[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]

 x.com/AnatRecord/status/1751938238858854832

[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] Galahadosuchus jonesi • A Second Species of non-crocodyliform Crocodylomorph from the Late Triassic fissure deposits of southwestern UK: Implications for locomotory ecological diversity in Saltoposuchidae

 

 Galahadosuchus jonesi 

Bodenham, Spiekman, Maidment, Upchurch & Mannion, 2026

DOI: doi.org/10.1002/ar.70162

Artwork by M. Dempsey. facebook.com/MEDPalaeo

Abstract

The Late Triassic–Early Jurassic fissures of the Bristol Channel area (southwest England and south Wales) are renowned for their diverse vertebrate faunas. These assemblages have yielded an array of predominantly small-bodied forms that are crucial to our understanding of the early evolution of several major tetrapod clades. Although their dating remains contentious, these deposits provide a valuable insight into biodiversity at a key time in Earth history, given that they span the end-Triassic mass extinction. One of these fissure-fill taxa, Terrestrisuchus gracilis, represents one of the most completely preserved early-branching crocodylomorphs. This species currently occurs exclusively in Late Triassic deposits within the Pant-y-Ffynnon Quarry, whereas only generically indeterminate crocodylomorph remains have been recorded from other fissures in the Bristol Channel area to date. Here we present a detailed anatomical description of a specimen previously assigned to Terrestrisuchus sp. (NHMUK PV R 10002), which comprises the semi-articulated partial postcranial skeleton of a crocodylomorph from the Late Triassic fissure deposits of Cromhall Quarry in the Bristol Channel area. We incorporated NHMUK PV R 10002 into a pre-existing data matrix comprising 39 other operational taxonomic units scored for 138 morphological characters. Phylogenetic analysis under Maximum Parsimony recovers NHMUK PV R 10002 as the sister taxon to Terrestrisuchus, clustering in all cases with the contemporaneous German species Saltoposuchus connectens to form the non-crocodyliform crocodylomorph clade Saltoposuchidae. Under equal and extended implied weights, the Early Jurassic South African species Litargosuchus leptorhynchus and the Late Triassic US species Hesperosuchus agilis, respectively, are additional saltoposuchids. Although NHMUK PV R 10002 exhibits a high degree of morphological similarity to Terrestrisuchus, key differences are evident in the morphology of the dorsal vertebrae, fore- and hindlimb long bones, proximal carpals, metacarpals, and calcaneum. We therefore designate NHMUK PV R 10002 as the holotype of Galahadosuchus jonesi n. gen. n. sp. Several anatomical features indicate that Galahadosuchus was a highly gracile, cursorial terrestrial quadruped with an erect stance, including: elongate proximal carpals; long, slender, and tightly bunched metacarpals; development of a distinct, medially directed femoral head; and a classical crurotarsal ankle joint configuration. A similar stance is also reconstructed for Terrestrisuchus; however, some of the anatomical differences between these two taxa, including the relative proportions and morphology of limb and carpal bones, might correspond to differences in locomotory function, potentially reflecting varying specializations within early-branching crocodylomorphs.

Block A of NHMUK PV R 10002, the holotype of  Galahadosuchus jonesi n. gen. n. sp. 
(a) Photograph of block A in plan view. (b) Line drawing of the elements visible on block A in plan view. Elements visible on the right-hand side of the block (colored hues) are assigned to Galahadosuchus jonesi; elements on the left-hand side of the block (shades of gray) are identified as indeterminate remains of a rhynchocephalian.

as, astragalus; ca, calcaneum; cd, caudal vertebra; ch, chevron; dc, distal carpal; dors, dorsal vertebra; fe, femur; ga, gastralia; ibf, indeterminate bone fragment; is, ischium; mc, metacarpal; mph, manual phalanx; mt, metatarsal; os, osteoderm; pph, pedal phalanx; pu, pubis; ra, radiale; rd, radius; ti, tibia; ul, ulna; ulr, ulnare. Scale bar represents 100 mm.

Archosauria Cope, 1869–1870 (sensu Gauthier & Padian, 2020).

Crocodylomorpha (Hay, 1930, sensu Nesbitt, 2011).

Saltoposuchidae (Crush, 1984, sensu Spiekman, 2023).

Galahadosuchus gen. nov.

Etymology. “Galahad” from Arthurian legend, a knight renowned for his moral uprightness; combined with “suchus” from the Greek for crocodile. The genus name alludes to the upright posture of the taxon, playing on the dual sense of “upright” as both moral and physical.

 

Galahadosuchus jonesi, sp. nov.

Etymology. The species epithet honors David Rhys Jones, a teacher at Ysgol Uwchradd Aberteifi, in recognition of his work inspiring students at the school (including EHB) to pursue their passion for science.

