Idiosaura, new reptile from Upper Triassic of Virginia + extinct marine megafauna

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Ben Creisler

Jun 10, 2024, 2:28:14 PM (4 days ago) Jun 10
Ben Creisler

Recent papers:

Idiosaura virginiensis gen. et sp. nov.

Ben T. Kligman, Hans-Dieter Sues & Keegan M. Melstrom (2024)
A new lizard-like reptile with unusual mandibular neurovasculature from the Upper Triassic of Virginia
Journal of Vertebrate Paleontology e2353636

Here, we report a new small-bodied reptile taxon, Idiosaura virginiensis gen. et sp. nov., from the Upper Triassic (Carnian) Vinita Formation of the Richmond basin (Newark Supergroup) in east-central Virginia, U.S.A. The material consists of a fragmentary dentary bearing numerous tall cylindrical teeth implanted in a pleurodont fashion into spongy alveolar tissue. Micro-CT scan data reveal an unusual and complex network of interconnected neurovascular canals within the dentary with connections to the alveolar tissue and pulp cavities of the teeth. The external anatomy of the dentary is consistent with that of Triassic kuehneosaurid reptiles, suggesting affinities to that group; the results of a phylogenetic analysis were inconclusive but do not exclude kuehneosaurid relationships. Alongside the recently described Micromenodon pitti (Rhynchocephalia) and Vinitasaura lizae (Lepidosauromorpha), the new taxon adds to the relatively diverse assemblage of small-bodied reptiles known from the Tomahawk microvertebrate bonebed (USNM locality 39981). Relative tooth complexities of I. virginiensis and V. lizae were analyzed using the Orientation Patch Count Rotated method, and results suggest that the rise of lepidosauromorph ecomorphologies specializing for feeding on invertebrates occurred in Triassic communities alongside non-lepidosauromorph taxa with similar mandibulo-dental features, as in kuehneosaurs.


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Catalina Pimiento, Kristína Kocáková, Gregor H. Mathes, Thodoris Argyriou, Edwin-Alberto Cadena, Jack A. Cooper, Dirley Cortés, Daniel J. Field, Christian Klug, Torsten M. Scheyer, Ana M. Valenzuela-Toro, Timon Buess, Meike Günter, Amanda M. Gardiner, Pascale Hatt, Geraldine Holdener, Giulia Jacober, Sabrina Kobelt, Sheldon Masseraz, Ian Mehli, Sarah Reiff, Eva Rigendinger, Mimo Ruckstuhl, Santana Schneider, Clarissa Seige, Nathalie Senn, Valeria Staccoli, Jessica Baumann, Livio Flüeler, Lino J. Guevara, Esin Ickin, Kimberley C. Kissling, Janis Rogenmoser, Dominik Spitznagel, Jaime A. Villafaña and Chiara Zanatta (2024)
The extinct marine megafauna of the Phanerozoic
Cambridge Prisms: Extinction 2: e7

The modern marine megafauna is known to play important ecological roles and includes many charismatic species that have drawn the attention of both the scientific community and the public. However, the extinct marine megafauna has never been assessed as a whole, nor has it been defined in deep time. Here, we review the literature to define and list the species that constitute the extinct marine megafauna, and to explore biological and ecological patterns throughout the Phanerozoic. We propose a size cut-off of 1 m of length to define the extinct marine megafauna. Based on this definition, we list 706 taxa belonging to eight main groups. We found that the extinct marine megafauna was conspicuous over the Phanerozoic and ubiquitous across all geological eras and periods, with the Mesozoic, especially the Cretaceous, having the greatest number of taxa. Marine reptiles include the largest size recorded (21 m; Shonisaurus sikanniensis) and contain the highest number of extinct marine megafaunal taxa. This contrasts with today’s assemblage, where marine animals achieve sizes of >30 m. The extinct marine megafaunal taxa were found to be well-represented in the Paleobiology Database, but not better sampled than their smaller counterparts. Among the extinct marine megafauna, there appears to be an overall increase in body size through time. Most extinct megafaunal taxa were inferred to be macropredators preferentially living in coastal environments. Across the Phanerozoic, megafaunal species had similar extinction risks as smaller species, in stark contrast to modern oceans where the large species are most affected by human perturbations. Our work represents a first step towards a better understanding of the marine megafauna that lived in the geological past. However, more work is required to expand our list of taxa and their traits so that we can obtain a more complete picture of their ecology and evolution.

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