Jaikosuchus

Jaikosuchus Temporal range: 251.3 –247.2 Ma[1] PreꞒ Ꞓ O S D C P T J K Pg N ↓ Early Triassic (Olenekian)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauromorpha
Clade:	Archosauriformes
Family:	†Proterosuchidae
Subfamily:	†Chasmatosuchinae
Genus:	†Jaikosuchus Sennikov, 1990
Species:	†J. magnus
Binomial name
†Jaikosuchus magnus (Ochev, 1979)
Synonyms
Chasmatosuchus magnus Ochev, 1979

Jaikosuchus is an extinct genus of proterosuchid archosauriform. It contains a single species, J. magnus. Fossils have been found from European Russia that date back to the upper Olenekian stage of the Early Triassic.^[2]

The genus was originally assigned as a new species of the proterosuchid Chasmatosuchus in 1979, but was later put in its own genus in 1990. It has often been described as an erythrosuchid, a rauisuchian or a basal suchian closely related to rauisuchians rather than the more traditional view of it being a more primitive archosaur.^[3][4] In 2016, it was synonymized again with Chasmatosuchus by Ezcurra et al., but was revived as a distinct genus by Ezcurra et al. again in a 2023 overview of proterosuchid taxonomy, who found its vertebral morphology to be distinct from that of Chasmatosuchus. Both were placed in the new subfamily Chasmatosuchinae.^[5][6]

References

1. "†Chasmatosuchus magnus Ochev 1979 (archosauromorph)". Fossilworks.
2. Shishkin, M. A., Ochev, V. G., Lozovskii, V. R. and Novikov, I. V. (2000). Tetrapod biostratigraphy of the Triassic of Eastern Europe. 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. http://www.helsinki.fi/~mhaaramo/metazoa/deuterostoma/chordata/archosauria/pseudosuchia/suchia_2.html
4. Borsuk-Bialynicka, M., Cook, E., Evans, S. E. and Maryafiska, T. (1999). A microvertebrate assemblage from the Early Triassic of Poland. Acta Palaeontologica Polonica 44(2):167-188.
5. Ezcurra, Martín D. (2016-04-28). "The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms". PeerJ. 4: e1778. doi:10.7717/peerj.1778. ISSN 2167-8359. PMC 4860341.
6. Ezcurra, Martín D.; Bandyopadhyay, Saswati; Sengupta, Dhurjati P.; Sen, Kasturi; Sennikov, Andrey G.; Sookias, Roland B.; Nesbitt, Sterling J.; Butler, Richard J. (25 October 2023). "A new archosauriform species from the Panchet Formation of India and the diversification of Proterosuchidae after the end-Permian mass extinction". Royal Society Open Science. 10 (10). doi:10.1098/rsos.230387. ISSN 2054-5703. PMC 10598453. PMID 37885992.