Life reconstruction of Galahadosuchus jonesi n. gen. n. sp.
 The morphology of regions of the body that are not currently known for Galahadosuchus jonesi (i.e., not preserved in NHMUK PV R 10002) is inferred from comparison with Terrestrisuchus gracilis (Spiekman et al., 2023, 2024) due to the high degree of morphological similarity between these two taxa. Scale bar represents 100 mm.

Artwork by M. Dempsey. facebook.com/MEDPalaeo

Ewan H. Bodenham, Stephan N. F. Spiekman, Susannah C. R. Maidment, Paul Upchurch, Philip D. Mannion. 2026. A Second Species of non-crocodyliform Crocodylomorph from the Late Triassic fissure deposits of southwestern UK: Implications for locomotory ecological diversity in Saltoposuchidae. The Anatomical Record. DOI: doi.org/10.1002/ar.70162 [12 February 2026]

 facebook.com/MEDPalaeo/posts/4294410500770752

[Paleontology • 2025] The coelurosaur theropods of the Romualdo Formation, early Cretaceous (Aptian) of Brazil: Santanaraptor placidus meets Mirischia asymmetrica

Hypothetical reconstruction of Mirischia asymmetrica (left) and Santanaraptor placidus (right) disputing a lizard in what is now northeastern Brazil ~112 million years ago (Early Cretaceous, Aptian).

Santanaraptor placidus Kellner, 1999 
Mirischia asymmetrica Naish, Martill & Frey, 2004

in Delcourt, Grillo, Hendrickx, Kellermann et Langer, 2025.

 Santanaraptor   Mirischia 

DOI: doi.org/10.1002/ar.70085 

Illustration by Guilherme Gehr. 

 

Abstract

The upper carbonate concretion levels of the Romualdo Formation (Aptian, Brazil) have yielded several theropod dinosaur remains, including spinosaurids and the coelurosaurs Santanaraptor placidus and Mirischia asymmetrica, the phylogenetic affinities of which are controversial. Here, we present a comprehensive anatomical reassessment of the holotypes of both species (MN 4802-V and SMNK 2349 PAL, respectively), integrating newly observed osteological features and a detailed comparison of the pelvic and hind limb elements. Our preferred phylogenetic hypothesis places S. placidus and M. asymmetrica in the earliest-branching maniraptoromorph clade, along with Juratyrant langhami and Tanycolagreus topwilsoni from the Late Jurassic of Laurasia, suggesting an early diversification of coelurosaurs in that area, followed by Early Cretaceous dispersal events towards Gondwana. The comparative analysis of the two Romualdo taxa refutes their synonymy, given consistent differences in ischial (position and shape of the obturator plate and foramen) and tibial (condylar configuration) morphology. The observed morphological variation in the ischial obturator plate across early coelurosaurs further highlights a significant degree of homoplasy in this structure during the early radiation of the group. This revision underscores the need for additional research to further resolve the early evolutionary history of coelurosaur theropods.

Keywords: Araripe, Coelurosauria, Dinosauria, Gondwana, Theropoda

Hypothetical reconstruction of Mirischia asymmetrica (left) and Santanaraptor placidus (right) disputing a lizard in what is now northeastern Brazil ~112 million years ago (Early Cretaceous, Aptian).

Illustration by Guilherme Gehr. 

Santanaraptor placidus Kellner, 1999

Mirischia asymmetrica Naish, Martill & Frey, 2004

CONCLUSIONS: 

The comprehensive reassessment of Santanaraptor placidus (MN 4802-V) and Mirischia asymmetrica (SMNK 2349) presented here offers new insights into the anatomy, taxonomy, and phylogenetic affinities of these two coelurosaur theropods from the Early Cretaceous (Aptian) Romualdo Formation of Brazil. Despite the minor overlapping of skeletal elements, both specimens exhibit consistent anatomical differences that support their recognition as distinct species. These differences are particularly evident in the configuration of the ischial obturator plate and the structure of the proximal tibial condyles.

Some of our phylogenetic results place S. placidus and M. asymmetrica together with Juratyrant langhami and Tanycolagreus topwilsoni, from the Late Jurassic of Laurasia, in a clade of early branching maniraptoromorphs. This is the first time that these Brazilian taxa are found closely related within a lesser-inclusive clade, corroborating previous assumptions of close biogeographic relations between Laurasian and Gondwanan landmasses by the Early Cretaceous. Further biogeographic patterns are, however, harder to define, especially having in mind the still patchy record of Jurassic theropods in areas such as Africa, Australia, India, Antarctica, and South America.

