOSAURIDAE Cope, 1871, sensu Dilkes, 1998

HYPERODAPEDONTINAE Lydekker, 1885, sensu Schultz, Langer, and Montefeltro, 2016 

ORYCTORHYNCHUS BAIRDI, gen. et sp. nov.

Etymology— From Greek oryktos, dug, mined, alluding to the inferred digging habits of rhynchosaurs and the derivation of the name ‘Minas Basin’ from the French ‘les mines,’ and Greek rhynchos, snout. The specific epithet honors the late Donald Baird for his pioneering work on Triassic tetrapods from Nova Scotia.

Hans-Dieter Sues, Adam J. Fitch and Robin L. Whatley. 2020. A New Rhynchosaur (Reptilia, Archosauromorpha) from the Upper Triassic of Eastern North America. Journal of Vertebrate Paleontology. e1771568. DOI: 10.1080/02724634.2020.1771568

  facebook.com/permalink.php?story_fbid=2691616384412717&id=100006931449123