Anhanguerid pterosaur specimen from Brazil + archosauromorphs from Late Triassic of Brazil + Diictodon (Permian dicynodont) cranial growth series + squamate dental development

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

Some recent reptile and tetrapod papers:

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João Lucas da Silva,Tabata Bentes,Rodrigo V. Pêgas,Alexander W. A. Kellner &Fabiana Rodrigues Costa (2024)
A new anhanguerid pterosaur specimen from the Romualdo Formation, Araripe Basin (Lower Cretaceous, Northeastern Brazil)
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2024.2372650
https://www.tandfonline.com/doi/full/10.1080/08912963.2024.2372650


Pterosaurs, flying reptiles that lived during the Mesozoic era, were the first vertebrates to develop powered flight. Despite being patchy, the pterosaur fossil record extends worldwide, being quite diverse at the Araripe Basin, Brazil. The Romualdo Formation (Aptian-Albian), a Konservat Lagerstätten rich in calcareous concretions, has yielded several of these exceptionally well-preserved, three-dimensional fossils. MN 4727-V, the focus of the present study, consists exclusively of three-dimensionally preserved post-cranial axial and appendicular elements. The anatomy suggests that MN 4727-V is a pteranodontoid since it exhibits an enlarged, warped deltopectoral crest and a subtriangular distal articulation of the humerus. The phylogenetic analysis recovered MN 4727-V as an anhanguerid by the combination of the following characters: scapula substantially shorter than the coracoid (sca/co < 0.80), and posterior expansion of the sternal articulation of the coracoid. The presence of elliptical-shaped, dorsomedially inclined depressions on the dorsal surface of the prezygapophyses of the preserved cervicals has never been reported for any other anhanguerid, although they might not be diagnostic to MN 4727-V. The tail bears unique middle caudals that exhibit ventral projections, a character previously reported only for Anhanguera piscator. The wingspan of MN 4727-V, a juvenile individual, was estimated to be about 3.9 metres.

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Mariana Doering, Martín D. Ezcurra, Jeung Hee Schiefelbein, Maurício Silva Garcia & Rodrigo Temp Müller (2024)
New archosauromorph remains provide data on the age of a unique Late Triassic assemblage from southern Brazil
Journal of South American Earth Sciences 105046
doi: https://doi.org/10.1016/j.jsames.2024.105046
https://www.sciencedirect.com/science/article/abs/pii/S0895981124002682

Highlights

New archosauromorph specimens from the Niemeyer complex are described.
The materials include remains of rhynchosaurs, dinosaurs, and silesaurids.
The rhynchosaur remains belong to Teyumbaita sulcognathus.
This is the first record of Teyumbaita sulcognathus for the Niemeyer complex.
This occurrence suggests that the site dates close to the Carnian-Norian boundary.


Abstract

The Santa Maria Supersequence, an important stratigraphic unit in the Paraná Basin, yielded a diverse range of Triassic tetrapod assemblages, providing valuable insights into the evolutionary history of southwestern Pangea. This study focuses on the Candelária Sequence of the Santa Maria Supersequence, which includes the Hyperodapedon Assemblage Zone (AZ) and the Riograndia AZ. The Hyperodapedon AZ is characterized by the presence of Hyperodapedon rhynchosaurs alongside a diverse array of other taxa, including dinosaurs, pseudosuchians, and cynodonts. In contrast, the Riograndia AZ preserves mostly small cynodonts, lepidosauromorphs, and sauropodomorph dinosaurs. Whereas biostratigraphic correlations between several localities of the Candelária Sequence have been firmly established, certain sites, like the Niemeyer complex in the Agudo municipality of southern Brazil, present challenges because of their unusual assemblage composition, which result in ambiguous depositional ages. Despite yielding thousands of fossil specimens, the Niemeyer complex lacks index fossils typical of the known Brazilian AZs, making reliable correlation with other sites challenging. This study presents and describes new archosauromorph specimens discovered at the upper portion of the Niemeyer complex. The new materials include a rhynchosaur, a saurischian dinosaur, and a possible silesaurid, which represent the first record of these groups for the site. A phylogenetic analysis of the rhynchosaur material provides insights into its taxonomic affinities, offering valuable data for biostratigraphic comparisons. The new data reinforces an age (early Norian?) that is younger than that of the typical outcrops assigned to the Hyperodapedon AZ. Furthermore, these new specimens contribute to the unique assemblage of the Niemeyer complex, shedding light on its significance within the context of the Santa Maria Supersequence and the broader landscape of southern Brazil during the Triassic Period.

