[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 • 2024] Cranial Osteology and Paleoneurology of Tarjadia ruthae: An erpetosuchid pseudosuchian from the Triassic Chañares Formation (late Ladinian-?early Carnian) of Argentina

 

Tarjadia ruthae Arcucci & Marsicano, 1998
 

in Desojo, von Baczko, Ezcurra, Fiorelli, Martinelli, ... et Lacerda, 2026. 

DOI: doi.org/10.1002/ar.25382 

Reconstruction: Jorge Blanco

 x.com/AnatRecord

 

Abstract

Tarjadia ruthae is a quadrupedal terrestrial pseudosuchian from the Middle-early Upper Triassic of the Chañares Formation, La Rioja Province, Argentina. Originally, this species was identified as an indeterminate archosaur and later as a doswelliid archosauriform based on very fragmentary specimens characterized by the ornamentation of the skull roof and osteoderms. Additional specimens (including skulls and postcrania) recovered in the last decade show that Tarjadia is an erpetosuchid, an enigmatic pseudosuchian group composed of six species registered in Middle-Upper Triassic continental units of Tanzania, Germany, Scotland, North America, Brazil, and Argentina. Tarjadia ruthae from Argentina and Parringtonia gracilis from Tanzania are the best preserved and more abundant species. Although the monophyly of Erpetosuchidae is well supported, alternative high-level positions within Archosauria have been suggested, such as sister taxon to Crocodylomorpha, Aetosauria, or Ornithosuchidae. In order to improve the knowledge about the erpetosuchids, we performed a detailed description and paleoneurological reconstruction of the skull of Tarjadia ruthae, based on two articulated partial skulls (CRILAR-Pv 478 and CRILAR-Pv 495) and other fragmentary specimens. We analyzed the stratigraphic and geographic occurrence of historical and new specimens of Tarjadia and provided a new emended diagnosis (the same for the genus as for the species, due to monotypy) along with a comparative description of the cranial endocast. The skull of Tarjadia is robust, with a thick and strongly ornamented skull roof, triangular in dorsal view, with concave lateral margins at mid-length that form an abrupt widened posterior region. The external nares are the smallest openings of the skull. The antorbital fossa is deeply excavated and has a small heart-shaped fenestra with both lobes pointing anteriorly. The supratemporal fenestrae are as large and rounded as the orbits, and the infratemporal fenestrae are L-shaped with an extensive excavation along the jugal, quadratojugal and quadrate. The hemimandibles are low, slightly concave on the dentigerous region and strongly convex on the posterior region, conferring them a S-shaped profile in dorsal view. The external mandibular fenestra is small and elliptic, being twice longer than high. The maxillary dentition is restricted to the anterior to mid region of the rostrum. Since the braincase of both specimens is partially damaged, the dorsal surface of the brain could not be entirely reconstructed. As a result, the endocast is anteroposteriorly elongated and seemingly flat, and the cephalic flexure seems to be lower than expected for a suchian. The labyrinth is twice wider than high, the semicircular canals are remarkably straight, and the anterior canal is longer than the posterior one.

Keywords: anatomy, Archosauria, Erpetosuchidae, neuroanatomy, skull

Systematic paleontology

Archosauriformes Gauthier et al., 1988.

Archosauria Cope, 1869 sensu Gauthier & Padian, 1985.

Pseudosuchia von Zittel, 1887–1890 sensu Gauthier & Padian, 1985.

Erpetosuchidae Watson, 1917 sensu Nesbitt & Butler, 2013.

Tarjadia ruthae Arcucci & Marsicano, 1998

Life reconstruction of Tarjadia ruthae by Jorge Blanco.

J. B. Desojo, M. B. von Baczko, M. D. Ezcurra, L. E. Fiorelli, A. G. Martinelli, P. Bona, M. J. Trotteyn and M. Lacerda. 2024. Cranial Osteology and Paleoneurology of Tarjadia ruthae: An erpetosuchid pseudosuchian from the Triassic Chañares Formation (late Ladinian-?early Carnian) of Argentina. The Anatomical Record. DOI: doi.org/10.1002/ar.25382 [23 January 2024]

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[Paleontology • 2026] New Fossil unveils the Dentary Anatomy of the rare lepidosauromorph Cargninia enigmatica from the Upper Triassic of Southern Brazil

 Cargninia enigmatica Bonaparte, Schultz, Soares & Martinelli, 2010, 

in Damke, Dalle-Laste,  Kerber, Roberto-da-Silva et Müller, 2026. 

DOI: doi.org/10.1002/ar.70268

Artwork by Márcio L. Castro.

