Irenosaurus

Irenosaurus; Temporal range: Early Cretaceous, Aptian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Subclass:	Diapsida
Infraclass:	Archosauromorpha?
Order:	Choristodera
Genus:	Irenosaurus; Efimov, 1988
Species
	I. egloni (Efimov, 1983 [originally Tchoiria egloni]) (type);

Irenosaurus is a genus of choristodere, a type of amphibious reptile. It is known from a single fragmentary postcranial skeleton (PIN 3386/2), discovered in the Aptian-age Lower Cretaceous Hühteeg Formation at Hüren Dukh, central Mongolia. The type species is I. egloni, which was originally described as a new species of the related choristodere Tchoiria in 1983 by Efimov. Efimov transferred the species to the new genus Irenosaurus in 1988.[1] Evans and Hecht (1993) questioned the separation of the taxon from Tchoiria namsarai from the same locality on the grounds that the differences between the two may not have been greater than those of various species of the choristodere Champsosaurus.[2] A later review by Efimov and Storrs (2000) retained the two as separate, noting that some characteristics of Irenosaurus are more like Khurendukhosaurus, also known from the same site, at the same time recognizing the difficulties of distinguishing three genera from the same locality.[1] Irenosaurus was a small choristodere, approximately 1 to 1.5 metres (3.3 to 4.9 ft) long. It is known from what are interpreted as lake deposits.[1]

References

Efimov, Mikhail B.; Storrs, Glenn W. (2000). "Choristodera from the Lower Cretaceous of northern Asia". In Benton, Michael J.; Shishkin, Mikhail A.; Unwin, David M.; Kurochkin Evgenii N. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 390–401. ISBN 0-521-55476-4.
Evans, S.E.; Hecht, M.K. (1993). "A history of an extinct reptilian clade, the Choristodera: longevity, Lazarus-Taxa, and the fossil record". Evolutionary Biology. 27: 323–338. doi:10.1007/978-1-4615-2878-4_8.

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[MEGS00-1] Efimov, Mikhail B.; Storrs, Glenn W. (2000). "Choristodera from the Lower Cretaceous of northern Asia". In Benton, Michael J.; Shishkin, Mikhail A.; Unwin, David M.; Kurochkin Evgenii N. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 390–401. ISBN 0-521-55476-4.

[SE93-2] Evans, S.E.; Hecht, M.K. (1993). "A history of an extinct reptilian clade, the Choristodera: longevity, Lazarus-Taxa, and the fossil record". Evolutionary Biology. 27: 323–338. doi:10.1007/978-1-4615-2878-4_8.