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Free pdf:

Caitlin Rabe, Jesús Marugán-Lobón, Roger M. H. Smith and Anusuya Chinsamy (2024)
Geometric morphometric analysis of an ontogenetic cranial series of the Permian dicynodont Diictodon feliceps
Proceedings of the Royal Society B: Biological Sciences 291(2027): 20240626
doi: https://doi.org/10.1098/rspb.2024.0626
https://royalsocietypublishing.org/doi/10.1098/rspb.2024.0626

Free pdf:
https://royalsocietypublishing.org/doi/epdf/10.1098/rspb.2024.0626

The Karoo Basin of South Africa is renowned for its abundance and diversity of therapsid fossils. Among the most ubiquitous and persistent of the Permian fauna is the small herbivorous dicynodont Diictodon feliceps. Intraspecific variation in Diictodon is historically confounding, and while ontogeny is frequently cited as a potential source of variation, observable developmental changes have never been calibrated. The present study revisits this issue, comparing three-dimensional landmark configurations of 82 Diictodon crania to investigate the association between shape, size and dimorphism. Beyond the statistically significant relationship between shape and allometry, our results determine the shape differences between juvenile and adult skulls of Diictodon, aligned with common craniofacial features documented in other tetrapod taxa. Functionally, these changes are attributed to development of the jaw musculature for feeding on larger, tougher plant matter during later ontogeny. Cranial morphological variation owing to sexual dimorphism is negligible, but distinct differences are noted in the allometric trajectories of each morphotype. A component of non-allometric variation cannot be accounted for, and we propose that this represents natural variation, rather than an artefact of taphonomic deformation.

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Free pdf:

Daria Razmadze, Lotta Salomies & Nicolas Di-Poï (2024)
Squamates as a model to understand key dental features of vertebrates
Developmental Biology (advance online publication)
doi: https://doi.org/10.1016/j.ydbio.2024.07.011
https://www.sciencedirect.com/science/article/pii/S001216062400191X


Highlights

Teeth are a hallmark features of vertebrates
Large ecomorphological diversity of squamate dentitions remains largely unexplored
Central bearded dragon is an emerging model for evo-devo and dental research
Squamate dentition: diversity, development, and replacement importance
Squamate models offer crucial insights into vertebrate tooth evolution


Abstract

Thanks to their exceptional diversity, teeth are among the most distinctive features of vertebrates. Parameters such as tooth size, shape, number, identity, and implantation can have substantial implications for the ecology and certain social behaviors of toothed species. Despite decades of research primarily focused on mammalian dentition, particularly using the laboratory mouse model, squamate reptiles (“lizards” and snakes) offer a wide array of tooth types and dentition variations. This diversity, which includes differences in size, shape, function, and replacement capacity, provides invaluable opportunities for investigating these fundamental properties. The central bearded dragon (Pogona vitticeps), a popular pet species with well-established husbandry practices, is of particular interest. It features a broad spectrum of morphs and spontaneous mutants and exhibits a wide range of heterodont phenotypes, including variation in the size, shape, number, implantation, and renewal of teeth at both posterior and anterior positions. These characteristics position the species as a crucial model organism for developmental studies in tooth research and for gaining deeper insights into evolutionary patterns of vertebrate dentitions. In this article, we provide an overview of the current understanding of squamate dentition, its diversity, development, and replacement. Furthermore, we discuss the significant advantages offered by squamate species as model organisms for investigating the evolutionary and developmental aspects of vertebrate dentition.