Abstract

Nowadays, Lepidosauria is a diverse group represented by squamates and the rhynchocephalian tuatara. However, their origins date back to the end of the Permian Period, when the stem lineages Lepidosauromorpha and Archosauromorpha diverged. Within the lepidosauromorph stem lineage, a few species have been described with unstable phylogenetic placements. In Brazilian strata, the only representative of this lineage is the rare species Cargninia enigmatica. The taxon was found in Norian beds (upper portion of the Candelária Sequence) and is known from the posterior end of a dentary and a tentatively referred partial maxilla. Here, we describe a new specimen (CAPPA/UFSM 0519) referred to Cargninia enigmatica, consisting of a partial dentary recovered from the type locality. The specimen provides new anatomical information on the anterior portion of the dentary. In addition, for the first time, the phylogenetic placement of Cargninia enigmatica was investigated in a computational framework, and the results are congruent with previous suggestions that it represents a non-lepidosaur lepidosauromorph. Finally, the new specimen reveals details of the anatomy of the mandibular ramus of the trigeminal nerve, demonstrating that it shares a similar condition with its extant relatives.

Keywords: Caturrita Formation, Gondwana, Lepidosauromorpha, Norian, Pangea

Left dentary of CAPPA/UFSM 0519 in lateral view. (a) Photograph. (b) Interpretative drawing. (c) Detail of the rostralmost preserved teeth. (d) Additional details of the second and third preserved teeth. fo, foramina.

SYSTEMATIC PALEONTOLOGY

DIAPSIDA Osborn, 1903

SAURIA Macartney, 1802

LEPIDOSAUROMORPHA Gauthier, 1984 (sensu Gauthier et al., 1988)

Cargninia enigmatica Bonaparte et al., 2010

 Holotype: UFRGS-PV-1027-T, posterior end of a left dentary with five preserved teeth.

 Type locality, age, and horizon: Linha São Luiz site (29°33′45″S, 53°26′48″W), municipality of Faxinal do Soturno, Rio Grande do Sul, Brazil. Candelária Sequence of the Santa Maria Supersequence (Horn et al., 2014; Zerfass et al., 2003). These layers are early Norian in age (225.42 ± 0.37) (Langer et al., 2018).

New referred material: CAPPA/UFSM 0519, partial left dentary with several teeth. The specimen was collected from the type locality.

  Amended diagnosis: In addition to the unique traits of Cargninia enigmatica listed by Bonaparte et al. (2010) and Romo de Vivar et al. (2020), we recognize the following additional features based on the study of CAPPA/UFSM 0519 that distinguish the species from closely related taxa: the symphyseal region is medially recurved and formed by the Meckelian groove, and the presence of foramina restricted to the anterior region of the dentary.

A landscape from the Late Triassic of southern Brazil showing Cargninia enigmatica being observed by the sauropodomorph dinosaur Macrocollum itaquii. Artwork by Márcio L. Castro.

Lísie Vitória Soares Damke, Vitória Zanchett Dalle-Laste, Leonardo Kerber, Lúcio Roberto-da-Silva and Rodrigo Temp Müller. 2026. New Fossil unveils the Dentary Anatomy of the rare lepidosauromorph Cargninia enigmatica from the Upper Triassic of Southern Brazil. The Anatomical Record. DOI: doi.org/10.1002/ar.70268  [04 July 2026]

[Paleontology • 2026] Silescelida acristata • A New eucrocopodan Archosauriform from the Middle Triassic of southern Brazil and the Phylogeny of Euparkeriidae

Silescelida acristata 

Garcia, Cerqueira, Battista,  Andrade & Müller, 2026

DOI: doi.org/10.1038/s41598-026-53740-9 

life reconstruction by Matheus Fernandes Gadelha. 

Abstract

Archosauriformes comprise a diverse range of reptiles, including the crown-group Archosauria, which flourished during the Triassic Period. Early-diverging archosauriforms, such as proterosuchids and erythrosuchids, are becoming progressively well-known due to recent studies and consistently resolve at the base of the clade. More crownward, Eucrocopoda includes archosauriform taxa that increasingly approximate the ancestral archosaur body plan. Early-diverging eucrocopodan archosauriforms have a widespread paleogeographic record but remain poorly understood in terms of ingroup relationships. Within this radiation, Euparkeriidae is particularly challenging, because its ingroup composition and monophyly is debated, with some authors supporting a non-monospecific Euparkeriidae, whereas others fail to recover this hypothesis. The eponymous Euparkeria capensis is known from the Early to Middle Triassic of South Africa, whereas other putative euparkeriids are primarily known from the Early to Middle Triassic of China, Germany, Poland, and Russia. Here, we describe a new early-diverging eucrocopodan (Silescelida acristata gen. et sp. nov.) from the Middle Triassic of southern Brazil. Phylogenetic analyses incorporating this taxon suggest a possible placement within Euparkeriidae, though its position shows instability depending on the operational taxonomic units considered, especially among other putative euparkeriids. This discovery not only informs on the temporal and paleogeographic distribution of euparkeriids but also sheds light on the origin and early evolution of eucrocopodans, representing the first record of this archosauriform grade in the Triassic of Brazil. More broadly, the new taxon underscores the significance of South American Triassic deposits within the evolutionary history of archosauriforms.

