A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record

2020/11/03 by Ben T. Kligman, Adam D. Marsh, Hans‐Dieter Sues +1 · 3 citations
Earth and Planetary Sciences · Environmental Science · #Paleontology and Evolutionary Biology #Evolution and Paleontology Studies #Amphibian and Reptile Biology

paper · pdf · doi:10.1098/rsbl.2020.0631

openalex publication_date 2020/11/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/27

Abstract

The Upper Triassic tetrapod fossil record of North America features a pronounced discrepancy between the assemblages of present-day Virginia and North Carolina relative to those of the American Southwest. While both are typified by large-bodied archosaurian reptiles like phytosaurs and aetosaurs, the latter notably lacks substantial representation of mammal relatives, including cynodonts. Recently collected non-mammalian eucynodontian jaws from the middle Norian Blue Mesa Member of the Chinle Formation in northeastern Arizona shed light on the Triassic cynodont record from western equatorial Pangaea. Importantly, they reveal new biogeographic connections to eastern equatorial Pangaea as well as southern portions of the supercontinent. This discovery indicates that the faunal dissimilarity previously recognized between the western and eastern portions of equatorial Pangaea is overstated and possibly reflects longstanding sampling biases, rather than a true biogeographic pattern.

Citations

• The earliest bird-line archosaurs and the assembly of the dinosaur body plan
• The origin of squamates revealed by a Middle Triassic lizard from the Italian Alps
• First record of a basal mammaliamorph from the early Late Triassic Ischigualasto Formation of Argentina

Cited by

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• Kataigidodon [wikipedia]