 

Rafael Delcourt, Orlando Nelson Grillo, Christophe Hendrickx, Maximilian Kellermann, Max Cardoso Langer. 2025. The coelurosaur theropods of the Romualdo Formation, early Cretaceous (Aptian) of Brazil: Santanaraptor placidus meets Mirischia asymmetrica. The Anatomical Record. DOI: doi.org/10.1002/ar.70085 [18 November 2025]

[Paleontology • 2025] The Osteology, Taxonomy, and Phylogenetic Placement of Seeleyosaurus guilelmiimperatoris (Plesiosauroidea: Microcleididae) from the Lower Jurassic Posidonia Shale of Germany

 

Seeleyosaurus guilelmiimperatoris (Dames, 1895) 

Sachs, Madzia, Marx, Roberts, Hampe et Kear, 2025. 

 DOI: doi.org/10.1002/ar.25620 

Researchgate.net/publication/389208223

Abstract

Seeleyosaurus guilelmiimperatoris is an early-diverging plesiosauroid from the lower Toarcian (Lower Jurassic) of the Posidonienschiefer Formation (Posidonia Shale) of Holzmaden, southwestern Germany. It is known from almost complete skeletons of two osteologically mature individuals, the holotype and a referred specimen that was largely destroyed during World War II. Although well-preserved and substantially complete, the anatomy of Seeleyosaurus and its taxonomic and phylogenetic significance remain insufficiently understood. Here, we provide a complete osteological description of the taxon. Seeleyosaurus guilelmiimperatoris can be diagnosed based on a unique combination of characters, including one autapomorphy: the tall and basally constricted neural spines of the posterior cervical, pectoral, and dorsal vertebrae which have a sinusoidal shape in lateral view. Our study supports the validity of the plesiosauroid taxon Plesiopterys wildi, which was considered a junior synonym of Seeleyosaurus in a previous joint assessment of the taxa. Our phylogenetic evaluation places S. guilelmiimperatoris among Microcleididae, in congruence with previous studies. However, in contrast to earlier phylogenetic reconstructions, our analyses, which take into account numerous changes to the character matrix, reconstruct S. guilelmiimperatoris as falling within the Microcleidus clade. While we admit that Seeleyosaurus might potentially be considered a species of Microcleidus, we refrain from promoting this nomenclatural change pending an osteological and taxonomic reassessment of Microcleidus spp. as well as other, potentially closely related forms, such as Lusonectes sauvagei.

Keywords: Plesiosauria, Microcleididae, Seeleyosaurus, Toarcian, Lower Jurassic, Germany

Skeleton of the referred specimen of Seeleyosaurus guilelmiimperatoris (SMNS 12039). (a) initial slab mount with original skull and unaltered paddles (from Fraas, 1910a, plate 6). (b) cast of the modified skeleton with modeled skull and arranged paddles (SMNS collection). Scale equals 50 cm.

Seeleyosaurus (left) and Thaumatosaurus, now Meyerasaurus (right)

as depicted in Water reptiles of the past and present (1914)

Sven Sachs, Daniel Madzia, Miguel Marx, Aubrey J. Roberts, Oliver Hampe and Benjamin P. Kear. 2025. The Osteology, Taxonomy, and Phylogenetic Placement of Seeleyosaurus guilelmiimperatoris (Plesiosauroidea, Microcleididae) from the Lower Jurassic Posidonia Shale of Germany. The Anatomical Record. DOI: doi.org/10.1002/ar.25620 [21 February 2025]

 Researchgate.net/publication/389208223_The_osteology_taxonomy_and_phylogenetic_placement_of_Seeleyosaurus_from_the_Lower_Jurassic_Posidonia_Shale_of_Germany

[PaleoMammalogy • 2024] Exposed Weapons: A Revised Reconstruction of the Facial Anatomy and Life Appearance of the Saber-toothed Cat Megantereon (Felidae: Machairodontinae)

 

Reconstruction of the external appearance of the head of Megantereon in different angles and with different facial expressions

in Antón, Siliceo, Pastor, Jiangzuo et Salesa, 2024.

DOI: doi.org/10.1002/ar.25622 

  facebook.com: Mauricio Anton 

x.com/AnatRecord

Abstract

Megantereon was a widespread saber-toothed felid from the Pliocene and Pleistocene of the Old World and North America, but its rarity in the fossil record makes it complicated to restore its life appearance. Lack of complete specimens makes it necessary to combine information from fossils of different individuals to reconstruct their facial anatomy. In this work, we combine the analysis of skulls and mandibles of Megantereon from various fossil sites with the study of extant carnivorans through dissection, 3D scans, and the observation of live individuals. Megantereon combined very elongated upper canines with mandibular flanges that were not deep enough to match the length of the sabers, as well as a wide maxilla combined with narrow incisor rows and mandibular symphysis. Such features are compatible with the presence of exposed canines in life, because the narrow symphysis allows room to accommodate lips and other soft tissues medial to the sabers, while the protrusion of the tips of the upper canines beyond the mental flanges makes it unlikely that they would be enveloped in soft tissue sheaths, which would dangle with the inherent risk of puncture. Megantereon was transitional between saber-toothed felids with covered upper canines, where saber length fits with mental flange depth, and the derived Smilodon where the upper canines are much longer than the flanges and the lips fit between upper canines and mandible, leaving the upper canine crowns largely exposed in life.

