{{Short description|Extinct genus of mammals}} {{Automatic taxobox | fossil_range = Late Campanian-Latest Thanetian<br />~{{fossilrange|75|56}} | image = Cimolestes stirtoni LACM.jpg | image_caption = Lower jaw (LACM 152546) of ''C. stirtoni'', Natural History Museum of Los Angeles County | taxon = Cimolestes | authority = Marsh, 1889 | type_species = {{extinct}}'''''Cimolestes incisus''''' | type_species_authority = Marsh, 1889 | subdivision_ranks = | subdivision = | synonyms = ''Nyssodon'' {{small|Simpson, 1927}} }}
'''''Cimolestes''''' (from Ancient Greek {{lang|grc-x-classic|Κιμο λέστες}}, 'chalk robber')<ref>{{cite web |url=https://www.biodiversitylibrary.org/page/27791936 |title=Cimolestes |page=189 }} in {{cite journal |last1=Palmer |first1=T. S. |title=Index Generum Mammalium: A List of the Genera and Families of Mammals |journal=North American Fauna |date=23 January 1904 |volume=23 |pages=1–984 |doi=10.3996/nafa.23.0001 |url=https://digital.library.unt.edu/ark:/67531/metadc700949/ |doi-access=free |url-access=subscription }}</ref> is a genus of early eutherians with a full complement of teeth adapted for eating insects and other small animals. Paleontologists have disagreed on its relationship to other mammals, in part because quite different animals were assigned to the genus, making ''Cimolestes'' a grade taxon of animals with similar features rather than a genus of closely related ones. Fossils have been found in North America, South America, Europe and Africa. ''Cimolestes'' first appeared during the Late Cretaceous of North America. According to some paleontologists, ''Cimolestes'' died out at the start of the Paleocene,<ref name="McK&B">{{cite book |author1=McKenna, M. C. |author2=S. K. Bell | year = 1997 | title = Classification of Mammals Above the Species Level | publisher = Columbia University Press | isbn = 978-0-231-11012-9}}</ref> while others report the genus from the early Eocene.<ref name=":0">{{Cite book|last=Grande|first=Lance|title=The Lost World of Fossil Lake; Snapshots from Deep Time|publisher=University of Chicago Press|year=2013|isbn=978-0-226-92296-6|location=Chicago|pages=260–263}}</ref>
Most species have been described from teeth and isolated fragments. One complete articulated skeleton provisionally assigned to ''Cimolestes'' has been found. It shows a small, agile, tree-dwelling predator with long toes for grasping branches and a prehensile tail at least twice the length of its body. It has the largest number of tail vertebrae known in any mammal.<ref name=":0" />
== Classification == The genus was once considered to be that of a marsupial; later, it was reclassified with the placental mammals, as ancestors of the Carnivora and the extinct Creodonta. Recent researchers have agreed the species assigned to ''Cimolestes'' are primitive eutherian mammals, members of a cimolestid clade (an order or family named after the genus), part of the larger clade Didelphodonta (a superorder or order, not to be confused with the marsupial clade Didelphimorphia). Didelphodonts have been placed within the Ferae, as a sister group to Carnivora. However, consensus is emerging that modern placental mammals evolved later than previously thought,<ref>{{cite journal |last1=O'Leary |first1=Maureen A. |last2=Bloch |first2=Jonathan I. |last3=Flynn |first3=John J. |last4=Gaudin |first4=Timothy J. |last5=Giallombardo |first5=Andres |last6=Giannini |first6=Norberto P. |last7=Goldberg |first7=Suzann L. |last8=Kraatz |first8=Brian P. |last9=Luo |first9=Zhe-Xi |last10=Meng |first10=Jin |last11=Ni |first11=Xijun |last12=Novacek |first12=Michael J. |last13=Perini |first13=Fernando A. |last14=Randall |first14=Zachary S. |last15=Rougier |first15=Guillermo W. |last16=Sargis |first16=Eric J. |last17=Silcox |first17=Mary T. |last18=Simmons |first18=Nancy B. |last19=Spaulding |first19=Michelle |last20=Velazco |first20=Paúl M. |last21=Weksler |first21=Marcelo |last22=Wible |first22=John R. |last23=Cirranello |first23=Andrea L. |title=The Placental Mammal Ancestor and the Post—K-Pg Radiation of Placentals |journal=Science |date=2013 |volume=339 |issue=6120 |pages=662–667 |doi=10.1126/science.1229237 |jstor=23365914 |pmid=23393258 |bibcode=2013Sci...339..662O |hdl=11336/7302 |s2cid=206544776 |oclc=827160921 |hdl-access=free }}</ref><ref>{{cite journal |last1=O'Leary |first1=Maureen A. |title=On the Trail of the First Placental Mammals |journal=American Scientist |date=2014 |volume=102 |issue=3 |pages=190–197 |id={{Gale|A370031758}} {{ProQuest|1522775462}} |jstor=43707184 }}</ref> that other types of mammals had long, diversified, and successful histories, and that ''Cimolestes'' and many related genera are stem eutherians, more closely related to placentals than to marsupials but outside of placental mammals proper, and not closely related to any living animal.<ref name="rook">{{Cite journal | last1 = Rook | first1 = D.L. | last2 = Hunter | first2 = J.P. | title = Rooting Around the Eutherian Family Tree: the Origin and Relations of the Taeniodonta | year = 2013 | journal = Journal of Mammalian Evolution | volume = 21 | pages = 1–17 | doi = 10.1007/s10914-013-9230-9| s2cid = 17074668 }}</ref>
''Cimolestes'' in particular follows as the direct outgroup to Taeniodonta, indicating that the latter evolved from forms similar to it.<ref name="rook" />
== Reassigned species == In order to make the genus reflect an actual group of most closely related species, three nominal species of ''Cimolestes'', ''C. magnus'', ''C. cerberoides'', and ''C. propalaeoryctes'', have been reassigned to their own genera, ''Altacreodus'', ''Ambilestes'', and ''Scollardius'', respectively. ''Cimolestes incisus'' (Marsh) and ''Cimolestes stirtoni'' (Clemens) remain within the genus.<ref>{{cite journal |last1=Fox |first1=Richard C. |title=A revision of the Late Cretaceous–Paleocene eutherian mammal Cimolestes Marsh, 1889 |journal=Canadian Journal of Earth Sciences |date=December 2015 |volume=52 |issue=12 |pages=1137–1149 |doi=10.1139/cjes-2015-0113 |bibcode=2015CaJES..52.1137F }}</ref>
== Fossil distribution == Fossils of ''Cimolestes'' have been found in:<ref>[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=40235 ''Cimolestes''] at Fossilworks.org</ref>
;Cretaceous * Canada ** Foremost, Oldman and St. Mary River Formations, Alberta ** Ravenscrag and Frenchman Formations, Saskatchewan * United States ** Hell Creek and Judith River Formations, Montana ** Kirtland Formation, New Mexico ** Lance Formation, Wyoming
;Paleocene * Hainin Formation, Belgium * Santa Lucía Formation (Tiupampan), Bolivia * Ravenscrag and Frenchman Formations, Saskatchewan, Canada * Jbel Guersif Formation, Morocco * United States (Puercan) ** Bear and Hell Creek Formations, Montana ** Ferris Formation, Wyoming
;Eocene * Fossil Butte Member, Green River Formation, Wyoming, United States<ref name=":0" />
==In popular culture== ''Cimolestes'' is featured as an edible creature in the game ''Tasty Planet: Back for Seconds.''
== References == {{Reflist}}
{{Eutheria|C.}} {{Taxonbar|from=Q2273848}}
Category:Fossils of Canada Category:Cimolestans Category:Prehistoric mammal genera Category:Cretaceous–Paleogene boundary Category:Cretaceous mammals of North America Category:Cretaceous Canada Category:Cretaceous United States Category:Hell Creek fauna Category:Paleocene mammals of Africa Category:Fossils of Morocco Category:Paleocene mammals of Europe Category:Paleogene Belgium Category:Fossils of Belgium Category:Paleocene mammals of North America Category:Paleogene Canada Category:Paleogene United States Category:Eocene mammals of North America Category:Campanian genus first appearances Category:Paleocene mammals of South America Category:Paleogene Bolivia Category:Tiupampan Category:Fossils of Bolivia Category:Fossil taxa described in 1889 Category:Taxa named by Othniel Charles Marsh