Archosauromorpha von Huene, 1946 sensu Gauthier, 2020

Archosauriformes Gauthier et al., 1988 sensu Gauthier, 2020 

Eucrocopoda Ezcurra, 2016

cf. Euparkeriidae von Huene, 1920 sensu Sookias and Butler, 2013

Provenance and material of Silescelida acristata gen. et sp. nov.
 (A) Map of the Posto site and the surface distribution of the geologic units in the area. (B) General view of the Posto site. (C) Studied specimen MCP 4186-PV (holotype of Silescelida acristata gen. et sp. nov.) showing association between its elements prior to mechanical preparation.
(D) Silhouette and preserved skeletal elements (not to scale) of Silescelida acristata gen. et sp. nov. (ilium reversed).

Abbreviations: fe, femur; il, ilium; sc, scapula. Silhouette and life reconstruction of Silescelida acristata gen. et sp. nov. by Matheus Fernandes Gadelha. Map was generated with GIMP 3.0 (gimp.org) based on the geological map of Rio Grande do Sul (https://rigeo.sgb.gov.br/bitstream/doc/10301/2/Geologico_MDT.pdf).

Silescelida acristata gen. et sp. nov.  

Holotype. MCP 4186-PV, a left scapula, a right ilium, and a left femur (Fig. 1C, D). The elements were found in association (attached to each other) and are size-compatible; therefore, they are considered to belong to the same individual.

Type locality, age, and horizon. Posto (or Posto de Gasolina; Fogliarini) site (29°37’38.9”S 53°22’06.5”W), municipality of Dona Francisca, Rio Grande do Sul, Brazil (Fig. 1A, B). Dinodontosaurus AZ of the Pinheiros-Chiniquá Sequence of the Santa Maria Supersequence, Paraná Basin51,52. It is considered Ladinian in age30,35,53,54,55,56,57,58.

Diagnosis. The holotype of Silescelida acristata differs from all other known non-archosaurian archosauriforms in the following combination of traits: scapular blade without an anteroposterior constriction at its base; asymmetrical expansion of the scapular blade at its dorsal portion; straight posterior margin of the scapular blade, forming a right angle with the dorsal margin of the glenoid; elliptical tuber for the m. triceps dorsal to the glenoid; dorsal margin of the dorsal iliac blade straight in dorsal and lateral views; dorsal iliac blade as deep as the acetabulum; notch between the ischiadic peduncle and the ventral apex of the medial acetabular wall; medially expanded femoral head; absence of a longitudinal groove on the proximal surface of the femoral head; posteromedial tuber as the only well-developed tuber on the femoral head; absence of an elevated mound or crest-like structure as the attachment site for the m. caudofemoralis (local autapomorphy); extensor fossa on the anterior surface of the femoral distal end; distal femoral condyles with the same degree of ventral development (not uneven).

Etymology. The generic name combines the Latin siles (“silence”) and the Greek skelēs (“hind leg”), referencing the loss of the proximal femur bearing the specimen’s collection code, which obscured its provenance until its recent rediscovery. The specific epithet derives from the Latin prefix a- (“without”) and cristāta (“crested”), referring to the absence of a crest or flange attachment site for the m. caudofemoralis (= fourth trochanter), a diagnostic feature of the taxon.

Silescelida acristata gen. et sp. nov. life reconstruction.

 Artwork by Matheus Fernandes Gadelha. 

Biogeography of early-diverging eucrocopodans and paleoart depicting Silescelida acristata gen. et sp. nov. in life.
 (A) Triassic world map depicting the paleogeographic distribution of early-diverging eucrocopods. Classification is based on the phylogenetic analyses in this contribution. Silhouettes (not to scale) based on the skeletal reconstruction of Euparkeria capensis by Demuth et al.83. Dorosuchus neoetus is based on the type-series and Osmolskina czatkowicensis is based on the holotype.
(B) Silescelida acristata gen. et sp. nov. life reconstruction. Artwork by Matheus Fernandes Gadelha. Map was generated with GIMP 3.0 (gimp.org) based on The Paleobiology Database (paleobiodb.org).