Keywords: anatomy, muscles, Paleobiology, Smilodontini

Sequential reconstruction of the head of Megantereon:
 (a) skull and mandible; (b) deep muscles and other structures; (c) superficial muscles; and (d) reconstructed external appearance.

md, m. digastricus; ml, m. levator nasolabialis; mm, m. masseter; mo, m. orbicularis oris; mp, mystacial pad; mt, m. temporalis; mz, m. zygomaticus; nc, nasal cartilage; orl, outer rim of lower lip; p, platysma; pct, pad of connective tissue; tfl, tongue-like flap of lower lip.

Reconstruction of the external appearance of the head of Megantereon in different angles and with different facial expressions:
 (a) skull and reconstructed head with relaxed mouth in lateral view; (b) skull and reconstructed head with closed mouth in frontal view; (c) skull and reconstructed head with relaxed mouth in frontal view; (d) skull and reconstructed head with relaxed mouth in perspective view; and (e) skull and reconstructed head in perspective view, yawning.

Mauricio Antón, Gema Siliceo, Juan Francisco Pastor, Qigao Jiangzuo and Manuel J. Salesa. 2024. Exposed Weapons: A Revised Reconstruction of the Facial Anatomy and Life Appearance of the Saber-toothed Cat Megantereon (Felidae, Machairodontinae). The Anatomical Record. DOI: doi.org/10.1002/ar.25622 

  facebook.com/MauricioAnton3/posts/10223383237603906

 x.com/AnatRecord/status/1874520968074506412

[Paleontology • 2024] Reassessment of Xenodens calminechari with A Discussion of Tooth Morphology in Mosasaurs

 

 Xenodens calminechari be considered a nomen dubium

in Sharpe, Powers et Caldwell, 2024. 

DOI: doi.org/10.1002/ar.25612 

  x.com/Paleoartologist

Abstract

Xenodens calminechari is a mosasaurid taxon named by Longrich et al. (2021) based on the holotype MHNM.KH.331, a left maxilla with several teeth. This holotype was obtained nonscientifically (without technical supervision) from an area in Morocco that yields many manipulated or forged specimens. Examination of Longrich et al. (2021) reveals four tooth crowns occupy what appear to be two alveoli in MHNM.KH.331, and there is potential adhesive connecting the tooth crowns to the maxilla on their lateral sides. We argue that the articulated tooth crowns of this taxon were artificially placed in the maxilla, rendering at least two apomorphies of this taxon the product of forgery. Longrich et al. (2021)'s claims of fused tooth ‘roots' in MNHM.KH.331 are instead calcified periodontal ligament and alveolar bone that have ankylosed, resembling the typical mosasaurid condition. Differing tooth crown morphology does not preclude the referral of the teeth of this specimen to a younger ontogenetic stage of another mosasaur (possibly Carinodens) because many extant lizard species show drastic ontogenetic changes in the dentition. We argue that Xenodens calminechari represents a nomen dubium. This specimen constitutes a confluence of two persistent problems in vertebrate paleontology: material sourced from commercial excavations that has not been adequately tested for forgery, and taxa named from tooth-based holotypes that ignore the potential for intraspecific dental variation and interspecific convergence in dental characters, as are common in squamates. We suggest that Longrich et al. CT scan MHNM.KH.331, and we supply CT examples for identifying artificially added tooth crowns to Moroccan mosasaur jaws. Finally, we provide recommendations for the designation of mosasaurid holotypes.

Keywords: dentition, mosasaur, paleontology, squamate, taxonomy

(a) MHNM.KH.331, holotype of Xenodens calminechari in lateral view in matrix, photograph adapted from Longrich et al., 2021; (b) fake mosasaurid jaw (UALVP unlisted) from Morocco showing tooth crowns artificially attached to unrelated bone fragments, ‘in matrix’; (b) close-up of tooth crowns in lateral view of MHNM.KH.331, photograph adapted from Longrich et al. (2021); (d) close-up of (c) showing tooth crown-‘jaw’ intersection; (e) close-up of Halisaurus arambourgi UALVP 56123 showing forged tooth-jaw intersection.

Left maxilla of Xenodens calminechari, MHNM.KH.331: All photographs adapted from Longrich et al. (2021). (a) Maxilla in ventral view, showing irregular proposed tooth spacing in posterior tooth row; (b) close-up of (a) showing nonfusion of tooth roots due to separation of alveoli (marked by asterisks) by alveolar bone; (c) maxilla in medial view showing a disjunct arrangement of tooth crowns and resorption pits (which indicate alveolar spacing); (d) close-up of tooth crowns in medial view showing the irregular junction of tooth crowns and basal tissue; (e) close-up of tooth crowns in lateral view showing potential adhesive connecting tooth crowns to maxilla.

