Coloniatherium

Coloniatherium Temporal range: Late Cretaceous (?Maastrichtian)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Superorder:	Dryolestoidea
Family:	Mesungulatidae
Genus:	Coloniatherium Rougier et al., 2009
Species:	C. cilinskii
Binomial name
Coloniatherium cilinskii Rougier et al., 2009

Coloniatherium is a dryolestoid mammal from the Late Cretaceous of Argentina. The single species, Coloniatherium cilinskii, was a large member of the family Mesungulatidae.

Coloniatherium was named in 2009 by Guillermo Rougier and colleagues and assigned to the family Mesungulatidae within the Dryolestoidea. Dryolestoidea is an extinct mammalian group that occurred in North America, Eurasia, and Africa during the Jurassic and Early Cretaceous, but survived in South America during the Late Cretaceous and into the Paleocene. The generic name, Coloniatherium, combines the name of the La Colonia Formation, the stratigraphical unit where fossils of the animal were found, and its namesake the Sierra de La Colonia with the Greek therion "beast". The specific name, cilinskii, honors Juan Cilinski, a local rancher who helped with the fieldwork that led to the discovery of Coloniatherium.

Coloniatherium is known from a few jaw fragments, a number of isolated teeth, and some petrosals (ear bones). It was a large mesungulatid. The animal had an unknown number of incisors (probably two or three in the lower jaw), one canine, three premolars, and three molars per jaw quadrant. It is larger than Mesungulatum, has broader molars, and the back molars are more reduced; the two also differ in numerous details of tooth morphology. The first molar has three roots, a trait shared only with Leonardus from the approximately contemporaneous Los Alamitos Formation of Argentina among dryolestoids.

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