 

Maurício S. Garcia, Gabriela M. Cerqueira, Francesco Battista, Marco B. de Andrade and Rodrigo T. Müller. 2026. A New eucrocopodan Archosauriform from the Middle Triassic of southern Brazil and the Phylogeny of Euparkeriidae. Scientific Reports. 16: 16585. DOI: doi.org/10.1038/s41598-026-53740-9  [10 June 2026]

 

[Paleontology • 2026] Carinthiasuchus kandutschi • A New Archosaur (Reptilia: Diapsida) from the Triassic of Austria

 

Carinthiasuchus kandutschi 

 Vecchia & Cau, 2026 

DOI: doi.org/10.54103/2039-4942/29890

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Abstract 

A partial skeleton of a small reptile with a distinctive maxilla, dentition, caudal vertebrae and osteoderms from the marine Partnach Formation (Ladinian-earliest Carnian) near Jadersdorf (Gitschtal, Hermagor) in the Gailtal Alps of Carinthia (Austria), represents a new archosaur taxon Carinthiasuchus kandutschi gen. n. sp. n.. It is diagnosed by autapomorphies in the anterior process and subnarial foramen of the maxilla, accessory articular processes in the neural arches of mid-distal caudal vertebrae, and shape and arrangement of the caudal osteoderms. It also shows a unique combination of features regarding the extent of the antorbital fossa in the maxilla and the morphology of its ventral edge, dentary shape, dentition, caudal vertebrae elongation and morphology. A segment of 16 mid-distal caudal vertebrae is one of the better articulated tail segments ever found in Triassic archosaurs, showing the arrangement of the dorsal osteoderms and the presence of accessory processes in the neural arches stiffening the posterior termination of the tail. Phylogenetic analysis recovered Carinthiasuchus kandutschi as a pseudosuchian in a basal position within the Poposauroidea. Absence of swimming adaptation in the tail and the presence of terrestrial plant remains in the same outcrop suggest terrestrial habits for this archosaur reptile.

Carinthiasuchus kandutschi, gen. n. sp. n., Nockalm7030u, holotype. Scale bar equals 100 mm.

Carinthiasuchus kandutschi, gen. n. sp. n., Nockalm7030u, ho-lotype, skull and mandible. (A) Photograph, (B) drawing (bone is gray and teeth darker gray).

Abbreviations: d, den-tary; f, frontal; j, jugal; la, lacrimal; mx, maxilla; n, nasal; pt, pterygoid; q, quadrate; snf, subnarial foramen; sq, squamo-sal; th, tooth; v, vomer; *, left element.

Legenda: 1 = actual margin of the bone; 2 = broken margin of the bone; 3 = margin of the impression of the bone; 4 = probable margin of the skeletal element; 5 = broken surface of the skeletal element. Scale bar is 10 mm.

Reptilia Laurenti, 1768 sensu Modesto & Anderson, 2004

Diapsida Osborn, 1903 

Archosauromorpha von Huene, 1946 sensu Dilkes, 1998

Archosauriformes Gauthier, Kluge & Rowe,1988

Archosauria Cope, 1869

Pseudosuchia Zittel, 1887-1890

Suchia Krebs, 1974 (sensu Nesbitt, 2011)

Paracrocodylomorpha Parrish, 1993

Poposauroidea Nopcsa, 1923

Carinthiasuchus kandutschi gen. n. sp. n.

Holotype: Nockalm7030u, part of the skull including the right maxilla with two teeth, part of the two mandibular rami, and parts of the mid-distal portion of the tail with osteoderms (Fig. 3).

Locality and stratigraphic horizon: Southern flank of Mt. Großboden NE of Jadersdorf in the Gitschtal close to Hermagor, Carinthia, SE Austria. Partnach-Schichten/Fellbach Kalk, Ladinian-lo-wermost Carnian.

Diagnosis. Carinthiasuchus kandutschi gen. n. sp. n. is an archosaur (see discussion) with the following apomorphies: short, straight and pointed anterior process of the maxilla with a dorsal articular facet and bordering dorsally a comparatively large subnarial foramen; accessory articular processes of the neural arches in the last middle and in the distal caudal vertebrae; paired and symmetrical paramedian osteoderms above the proximal mid-caudal vertebrae, drop-shaped, with coarse denticles along the margins posteriorly, with longitudinal median ridge dorsally but without sculpturing; single median row of elongated and lying 8-shaped osteoderms in the following mid-distal caudals with three osteoderms per vertebra, one above the middle of the vertebra and half on the anterior and ...

Etymology: The genus is named after Carinthia, the Latin name of Kärnten, the southernmost federate state of Austria where the specimen was discovered and the Greek term soúkhos (σούχος) for crocodile. The species name is inhonourof the discoverer of the holotype, Georg Kandutsch (Arriach/Hinterwinkl, Austria).