CT scan example for recognizing falsely attached teeth in mosasaur fossils from Morocco. (a, b) Anterior portion of left dentary of Halisaurus arambourgi UALVP 56123 from type locality of Xenodens calminechari

Issues with tooth-based holotypes in vertebrate paleontology, using three hypothetical species of mosasaurids as an example. Holotype 1 was established using an anterior adult tooth of species 2, and holotype 2 was established using a juvenile posterior tooth from species 1. Neither holotype adequately represents the anatomy of its target taxon.

Henry S. Sharpe, Mark J. Powers and Michael W. Caldwell. 2024. Reassessment of Xenodens calminechari with A Discussion of Tooth Morphology in Mosasaurs. The Anatomical Record. DOI: doi.org/10.1002/ar.25612 

  x.com/Paleoartologist/status/1869006641993335019

[Paleontology • 2024] Cranial Anatomy of Acynodon adriaticus and extreme durophagous adaptations in Eusuchia (Reptilia: Crocodylomorpha)

 

Acynodon adriaticus Delfino, Martin & Buffetaut, 2008

in Muscioni, Chiarenza, Fernandez, Dreossi, Bacchia et Fanti. 2024.   

DOI: doi.org/10.1002/ar.25574

  facebook.com/AnatomicalRecord

Artwork by Davide Bonadonna   facebook.com/DavideBonadonna1

Abstract

Acynodon adriaticus, a small eusuchian from the Late Cretaceous of Italy, is known for its well-preserved cranial and postcranial material. Despite its excellent preservation, many details remain hidden due to the physical overlap between the elements and matrix obliteration. We used Micro-CT scans to reveal previously overlooked anatomical features and describe in detail the cranial and dental anatomy of this taxon, shedding new light on its palaeoecology. The holotypic specimen, SC 57248, represents a mature individual exhibiting signs of hyperossification, developed ornamentation, and various pathologies, including jaw arthritis and a possible dental anomaly. Acynodon adriaticus exhibits significant durophagous adaptations, including a robust, brevirostrine skull optimized for powerful biting and stress-load capacity. Its specialized dentition, lacking caniniform teeth, features anterior chisel-like teeth and hypertrophic posterior molariforms with thick enamel, indicative of a diet specializing in hard-shelled prey. The dentition pattern, accelerated molariform replacement rate, and reduced orbit size suggest adaptations for durophagous foraging in turbid, densely vegetated aquatic environments. The paleoecological context during the Late Cretaceous, characterized by increased freshwater habitats and high invertebrate diversity, likely facilitated the evolution of such specialized traits in A. adriaticus. This small crocodylomorph likely foraged slowly in shallow, benthic environments, using its powerful bite to process mollusks and large arthropods. The study of A. adriaticus, along with comparisons with other crocodylomorphs and ecomorphologically similar taxa like Iharkutosuchus makadii and Gnatusuchus pebasensis, provides a valuable morphofunctional model for understanding the evolutionary pathways of extinct crocodylians to durophagy.

Keywords: Acynodon, Cretaceous, durophagy, Hylaeochampsidae, paleobiology

  Systematic paleontology

Crocodylomorpha Hay, 1930 sensu Nesbitt, 2011.

Neosuchia Benton & Clark, 1988.

Eusuchia Huxley, 1875 sensu Brochu, 2003.

Hylaeochampsidae Andrews, 1913.

Acynodon Buscalioni et al., 1997.

Acynodon adriaticus Delfino et al., 2008.

Schematic individual cranial bones of MCSNT 57248 in dorsal (a), ventral (b), lateral (c) and posterior (d) view. ...

 

Marco Muscioni, Alfio Alessandro Chiarenza, Diego Bladimir Haro Fernandez, Diego Dreossi, Flavio Bacchia, Federico Fanti. 2024. Cranial Anatomy of Acynodon adriaticus and extreme durophagous adaptations in Eusuchia (Reptilia: Crocodylomorpha). The Anatomical Record. DOI: doi.org/10.1002/ar.25574

  facebook.com/AnatomicalRecord/posts/1042639271202269

  facebook.com/DavideBonadonna1/posts/1077033717762273

Nuove scoperte sul fossile di un coccodrillo di 80 milioni di anni al Villaggio del Pescatore

 www.nationalgeographic.it/nuove-scoperte-sul-fossile-di-un-coccodrillo-di-80-milioni-di-anni-al-villaggio-del-pescatore

[Paleontology • 2024] Epoidesuchus tavaresae • A new Peirosauridae (Crocodyliformes: Notosuchia) from the Adamantina Formation (Bauru Group, Late Cretaceous), with a revised phylogenetic analysis of Sebecia

