Dongusuchus

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Dongusuchus
Temporal range: Middle Triassic, Anisian
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Aphanosauria
Genus: Dongusuchus
Sennikov, 1988
Type species
Dongusuchus efremovi
Sennikov, 1988

Dongusuchus (meaning Donguz River crocodile in

capitosaurid Eryosuchus, the most common organism found from the assemblage. The locality dates back to the Anisian and early Ladinian stages of the Middle Triassic.[2]

Sennikov (1988) and Gower and Sennikov (2000) suggested that Dongusuchus was a gracile rausuchian with a long,

archosaurian archosauriform. According to Nesbitt (2009), the poorly-defined crista tibiofibularis and the absence of a distinct anteromedial tuber of the proximal portion of the thighbone in Dongusuchus suggest that it is not a member of Archosauria. Although Gower and Sennikov (2000) suggested that the distinct sigmoidal shape of Dongusuchus femur is unique, a similar shape is present in the femora of some phytosaurs. A paratype tibia was also found to be more closely related to Euparkeria and phytosaurs, on the basis of its convex and rounded distal surface. Additionally, the proximal surface of the tibia lacks a trait present in nearly all pseudosuchians, a depression on its lateral condyle. Nesbitt assigned Dongusuchus to Archosauriformes on the basis of the following traits: its femur has a low fourth trochanter, and the distal condyles do not expand markedly beyond the shaft. These traits suggest that Dongusuchus was an archosauriform more derived than Erythrosuchus.[3]

Dongusuchus was also excluded from Archosauria by Niedźwiedzki et al. (2014)[4] and a new large cladistic analysis of archosauromorphs by Ezcurra (2016)[5] found Dongusuchus to be the sister taxon to the Indian Yarasuchus. Both Dongusuchus and Yarasuchus were recovered in a clade with Spondylosoma and Teleocrater by Nesbitt et al. (2017)[6] at the base of Avemetatarsalia, making them bird-line archosaurs.

References

  1. ^ a b Sennikov, A. G. (1988) Novyye rauizukhidy iz triasa yevropeyskoy chasti SSSR. Paleontol. Zhurn. 1990 (2): 124-128 Moscow.
  2. ^ a b Gower, D. J. and Sennikov, A. G. (2000). Early archosaurs from Russia. In M. J. Benton, E. N. Kurochkin, M. A. Shishkin, D. M. Unwin (eds.), The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press, Cambridge. pp. 140-159
  3. ^ Sterling J. Nesbitt (2009). "The early evolution of archosaurs: Relationships and the origin of major clades". Columbia University (Open Access Dissertation): 1–632.
  4. S2CID 85312134
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  6. ^ Nesbitt SJ et al. 2017. The earliest bird-line archosaurs and the assembly of the dinosaur body plan. Nature.