Cimolomys

Distribution

Remains of Cimolomys are widespread throughout the interior west of North America (the former landmass of Laramidia) throughout the Late Cretaceous, from the late Santonian to the end of the Maastrichtian. However, a few rare remains from concurrent formations in eastern North America (indeterminate remains from the Bladen Formation of North Carolina and Marshalltown Formation of New Jersey, the latter tentatively assigned to the western species C. clarki) suggest they were also found on the other side of the Western Interior Seaway, on the landmass of Appalachia.

Species

The species Cimolomys clarki was named by Sahni in 1972. Fossil remains were found in Campanian-Maastrichtian (Upper Cretaceous) strata of Texas and Wyoming (United States). Possible remains have also come from New Jersey (USA). It probably weighed about 300 g, the same as a malnourished rat.

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, South Dakota and Wyoming (USA) and Saskatchewan, 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 (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 is in the collection of the University of Alberta.

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 from http://home.arcor.de/ktdykes/cimolod.htm MESOZOIC MAMMALS; "basal" Cimolodonta, Cimolomyidae, Boffiidae and Kogaionidae, an Internet directory

References

1. "PBDB Taxon".
2. Crane, Cynthia Danielle. (2011). "VERTEBRATE PALEONTOLOGY AND TAPHONOMY OF THE LATE CRETACEOUS (CAMPANIAN) BLADEN FORMATION, BLADEN COUNTY, NORTH CAROLINA".
3. (1992). "Alphadon (Marsupialia) and Multituberculata (Allotheria) in the Cretaceous of Eastern North America". Journal of Vertebrate Paleontology.