Article
Anatomy & Morphology
Thomas Cowgill, Mark T. Young, Julia A. Schwab, Stig Walsh, Lawrence M. Witmer, Yanina Herrera, Kathleen N. Dollman, Jonah N. Choiniere, Stephen L. Brusatte
Summary: Thalattosuchians were a mainly marine group of crocodylomorphs in the Mesozoic era, with recent research revealing new details about the evolutionary transition from terrestrial to marine to pelagic forms. The study found that thalattosuchians have greatly reduced paranasal sinus systems, primarily consisting of the antorbital sinus. This characteristic may have appeared early in the marine transition of thalattosuchians.
ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY
(2022)
Article
Anatomy & Morphology
N. Adam Smith, Krista L. Koeller, Julia A. Clarke, Daniel T. Ksepka, Jonathan S. Mitchell, Ali Nabavizadeh, Ryan C. Ridgley, Lawrence M. Witmer
Summary: In the study of wing-propelled diving birds, dippers are unique in their adaptation to underwater locomotion, showing differences in anatomical characteristics compared to other taxa. While sharing some similarities with nonpasserine wing-propelled divers, dippers exhibit distinct muscular and integumentary novelties which may precede skeletal and neuroendocranial morphology in the acquisition of this novel locomotory mode.
ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY
(2022)
Article
Anatomy & Morphology
William G. Parker, Sterling J. Nesbitt, Randall B. Irmis, Jeffrey W. Martz, Adam D. Marsh, Matthew A. Brown, Michelle R. Stocker, Sarah Werning
Summary: A study describes the early-diverging pseudosuchian Revueltosaurus callenderi from Arizona, based on 12 skeletons found in a bonebed, which possess unique features that help clarify its relationships within Pseudosuchia. Histological analysis of the femur indicates that the individuals were not young juveniles and had slow growth rate.
ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY
(2022)
Article
Paleontology
Sterling J. Nesbitt, Michelle R. Stocker, Martin D. Ezcurra, Nicholas C. Fraser, Andrew B. Heckert, William G. Parker, Bill Mueller, Saradee Sengupta, Saswati Bandyopadhyay, Adam C. Pritchard, Adam D. Marsh
Summary: Archosauromorph reptiles underwent rapid diversification, with increases in morphological and body size disparity, and expanded into new adaptive landscapes. Malersaurus is identified as an early diverging, but late-surviving, carnivorous member of Azendohsauridae within Allokotosauria. Fossils from western North America suggest that Allokotosauria had a near-global distribution from the Middle Triassic to Late Triassic.
PAPERS IN PALAEONTOLOGY
(2022)
Meeting Abstract
Biochemistry & Molecular Biology
Khanh To, Todd Green, Lawrence Witmer, Michelle Stocker
Article
Anatomy & Morphology
Casey M. Holliday, Kaleb C. Sellers, Emily J. Lessner, Kevin M. Middleton, Corrine Cranor, Conner D. Verhulst, Stephan Lautenschlager, Kenneth Bader, Matthew A. Brown, Matthew W. Colbert
Summary: New imaging and biomechanical approaches have led to a renaissance in our understanding of crocodylian anatomy, particularly in the study of jaw muscles. These approaches, such as iodine-contrast microCT and 3D modeling, provide new insights into the anatomy, diversity, and function of jaw muscles and the heads of crocodylians.
ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY
(2022)
Article
Anatomy & Morphology
Rebecca K. Hawkins, Christopher J. Bell, Jennifer C. Olori, Michelle R. Stocker
Summary: A snake-like body plan and burrowing lifestyle are characteristic of many vertebrate groups due to convergent evolution. One such group is amphisbaenians, limbless fossorial lizards that exhibit head-first burrowing behavior. Their skulls are more rigid and coossified compared to nonburrowing lizards. In this study, intraspecific variation in the cranial osteology of amphisbaenians was investigated using seven individuals of Diplometopon zarudnyi. The study revealed qualitative and quantitative differences in skull and individual skull element morphology, which may be the result of different ontogenetic stages or biomechanical optimization for head-first burrowing.
JOURNAL OF MORPHOLOGY
(2022)
Article
Multidisciplinary Sciences
Ben T. T. Kligman, Bryan M. M. Gee, Adam D. D. Marsh, Sterling J. J. Nesbitt, Matthew E. E. Smith, William G. G. Parker, Michelle R. R. Stocker
Summary: Scientists have discovered the oldest caecilian fossil in Arizona, USA, suggesting that the origin of caecilians can be traced back to the Triassic period. These fossils reveal the tempo and mode of early caecilian morphological and functional evolution, providing new evidence supporting a single origin of caecilians with other amphibians.