Epoidesuchus tavaresae

Ruiz, Queiroz, Martins, Godoy, Iori, Langer, Montefeltro & Bronzati, 2024

 

DOI: 10.1002/ar.25559 

x.com/PedroLGodoy 

 Artwork by Guilherme Gehr

Abstract

Peirosauridae (Crocodyliformes, Notosuchia) is one of the fossil lineages of crocodyliforms ubiquitous in the Cretaceous deposits of the Bauru Basin. Here, we describe a new species of a longirostrine Peirosauridae from the Adamantina Formation (Bauru Basin, Late Cretaceous). The specimen consists of a partially preserved skull with a cranial roof, interorbital region, and fragments of the posterior portion of the rostrum, including the prefrontal and lacrimal; left hemimandible, with 14 alveoli and 12 teeth; and a single cervical rib fragment. The specimen is associated with Peirosauridae by three cranial synapomorphies, and it can be assigned to a new genus and species by presenting seven cranial and one tooth apomorphies. To clarify the position of the new taxon, an updated phylogenetic analysis was performed with increased sampling of taxa of Notosuchia, especially Peirosauridae, and phylogenetically relevant characters. Our results indicated the monophyly of Peirosauridae, formed by two main lineages, the oreinirostral and presumably terrestrial Peirosaurinae and the longirostrine and presumably semi-aquatic Pepesuchinae. The recovering of both lineages as distinct entities was also reinforced through a morphospace analysis. Pepesuchinae were notable by exploring a position of the morphospace not explored by any other Notosuchia. Their longer rostra and the assumption of them being gradually specialized to aquatic habits reflects the unique diversity of these crocodyliforms through the Cretaceous deposits of South America and Africa.

Keywords: Bauru Basin, freshwater Tetrapoda, Mesoeucrocodylia, Pepesuchinae, South America

Epoidesuchus tavaresae, from the Adamantina Formation (Late Cretaceous), a new pepesuchine peirosaurid, which was long-snouted and semiaquiatic.

  paleoart by Guilherme Gehr

 Juan V. Ruiz, Marcos V. L. Queiroz, Kawan C. Martins, Pedro L. Godoy, Fabiano V. Iori, Max C. Langer, Felipe C. Montefeltro and Mario Bronzati. 2024. A new Peirosauridae (Crocodyliformes, Notosuchia) from the Adamantina Formation (Bauru Group, Late Cretaceous), with a revised phylogenetic analysis of Sebecia. The Anatomical Record. DOI: doi.org/10.1002/ar.25559 

 x.com/PedroLGodoy/status/1829467655188689194

Graphical Abstract: This study presents a new species of Peirosauridae, Epoidesuchus tavaresae, from the Adamantina Formation, Cretaceous of Brazil. In the most complete phylogenetic analysis of this lineage conducted to date, Peirosauridae was recovered encompassing two main lineages, Peirosaurinae (usually orenirostrine forms) and Pepesuchinae (usually longirostrine forms). 

[Paleontology • 2024] Cranial Anatomy and Phylogenetic Affinities of Bolosaurus major, with new information on the unique bolosaurid feeding apparatus and evolution of the impedance-matching ear

Bolosaurus major

in Jenkins, Foster, Napoli, Meyer, Bever et Bhullar, 2024. 

DOI: doi.org/10.1002/ar.25546 

  x.com/reptiliferous

Abstract

Resolving the phylogenetic relationships of early amniotes, in particular stem reptiles, remains a difficult problem. Three-dimensional morphological analysis of well-preserved stem-reptile specimens can reveal important anatomical data and clarify regions of phylogeny. Here, we present the first thorough description of the unusual early Permian stem reptile Bolosaurus major, including the first comprehensive description of a bolosaurid braincase. We describe previously obscured details of the palate, allowing for insight into bolosaurid feeding mechanics. Aspects of the rostrum, palate, mandible, and neurocranium suggest that B. major had a particularly strong bite. We additionally found B. major has a surprisingly slender stapes, similar to that of the middle Permian stem reptile Macroleter poezicus, which may suggest enhanced hearing abilities compared to other Paleozoic amniotes (e.g., captorhinids). We incorporated our new anatomical information into a large phylogenetic matrix (150 OTUs, 590 characters) to explore the relationship of Bolosauridae among stem reptiles. Our analyses generally recovered a paraphyletic “Parareptilia,” and found Bolosauridae to diverge after Captorhinidae + Araeoscelidia. We also included B. major within a smaller matrix (10 OTUs, 27 characters) designed to explore the interrelationships of Bolosauridae and found all species of Bolosaurus to be monophyletic. While reptile relationships still require further investigation, our phylogeny suggests repeated evolution of impedance-matching ears in Paleozoic stem reptiles.