FABIO MARCO DALLA VECCHIA and ANDREA CAU. 2026. Carinthiasuchus kandutschi, A NEW ARCHOSAUR (REPTILIA: DIAPSIDA) from the Triassic of AUSTRIA. RIVISTA ITALIANA DI PALEONTOLOGIA E STRATIGRAFIA. 132(2); DOI: doi.org/10.54103/2039-4942/29890 [08-06-2026]

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[Paleontology • 2026] Labrujasuchus expectatus • A New shuvosaurid (Archosauria: Poposauroidea) from the Late Triassic (Norian) Hayden Quarry of New Mexico, U.S.A.

Labrujasuchus expectatus

Turner, Kernan, Laing, Pritchard, Stocker, Irmis, Smith, Werning & Nesbitt, 2026

DOI: doi.org/10.1080/02724634.2026.2618182

Artwork: Jorge Gonzalez/NHMLAC Dinosaur Institute

ABSTRACT

Bipedal shuvosaurid archosaurs were present for much of the Late Triassic Period. The clade is particularly diverse in Upper Triassic assemblages in the western U.S.A. Isolated bones are easily differentiated from contemporary archosaurs, but the two named North American species, Shuvosaurus inexpectatus and Effigia okeeffeae, display remarkably similar skeletons. Here we describe a new shuvosaurid species, Labrujasuchus expectatus, gen. et sp. nov., from the middle Norian (∼212 Ma) Hayden Quarry of northern New Mexico, U.S.A., located within the Petrified Forest Member of the Chinle Formation, that fills the temporal gap between the two species. The holotype consists of a partial skeleton, with additional shuvosaurid material from the Hayden Quarry likely pertaining to this taxon. This taxon is distinguished by four autapomorphies and assignable to Shuvosauridae based on a deep fossa present on the posterodorsal edge of the coracoid, the proximal portion of the humerus less than twice the width of the midshaft, the anteromedial tuber of the femur large and ‘hooked’ posteriorly, and a ventrally descended posterolateral portion of the femoral head. Recent Bayesian estimates of archosaur phylogeny and divergence times suggested a Middle Triassic split for Shuvosauridae as well as a decrease in the rate of morphological evolution for the clade relative to that of other archosaurs. The anatomical similarity of L. expectatus with other shuvosaurids is consistent with these estimated low rates, and the long gaps in the fossil record for the clade suggest that much of their evolutionary history remains to be sampled.

Reconstruction of Labrujasuchus expectatus, a new species of Shuvosauridae from Late Triassic rocks of Ghost Ranch, New Mexico.

Artwork: Jorge Gonzalez/NHMLAC Dinosaur Institute

SYSTEMATIC PALEONTOLOGY

ARCHOSAURIA Cope, 1870 (sensu Gauthier & Padian, 1985)

SUCHIA Krebs, 1974 (sensu Benton & Clark 1988)

SHUVOSAURIDAE Chatterjee, 1993 (sensu Nesbitt, 2011)

LABRUJASUCHUS gen. nov.

Type Species—Labrujasuchus expectatus

Etymology—The generic name Labrujasuchus (“la-broo-ha-soo-kus”) is derived from “Ranchos de los Brujos,” Ranch of the Witches, an old Spanish name for the Ghost Ranch area, and the Greek word Σοῦχος (suchus) meaning “crocodile.” It is masculine in gender.

 

LABRUJASUCHUS EXPECTATUS sp. nov.

Etymology—From the Latin “expectatus” for expected or awaited.

The species name is based on the anticipated nature of a shuvosaurid discovery at the Hayden Quarry.

Alan H. Turner, Ciara E. Kernan, Adam Laing, Adam C. Pritchard, Michelle R. Stocker, Randall B. Irmis, Nathan D. Smith, Sarah Werning and Sterling J. Nesbitt. 2026. A New shuvosaurid (Archosauria, Poposauroidea) from the Late Triassic (Norian) Hayden Quarry of New Mexico, U.S.A. Journal of Vertebrate Paleontology.  e2618182 DOI: doi.org/10.1080/02724634.2026.2618182  [26 May 2026]

[Paleontology • 2026] Eosphorosuchus lacrimosa • A Short-snouted ‘sphenosuchian’ with unusual Feeding Anatomy demonstrates that Ecological Specialization occurred early in Crocodylomorph Evolution

 

Eosphorosuchus lacrimosa

Margulis-Ohnuma, Ruebenstahl, Meyer & Bhullar, 2026

 