Article
Anatomy & Morphology
Adam C. C. Pritchard, Randall B. B. Irmis, Jennifer C. C. Olori, Sterling J. J. Nesbitt, Nathan D. D. Smith, Michelle R. R. Stocker, Alan H. H. Turner
Summary: The femoral morphology of Triassic drepanosauromorphs is unique, allowing for greater femoral adduction and protraction compared to other Permian-Triassic diapsids. This study provides valuable insights into the evolution of reptile femora and their locomotor capabilities.
ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY
(2023)
Article
Anatomy & Morphology
Chris Tijani Barker, Darren Naish, Jacob Trend, Lysanne Veerle Michels, Lawrence Witmer, Ryan Ridgley, Katy Rankin, Claire E. Clarkin, Philipp Schneider, Neil J. Gostling
Summary: The digital reconstruction of neurocranial endocasts provides insight into the brain structure and ecological attributes of fossil taxa. This study focuses on the braincase endocasts of Baryonyx walkeri and Ceratosuchops inferodios from the Lower Cretaceous of England. The findings suggest that baryonychines had similar neurosensory capabilities to other non-maniraptoriform theropods and did not require substantial modifications in brain and sensory systems during the transition to semi-aquatic generalists.
JOURNAL OF ANATOMY
(2023)
Article
Multidisciplinary Sciences
Mark T. Young, Charlotte I. W. Bowman, Arthur Erb, Julia A. Schwab, Lawrence M. Witmer, Yanina Herrera, Stephen L. Brusatte
Summary: Thalattosuchian crocodylomorphs were a diverse group that lived in water from the Early Jurassic to the Early Cretaceous. The subclade Metriorhynchoidea went through a remarkable evolution from semi-aquatic ambush predators to fully aquatic forms living in open oceans. Thalattosuchians share a unique palatal morphology with fossil cetaceans, having paired grooves along the palatal surface. By investigating CT scans of thalattosuchian and extant crocodylian species, this study reveals that all thalattosuchians had osseous canals connected to the oral cavity, which transmitted hypertrophied nasal vessels for heat exchange. This suggests that thalattosuchians had a complex thermoregulatory system to maintain stable temperatures for their neurosensory tissues.
Article
Multidisciplinary Sciences
Rodrigo T. Muller, Martin D. Ezcurra, Mauricio S. Garcia, Federico L. Agnolin, Michelle R. Stocker, Fernando E. Novas, Marina B. Soares, Alexander W. A. Kellner, Sterling J. Nesbitt
Summary: Studying the well-preserved partial skeleton of Venetoraptor gassenae provides a more comprehensive understanding of the skull and ecology of dinosaur and pterosaur precursors. The discovery of a sharp raptorial-like beak and long trenchant claws suggests the loss of quadrupedalism in these precursors. The morphological diversity of these precursors exceeds that of Triassic dinosaurs and resembles that of Triassic pterosaurs.
Article
Paleontology
Davide Foffa, Sterling J. J. Nesbitt, Ben T. T. Kligman, Richard J. J. Butler, Michelle R. R. Stocker
Summary: Anisodontosaurus greeri is a small-bodied tetrapod with a heterodont dentition from the Middle Triassic. Its evolutionary relationships have been uncertain, but new data from micro-computed tomography scans suggest that it belongs to the archosauromorph clade Trilophosauridae. Comparison with other trilophosaurids reveals similarities with Variodens inopinatus, and cladistic analyses confirm the existence of two distinct lineages within Trilophosauridae. These findings have important implications for our understanding of the early evolution and distribution of trilophosaurids.
JOURNAL OF VERTEBRATE PALEONTOLOGY
(2023)
Article
Paleontology
Adam D. Marsh, William G. Parker, Sterling J. Nesbitt, Ben T. Kligman, Michelle R. Stocker
Summary: Non-archosaur archosauromorphs, including a newly discovered malerisaurine azendohsaurid named Puercosuchus traverorum, were important members of the global Middle and Late Triassic continental ecosystems. This finding is significant for understanding the diversity of azendohsaurids during the middle and late Triassic periods.
JOURNAL OF PALEONTOLOGY
(2022)