Keywords: amniote, fossil, hearing, Paleozoic, reptile

 

Kelsey M. Jenkins, William Foster, James G. Napoli, Dalton L. Meyer, Gabriel S. Bever and Bhart-Anjan S. Bhullar. 2024. Cranial Anatomy and Phylogenetic Affinities of Bolosaurus major, with new information on the unique bolosaurid feeding apparatus and evolution of the impedance-matching ear. The Anatomical Record. DOI: doi.org/10.1002/ar.25546 

  x.com/reptiliferous/status/1817907322481426897

  x.com/AnatRecord/status/1817960743381471239

[Paleontology • 2024] Fona herzogae • A New semi-fossorial thescelosaurine Dinosaur (Neornithischia: Thescelosauridae) from the Cenomanian-age Mussentuchit Member of the Cedar Mountain Formation, Utah

Fona herzogae

Avrahami, Makovicky, Tucker & Zanno, 2024

 

DOI: 10.1002/ar.25505

Abstract

Thescelosaurines are a group of early diverging, ornithischian dinosaurs notable for their conservative bauplans and mosaic of primitive features. Although abundant within the latest Cretaceous ecosystems of North America, their record is poor to absent in earlier assemblages, leaving a large gap in our understanding of their evolution, origins, and ecological roles. Here we report a new small bodied thescelosaurine—Fona herzogae gen. et sp. nov.—from the Mussentuchit Member of the Cedar Mountain Formation, Utah, USA. Fona herzogae is represented by multiple individuals, representing one of the most comprehensive skeletal assemblages of a small bodied, early diverging ornithischian described from North America to date. Phylogenetic analysis recovers Fona as the earliest member of Thescelosaurinae, minimally containing Oryctodromeus, and all three species of Thescelosaurus, revealing the clade was well-established in North America by as early as the Cenomanian, and distinct from, yet continental cohabitants with, their sister clade, Orodrominae. To date, orodromines and thescelosaurines have not been found together within a single North American ecosystem, suggesting different habitat preferences or competitive exclusion. Osteological observations reveal extensive intraspecific variation across cranial and postcranial elements, and a number of anatomical similarities with Oryctodromeus, suggesting a shared semi-fossorial lifestyle.

SYSTEMATIC PALEONTOLOGY

DINOSAURIA Owen (1842).

ORNITHISCHIA Seeley (1887).

NEORNITHISCHIA Cooper, 1985 (sensu Butler et al., 2008).

ORNITHOPODA Marsh, 1881 (sensu Butler et al., 2008).

THESCELOSAURIDAE (Sternberg, 1937). 

THESCELOSAURINAE (Sternberg, 1940).

THESCELOSAURINAE indet.

Fona herzogae sp. nov.

  Holotype: NCSM 33548, a single partially articulated, nearly complete skeleton. 

 Occurrence: NCSM 33548 was recovered from the Karmic Orodromine locality (UT-16-07-22-Z1), lower Mussentuchit Member, upper Cedar Mountain Formation, Emery County, Utah, USA (Figure 1). Stratigraphic occurrence is between MAZ1 and Last Chance Sandstone (99.466 + 0.046/−0.053 Ma; Tucker et al., 2023) making it the only locality definitively preserving F. herzogae from the lower Mussentuchit unit to date. Mini Troll (NCPALEOUT16) is the geologically youngest locality, emplaced below MAZ3, with an age of 99.231 + 0.090/−0.052 Ma. FMNH PR 4581 was preserved at the Manolo site (UT130831), (99.411 + 0.056/−0.061 Ma) above MAZ2 in the upper Mussentuchit (Figure 1).

Age data is based on a Bayesian age stratigraphic model (Trayler et al., 2020) of the member originally detailed in Tucker et al. (2023). Materials referable to Fona span the lower to upper Mussentuchit Member of the Cedar Mountain Formation, a range of, at minimum, 235,000 kyr. UT-16-07-22-Z1 and NCPALEOUT16 are located on land administered by the US Bureau of Land Management, respectively; exact locality information is restricted by federal statute and is available to qualified researchers via the NCSM.

  DIAGNOSIS: Fona herzogae is a small-bodied, early diverging ornithischian with the following unique combination of characters (autapomorphies are denoted with an asterisk) (Figure 5) *(1) a rostral maxillary fossa located caudal to the first tooth position (unknown in Oryctodromeus and possibly shared by Isaberrysaura and Haya); *(2) an otoccipital that bears a dorsoventrally elongate fossa on the medial surface of the occipital condyle located directly caudal to the medial opening of CN XII; *(3) a rostrocaudally oriented ventral canal on the prootic; *(4) The dorsal margin of the axis neural spine is parallel with the dorsal suture of the centrum, forming an angle of essentially ~0°. *(5) Ischial shaft has bulbous thickening along the dorsal margin directly distal to the obturator process (prominent on both ischia of at least two individuals and weakly present on only the right of another.) (6) base of the prepubic process bears a prominent lateral swelling (possibly present but significantly reduced in Oryctodromeus and Th. neglectus). (7) the caudoventral prong of the jugal's caudal process underlaps a groove along the ventral margin of the quadratojugal (shared by Th. neglectus, likely Changmiania, and possibly at least one specimen of Jeholosaurus [STMN 23–17]). (8) dentary teeth with vertical wear facets on the labial surface that terminate abruptly near the crown base to form a mesiodistally inclined shelf (shared by Oryctodromeus). (9) A low, round tuberosity on the medial side of the scapula located directly opposite to the glenoid ridge (shared with Oryctodromeus and possibly Iani smithi). Standard skeletal measurements of NCSM 33548 are provided in Table 1. Characters 7–9 serve as important synapomorphies that help place Fona within Thescelosaurinae.