DOI: doi.org/10.1098/rspb.2026.0130 

Art by Julio Lacerda

Abstract

The early evolution and diversification of Crocodylomorpha is a key component of vertebrate evolution on land but is somewhat poorly understood as a result of limited data. We describe Eosphorosuchus lacrimosa gen. et sp. nov., an early crocodylomorph from the Late Triassic of Ghost Ranch, New Mexico, whose cranial anatomy is divergent from that of other early crocodylomorphs (including Hesperosuchus agilis, to which it had been tentatively assigned), featuring an unusually short and osteologically reinforced facial region. A robust upper temporal arch and prominent surangular ridge indicate the presence of well-developed superficial external adductor musculature, which is divergent relative to pseudosuchians generally. These autapomorphies suggest specialization for a powerful bite. Bayesian and maximum parsimony phylogenetic analyses find E. lacrimosa outside of an H. agilis clade, near the base of Crocodylomorpha. The specializations of E. lacrimosa therefore represent the beginnings of ecological diversification within Crocodylomorpha among animals of a similar size, predating the Late Triassic appearance of Crocodyliformes and the Jurassic radiation of mesoeucrocodylians. Coexistence in the same single-event death assemblage of E. lacrimosa and H. agilis—two small early crocodylomorphs with functionally significant anatomical differences—suggests partitioning of terrestrial carnivorous niches within the ‘sphenosuchian’ grade.

Keywords: Crocodylomorpha, Sphenosuchia, Triassic, Hesperosuchus agilis, phylogenetics

Photographs and line drawings of the skull of Eosphorosuchus lacrimosa as preserved and prepared in right ventrolateral view (a, c) and left dorsolateral view (b, d). Grey shading represents matrix or bones of other individuals; halftone represents areas of breakage.

Abbreviations: an, angular; e, ectopterygoid; f, frontal; j, jugal; l, lacrimal; m, maxilla; n, nasal; pa, prearticular; pb, palpebral; pl, palatine; pm, premaxilla; po, postorbital; pt, pterygoid; sa, surangular; tpt, transverse process of the pterygoid. Scale bar is 2 cm.

 

ARCHOSAURIA Cope, 1869 (Gauthier & Padian [2020])

PSEUDOSUCHIA Zittel, 1887 

CROCODYLOMORPHA Hay, 1930 (emend. Walker [1970])

Eosphorosuchus lacrimosa gen. et sp. nov.

 

 Etymology: Eosphorosuchus derives from ‘Eosphoros,’ one of two Greek gods representing the planet Venus and the counterpart of Hesperos. As Eosphoros was the ‘dawn-bringer’, this name highlights both the dawning of crocodylomorph ecological diversity and the close historic association of this specimen with the genus Hesperosuchus. ‘Suchus’ derives from ‘soukhos’, Greek for crocodile. The specific epithet lacrimosa refers to the distinctive lacrimal region.

 

Miranda Margulis-Ohnuma; Alexander A. Ruebenstahl; Dalton L. Meyer and Bhart-Anjan S. Bhullar. 2026. A Short-snouted ‘sphenosuchian’ with unusual Feeding Anatomy demonstrates that Ecological Specialization occurred early in Crocodylomorph Evolution. Proc Biol Sci . 293 (2069): 20260130. DOI: doi.org/10.1098/rspb.2026.0130 [15 Apr 2026]

[Paleontology • 2026] Ptychotherates bucculentus • A New Taxon of saurischian Dinosaur (Saurischia: Morphoraptor) from the Coelophysis Quarry of New Mexico, USA (Triassic: latest Norian or Rhaetian) highlights herrerasaurian diversity in the latest Triassic

 

Ptychotherates bucculentus 

Srivastava & Nesbitt, 2026

DOI: doi.org/10.1002/spp2.70069 

Abstract

The most complete record of the earliest dinosaur lineages is from the Carnian from the higher latitudes of Pangea (e.g. present-day Brazil, Argentina), but dinosaurian assemblages from the upper stages of the Upper Triassic are better known from the low latitudes of Pangea (present day southwestern USA). How early carnivorous dinosaurian diversity matches or mismatches at various latitudes remains to be documented because of uncertainty around the spatio-temporal ranges and phylogenetic relationships of early dinosaur lineages. We examine low-latitude diversity patterns through the lens of the saurischian dinosaur Tawa hallae and close relatives, including a new species, Ptychotherates bucculentus gen. et sp. nov. The new taxon is known from an incomplete but well-preserved skull (CM 31368) from the uppermost Triassic Coelophysis Quarry in northern New Mexico. The new taxon clearly shares synapomorphies with Tawa hallae, such as distinctive fossae on the quadrate and otoccipital and a dorsoventrally tall and laterally flat jugal. However, the new taxon is distinguishable from all other coeval ornithodirans by a combination of many character states, including the proportionally dorsoventrally deepest jugal known for any Triassic-aged dinosaur. Higher-palaeolatitude ecosystems across Pangea show a complete turnover of carnivorous dinosaurs by neotheropods in the Norian and Rhaetian, but the ‘Chindesaurus–Tawa’ clade (Morphoraptora clade nov.) coexisted with neotheropods possibly until the End-Triassic Extinction Event. This suggests a low-latitude ‘museum’ where early-diverging lineages survived much longer than at higher latitudes, and that the End-Triassic Extinction Event affected dinosaur diversity more than previously hypothesized.

