Tsylmosuchus

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Tsylmosuchus
Temporal range: Early Triassic Induan–Olenekian
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Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Family: †Proterosuchidae
Subfamily: †
Chasmatosuchinae
Genus: †Tsylmosuchus
Sennikov, 1990
Species
  • T. jakovlevi Sennikov, 1990 (type)
  • T. samarensis Sennikov, 1990
  • T. donensis Sennikov, 1990
Synonyms[1]

Tsylmosuchus is an extinct

archosauriform reptile known from Western Russia. Fossils referred to Tsylmosuchus occurred over a wide area in sediments corresponding to the Induan and Olenekian stages of the Early Triassic. Most of these fossils are fragmentary neck vertebrae which were originally reported as sharing similarities with crocodile-line archosaurs (pseudosuchians) such as Mandasuchus. As a result, Tsylmosuchus was first described as part of the family Rauisuchidae, making it supposedly one of the oldest known archosaurs.[2][3][4] However, its fragmentary remains do not show any of the distinguishing features of rauisuchids or even pseudosuchians in general, so Tsylmosuchus has more recently been interpreted as an indeterminate archosauriform. Although three species of Tsylmosuchus have been named, they lack diagnostic traits and are probably not distinct from each other.[5] In 2023, Tsylmosuchus was reinterpreted as a proterosuchid, specifically a member of the subfamily Chasmatosuchinae.[6]

Discovery

The genus is named after the

Lipovskaya Formation of the Yarenskain Gorizont
(Upper Olenekian).

Tsylmosuchus samariensis, described from a single site in Borskoi (Samara Oblast, along the Obshchy Syrt) dating to the Rybinskian Gorizont (Induan), was synonymized with Chasmatosuchus rossicus by Ezcurra (2016), who also made the Tsylmosuchus type species a nomen dubium.[7] However, in 2023, Ezcurra reversed this decision and placed all three species in Tsylmosuchus again, and found the genus to be a proterosuchid.[6]

Description

Tsylmosuchus is known primarily from vertebrae. These vertebrae have been compared to "rauisuchid" vertebrae, from the Manda Beds of Tanzania, which are now referred to Mandasuchus. Like several contemporary "rauisuchians" (Energosuchus and Vytshegdosuchus), Tsylmosuchus has elongated cervical vertebrae. This would have given it a relatively long neck.[3]

Nesbitt (2009) suggested that elongated

archosauriforms.[5]

Sennikov (2022) interpreted Tsylmosuchus as a member of the Ctenosauriscidae and also suggested that Scythosuchus may have been the same animal as Tsylmosuchus.[1] In contrast, it was recovered as a member of the Proterosuchidae by Ezcurra (2023), who reversed some of his previous reclassifications of the genus.[6]

Paleobiology

Along with small proterosuchids such as

archosauriforms. They correspond to a massive river basin, which likely experienced a trend of increasing humidity during the later part of the Olenekian.[3]

References

  1. ^
    S2CID 248132677
    .
  2. ^ a b c Sennikov, A.G. (1990). "New data on the rauisuchids of Eastern Europe". Paleontological Journal. 1990 (3): 3–16.
  3. ^ a b c d e Gower, D.J.; Sennikov, A.G. (2003). "Early archosaurs from Russia". In Benton, M.J.; Shishkin, M.A.; Unwin, D.M. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 140–159.
  4. ^ Borsuk−Białynicka, M.; Sennikov, A.G. (2009). "Archosauriform postcranial remains from the Early Triassic karst deposits of southern Poland" (PDF). Palaeontologica Polonica. 65: 283–328.
  5. ^ a b Sterling J. Nesbitt (2009). "The early evolution of archosaurs: Relationships and the origin of major clades". Columbia University (Open Access Dissertation): 1–632.
  6. ^
    PMID 37885992
    .
  7. ^ Ezcurra, M.D., 2016. The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms. PeerJ 4:e1778;DOI10.7717/peerj.1778

External links

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