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Temporal range: Late Cretaceous, 68–66 Ma
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cimolesta
Family: Cimolestidae
Marsh, 1889
Genus: Cimolestes
Marsh, 1889
Type species
Cimolestes incisus
Marsh, 1889

Nyssodon Simpson, 1927

Cimolestes ("Bug Thief") is a genus of basal, non-placental eutherians. Fossils have been found in North America, where they first appeared during the Late Cretaceous; they died out at the start of the Paleocene.[1]

They were once considered to be marsupials, then primitive placental mammals, but now are considered to be members of the order Cimolesta (which was named after the genus), outside of placental mammals proper.[2] Before they were determined to be non-placental eutherians, the cimolestids were once considered the common ancestral group of the clades Carnivora and the extinct Creodonta.

Cimolestes in particular follows as the direct outgroup to Taeniodonta, indicating that the latter evolved from forms similar to it.[2]

Misassigned species[edit]

Three nominal species of Cimolestes, C. magnus, C. cerberoides, and C. propalaeoryctes, have been reassigned to their own genera, Altacreodus, Ambilestes, and Scollardius, respectively.[3]


  1. ^ McKenna, M. C; S. K. Bell (1997). Classification of Mammals Above the Species Level. Columbia University Press. ISBN 0-231-11012-X. 
  2. ^ a b Rook, D.L.; Hunter, J.P. (2013). "Rooting Around the Eutherian Family Tree: the Origin and Relations of the Taeniodonta". Journal of Mammalian Evolution: 1–17. doi:10.1007/s10914-013-9230-9. Retrieved May 2013.  Check date values in: |access-date= (help)
  3. ^ Richard C. Fox (2015) A revision of the Late Cretaceous–Paleocene eutherian mammal Cimolestes Marsh, 1889. Canadian Journal of Earth Sciences (advance online publication) doi: 10.1139/cjes-2015-0113