Keywords: biogeography, Saurischia, extinction, skull, phylogenetics, clade longevity

SYSTEMATIC PALAEONTOLOGY

DINOSAURIA Owen 1842 sensu Langer et al. 2020

SAURISCHIA Seeley 1888 sensu Gauthier et al. 2020

Clade MORPHORAPTORA nov.

Derivation of name: Morphe from the Greek for ‘form, shape’ and raptor from the Latin for ‘robber’, describing the morphological convergence between members of this clade and Theropoda, as if this clade is ‘stealing’ morphology. ‘Morphoraptor’ loosely translates to ‘bodysnatcher’, in honour of the 2007 song by Radiohead in the album In Rainbows, which author S. Srivastava listened to hundreds of times while preparing this manuscript.

The posterior portion of the skull Ptychotherates bucculentus (CM 31368) in posterior view.

Abbreviations: ar, articular bo, basioccipital; bt, basituber; f, frontal; fm, foramen magnum; fno, fenestra ovalis; pa, parietal; par, paroccipital process of the otoccipital; mf, metotic foramen; n, nasal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; ptf, posttemporal fenestra; qj, quadratojugal; qu, quadrate; rap, retroarticular process; so, supraoccipital; sq, squamosal; st, stapes. Crossed circle indicates posterior direction out of page. Scale bar represents 1 cm.

Digital reconstruction of the skull of Ptychotherates bucculentus (CM 31368) in left lateral view. Dashed lines indicate extrapolation and the coloured infill indicates known bone presence.

Abbreviations: eaf, external antorbital fenestra; en, external naris; emf, external mandibular fenestra; itf, infratemporal fenestra; orb, orbit. Arrow indicates anterior direction. Scale bar represents 2 cm.

 

Genus Ptychotherates nov.

 

Derivation of name: Ptycho from the Greek for ‘fold’ because of the numerous and challenging axes of reorientation on elements of the holotype. Therates from the Greek for ‘hunter’, for the carnivorous habits inferred from its teeth.

 Ptychotherates bucculentus sp. nov.  

Derivation of name: The species epithet is Latin for ‘with full cheeks’ in reference to the exceptionally tall jugal.

 

Diagnosis: Ptychotherates bucculentus bears the following combination of character states (local autapomorphies indicated with *): supratemporal fossa present on posterior portion of the frontal and dorsal surface of the parietal; tapering dorsal process of the maxilla; maxilla lacking antorbital fossa on its posterior portion ventral to the antorbital fenestra; prefrontal symmetrical in lateral view*; jugal body proportionally dorsoventrally deep* (i.e. more than three times as deep as the jugal posterior process, deeper than the length of postorbital ventral process, and more than half the height of the quadrate main body; Table 1); laterally extensive ventral process (= crista interfenestralis) of the otoccipital; ventral process of squamosal anteroposteriorly wide with a lateral fossa on the posterior part; retroarticular process upturned immediately posterior to glenoid; anterolateral portion of postorbital dorsally overhanging orbit; postorbital dorsolaterally overlapping the squamosal; posttemporal fenestra as wide as foramen magnum; nasal and frontals flat dorsally; serrated and recurved teeth with fine serrations (4–5 per 1 mm in the maxilla, 5–6 per 1 mm in the dentary) with pointed apices of the serrations.

Artistic rendition of Ptychotherates bucculentus.