Fona n. gen.

  Etymology: Fona (/Foat'NAH/) from the Austronesian language Finoʼ CHamoru. The ancestral maga'håga of the CHamoru people is Fo'na whose name can be translated as ‘the origin’. With her brother Pontan, whose name can be translated as ‘a ripe coconut’, they became the first paramount female and male chiefs (the ancestral maga'låhi of the CHamoru people), ancestrally venerated according to CHamoru tradition (Borja-Quichocho-Calvo, 2021; Cruz, 2022). According to oral history and legend, when Pontan's spirit began to perish and die, Fo'na discovers her powers and uses them to craft parts of Pontan's body into the pieces of the universe. His eyes were turned into the sun and moon, his eyebrows became the rainbows, his back the earth, his chest the sky, his blood the ocean, and from his stomach and penis the mountains and the sacred Creation Point stone pillar were born (Duhaylonsod & Cepeda, 2022). Fo'na had such sorrow from the loss of her brother that her tears flowed down his body to form the currents of the sea, and in reverence to her brother's dream, she decided to bring life to the universe, throwing herself into the earth where her body turned to stone. From her fossilized body sprang forth the first people at Fuha Rock, imbued with her good spirit (Cepeda, 2021; Cunningham, 1992; Perez, 2019; Perez, 2021). This ancestral story of the CHamoru people mirrors the life and death of the thescelosaurine dinosaurs at the Mini Troll locality, as there were at least two subadult individuals that may have been male and female, or perhaps siblings. Additionally, their bodies fell into the earth where they too fossilized. This naming, rooted in the story of Pontan's sacrifice and Fo'na's love for her brother, highlights the CHamoru values of inafa'måolek (to make good for all), geftåo (the need for compassion, selflessness, and familial bonds) (Duhaylonsod & Cepeda, 2022), the importance of the equality shared between women and men (Naholowa'a, 2018), and ongoing efforts to decolonize paleontology (Monarrez et al., 2021). 

Fona herzogae sp. nov.

  Etymology: The specific epithet honors Lisa Herzog (discoverer of the Mini Troll locality) for her unparalleled dedication to the paleontology program at the NCSM and the collection, care, and conservation of fossil specimens worldwide.

CONCLUSION: 

Fona herzogae adds to the cryptic diversity of the Mussentuchit Member dinosaur fauna, serving as an important component of this exceptional mid-Cretaceous ecosystem. It would have lived alongside the hadrosauromorph Eolambia caroljonesa (McDonald et al., 2017), the Rhabdadontomorph Iani smithi (Zanno, Gates, et al., 2023), the small-bodied tyrannosaur Moros intrepidus (Zanno, Tucker, et al., 2019), the large-bodied allosaurian Siats meekerorum (Zanno & Makovicky, 2013), an unnamed oviraptorosaur (Zanno, Avrahami, et al., 2019) and neoceratopsian (Zanno, Tucker, et al., 2023), and a collection of other terrestrial vertebrates (Avrahami et al., 2018).

The presence of a distinct thescelosaurine taxon in the Mussentuchit member supports the hypothesis that the ancestors of Thescelosaurus were present in North America as early as the Cenomanian, co-inhabiting the continent with their sister-taxon Orodrominae. To date, members of these clades have not been found together, suggesting different habitat preferences. Shared ecomorphology with, and a close phylogenetic affinity with Oryctodromeus demonstrated here, supports a shared semi-fossorial lifestyle. Some of the extensive intraspecific variation among specimens of Fona is likely attributable to ontogenetic transformations, whereas others may suggest a broad phenotypic range for the taxon or may point to sexual dimorphism.

 

Haviv M. Avrahami, Peter J. Makovicky, Ryan T. Tucker, Lindsay E. Zanno. 2024. A New semi-fossorial thescelosaurine Dinosaur from the Cenomanian-age Mussentuchit Member of the Cedar Mountain Formation, Utah. The Anatomical Record

DOI: doi.org/10.1002/ar.25505

https://sciences.ncsu.edu/news/life-underground-suited-new-dinosaur-fine