''Cimolomys'' (Greek for "chalk mouse") is a

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

from the Upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. It was a member of the extinct order

Multituberculata Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct Order (biology), order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the M ...

within the suborder

Cimolodonta Cimolodonta is a clade of Multituberculata, multituberculate mammals that lived from the Cretaceous to the Eocene. They probably lived something of a rodent-like existence until their ecological niche was assumed by true rodents. The more basal ...

and family

Cimolomyidae Cimolomyidae is a family of fossil mammala within the extinct order Multituberculata. Representatives are known from the Late Cretaceous of North America and Mongolia, from the late Santonian to their extinction at the end of the Maastrichtian. ...

. The genus ''Cimolomys'' was named by

Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...

in 1889.

Distribution

Remains of ''Cimolomys'' are widespread throughout the interior west of North America (the former landmass of

Laramidia Laramidia was an island continent that existed during the Late Cretaceous period (99.6–66 Year#SI prefix multipliers, Ma), when the Western Interior Seaway split the continent of North America in two. In the Mesozoic era, Laramidia was an island ...

) throughout the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

, from the late

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

to the end of the

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

. However, a few rare remains from concurrent formations in eastern North America (indeterminate remains from the

Bladen Formation The Bladen Formation is a geologic Formation (geology), formation from the Late Cretaceous (middle Campanian) of North Carolina and South Carolina, USA. It is known for a plethora of terrestrial and aquatic vertebrate fossils, including dinosaurs ...

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

and

Marshalltown Formation The Marshalltown Formation is a Late Cretaceous (Campanian)-aged geologic Formation (geology), formation in New Jersey and Delaware, US. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the format ...

New Jersey New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...

, the latter tentatively assigned to the western species ''C. clarki'') suggest they were also found on the other side of the

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea (geology), inland sea that existed roughly over the present-day Great Plains of ...

, on the landmass of

Appalachia Appalachia ( ) is a geographic region located in the Appalachian Mountains#Regions, central and southern sections of the Appalachian Mountains in the east of North America. In the north, its boundaries stretch from the western Catskill Mountai ...

Species

The species ''Cimolomys clarki'' was named by Sahni in 1972.

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

remains were found in Campanian-Maastrichtian (Upper Cretaceous)

strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

and

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

(United States). Possible remains have also come from

(USA). It probably weighed about 300 g, the same as a malnourished

rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...

. The species ''Cimolomys gracilis'' was named by Marsh O.C. in 1889, and has also been known as ''Cimolomys digona'' (Marsh 1889); ''Meniscoessus brevis''; ''Ptilodus gracilus'' (Osborn H.F. 1893); and ''Selenacodon brevis'' (Marsh 1889). Remains were found in Maastrichtian (Upper Cretaceous) strata of

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux ...

and Wyoming (USA) and

Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

, Canada. This species likely weighed around 415 g, as much as a modern rat. The species ''Cimolomys milliensis'' was named by Eaton J.G. in 1993.. Remains were found in Campanian (Upper Cretaceous) strata of Mill Creek,

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

(USA).

The species ''Cimolomys trochuus'' was named by Lillegraven J.A. in 1969. Remains were found in Maastrichtian (Upper Cretaceous) strata of North America. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

is in the collection of the

University of Alberta The University of Alberta (also known as U of A or UAlberta, ) is a public research university located in Edmonton, Alberta, Canada. It was founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta, and Henry Marshall Tory, t ...

References

* Marsh (1889), "Discovery of Cretaceous Mammalia". ''Am. J. Sci'' 3, 18 & 38: p. 177-180 * Kielan-Jaworowska Z & Hurum JH (2001), "Phylogeny and Systematics of multituberculate mammals". ''Paleontology'' 44, p. 389-429 * Much of this information has been derived fro

MESOZOIC MAMMALS; "basal"

, Boffius, Boffiidae and

Kogaionidae Kogaionidae is a family of fossil mammals within the Extinction, extinct order Multituberculata. Representatives are known from the Upper Cretaceous and the Paleocene of Europe. Having started as island endemics on Hațeg Island during the Upper ...

, an Internet directory {{Taxonbar, from=Q5120158 Cimolodonta Cretaceous mammals of North America Hell Creek fauna Prehistoric mammal genera Santonian genus first appearances Campanian genera Maastrichtian genus extinctions Fossil taxa described in 1889