Artwork by Megan Sodano 

 

Simba Srivastava and Sterling J. Nesbitt. 2026. A New Taxon of saurischian Dinosaur from the Coelophysis Quarry of New Mexico, USA (Triassic: latest Norian or Rhaetian) highlights herrerasaurian diversity in the latest Triassic. Papers in Palaeontology. 12(2); e70069. DOI: doi.org/10.1002/spp2.70069 [14 April 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 • 2026] Polonolimulus zaleziankensis • A New Triassic austrolimulid from Poland presents insight into xiphosurid Evolution and Palaeobiogeography at the Dawn of the Mesozoic

 

Polonolimulus zaleziankensis 

Audycki​, Bicknell, Niedźwiedzki & De Baets, 2026 

 

 DOI: doi.org/10.7717/peerj.20950 

Reconstruction by Jonatan Audycki

Abstract 

Xiphosurids are aquatic chelicerates widely viewed as examples of so-called ‘living fossils’ due to their apparent morphological conservatism and limited diversity since at least the Jurassic. However, earlier representatives were much more diverse and morphologically disparate. Particularly striking are hypertrophied genal spines and reduced thoracetrons of the Triassic austrolimulids, possibly related to their colonization of brackish or freshwater habitats. Here we describe Polonolimulus zaleziankensis gen. et sp. nov., a new austrolimulid genus from the Early Triassic of Holy Cross Mountains, Poland. Geometric morphometric analysis positions the new find among the morphologically most ‘extreme’ austrolimulids, extending the geographic range of those forms to Central Europe. A palaeobiogeographic reconstruction of Triassic xiphosurids reveals their surprisingly wide distribution already in Early Triassic, suggesting either an earlier dispersal in the Late Permian or a rapid diversification in the earliest Triassic. The reconstruction of most austrolimulid occurrences within or proximal to the shallow marine areas casts doubts on the hypothesis they inhabited fully freshwater palaeonvironments, which should be reinvestigated in the future. The new material further adds to the growing understanding of xiphosurid diversity and evolution in the early Mesozoic.

 

Keywords: Limulus, Horseshoe crab, Arthropoda, Buntsandstein, Holy Cross Mountains

Polonolimulus zaleziankensis gen. et sp. nov. 
The rock slab bearing Muz. PGI 1808.II.10 and another xiphosurid fossil.
(A) The upper surface of the rock slab with Muz. PGI 1808.II.10 preserved as a concave natural mould. (B) The lower surface of the rock slab with the uncertain convex horseshoe crab-shaped structure, considered a possible trace fossil (see ‘Remarks’ for further discussion).
(C) Close-up of Muz. PGI 1808.II.10 (D) Close-up of the convex structure on the lower surface coated with ammonium chloride sublimate. Scale bars: (A, B) 50 mm, (C, D) 20 mm. Photo credit: Jonatan Audycki.

Polonolimulus zaleziankensis gen. et sp. nov.

Idealized reconstruction of Polonolimulus zaleziankensis gen. et sp. nov.

Reconstruction by Jonatan Audycki.

Palaeobiogeography of Triassic horseshoe crabs. Palaeogeography of the world is reconstructed at 245 Ma (Anisian, Middle Triassic) and displayed using Mollweide projection, with a close-up of the Central European Basin System. The extents of shallow seas (light blue), landmasses (pale yellow) and mountain ranges (orange) are reconstructed based on Cao et al. (2017). Symbols represent Triassic localities that have yielded horseshoe crab fossils, their ages, and taxonomic assignment. The palaecoordinates of the xiphosurid localities are also reconstructed at 245 Ma for consistency. Simplified reconstructions of austrolimulids are displayed for context and comparison: 1–Polonolimulus zaleziankensis from the Lower Triassic (uppermost Induan/lowermost Olenekian) Zalezianka-Gózd locality, Poland; 2–Psammolimulus gottingensis from the Lower Triassic (Olenekian) Solling Formation, Germany; 3–Batracholimulus fuchsbergensis from the Upper Triassic (Norian/Rhaetian boundary) Exter Formation, Germany; 4–Attenborolimulus superspinosus from the Lower Triassic (upper Olenekian) Petropavlovka Formation, Russia; 5–Vaderlimulus tricki from the Lower Triassic (lower Spathian, Olenekian) Thaynes Group, USA; 6–Austrolimulus fletcheri from the Middle Triassic (lower Anisian) Beacon Hill Quarry, Hawkesbury Sandstone, Australia; 7–Dubbolimulus peetae from the Middle Triassic (lower Anisian) Ballimore Formation, Australia; 8–Tasmaniolimulus patersoni from the Lower Triassic (lower Induan) Jackey Shale, Tasmania (Australia). Since the investigated xiphosurid localities differ stratigraphically, their geographical position relative to continental boundaries and shallow seashores are approximated. The display window on the map showing close-up boundaries is not square due to employed map projection.

 

Jonatan Audycki​, Russell D.C. Bicknell, Grzegorz Niedźwiedzki, Kenneth De Baets. 2026.  2026. A New Triassic austrolimulid from Poland presents insight into xiphosurid Evolution and Palaeobiogeography at the Dawn of the Mesozoic. PeerJ. 14:e20950. DOI: doi.org/10.7717/peerj.20950 [2026-03-25]

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