Cimolodon

Cimolodon is a mammal genus from the Upper Cretaceous of North America. It was a member of the extinct order of Multituberculata within the Suborder of Cimolodonta, and possibly the family Cimolodontidae.

Genus: Cimolodon Marsh OC, 1889
Aka: Allacodon (partly); Cimolomys (partly); Halodon Marsh, 1889; Nanomys ('small mouse') Marsh, 1889; Nanomyops Marsh, 1892; Ptilodus partly
Remarks: Whilst some Cimolomys material has indeed been referred to Cimolodon, that doesn't necessarily mean that the whole genus, or a particular species has. It could well be that one-time Cimolodon fossils have subsequently also been referred to Cimolomys as well. If you find this somewhat confusing, so do I.
"Cimolodon seems to be more closely related to the Paracimexomys group than are other ptilodontoideans," (Kielan-Jaworowska & Hurum, 2001, p.404). Odd as it may sound, the placement of this genus within Cimolodontidae is tentative. Its tooth enamel is 'gigantoprismatic', whilst its possible relatives favour a 'microprismatic' style, (p.418 of the same paper).

Species: Cimolodon electus Fox RC, 1971
Place: Upper Milk River Formation, Alberta
Country: Canada
Age: Upper Cretaceous
Remarks: The holotype[?] is in the collection of Alberta University. Possible finds have been reported from New Mexico. Weight guestimate = 195g, (about half a rat).
Reference: Fox (1971), Early Campanian multituberculates ( Mammalia: Allotheria) from the upper Milk River Formation, Alberta. Canadian J of Earth Sci 8: 916.

Species: Cimolodon nitidus Marsh OC, 1889
Aka: Allacodon lentus Marsh, 1889; Allacodon rarus Marsh, 1892; Cimolomys bellus Marsh, 1889; Cimolomys digona Marsh, 1899; Cimolomys gracilis Marsh, 1889; Cimolomys minutes; Cimolomys nitidus; Halodon serratus Marsh, 1889; Nanomyops minitus Marsh, 1892; Nanomys minitus Marsh 1889; Ptilodus serratus Gidley, 1909
Place: Lance Formation, Wyoming, Utah, Montana & S Dakota
Country: USA & Canada
Age: Upper Cretaceous
Remarks: Weighed about 230g. Simpson referred this species to C. gracilis in 1929. Subsequently, it's been reallocated to C. nitidus by various authors, apparently beginning with Clemens in 1963.
References: Marsh (1889,) Discovery of Cretaceous Mammalia. Am. J. Sci. (3), 38, p.177-180.
Simpson (1929), American Mesozoic Mammalia. Mem. Peabody Mus. Nat. Hist. iii (i), p.1-235.

Species: Cimolodon parvus Marsh OC, 1892
Place: Lance Formation, Wyoming
Country: USA
Age: Upper Cretaceous
Remarks: This was first tentatively referred to P. cf. carvus, (Krause, 1980). Weight of about 190g.
Reference: Marsh (1892), Discovery of Cretaceous Mammalia. Pt. III. Am. J. Sci. (3) xliii, p.249-262.

Species: Cimolodon similis Fox RC, 1971
Place: Utah
Country: USA
Age: Upper Cretaceous
Remarks: This holotype[?] is also in Alberta University. A body weight of about 5 standard mice, 125g.
Reference: Fox (1971), Canadian J of Earth Sci 8: 916.

Page references: Kielan-Jaworowska Z & Hurum JH (2001), Phylogeny and Systematics of multituberculate mammals. Paleontology 44, p.389-429.

(This information has been derived from [1] (http://home.arcor.de/ktdykes/ptilodon.htm) MESOZOIC MAMMALS; Ptilodontoidea, an internet directory. As that's my webpage, there are no issues of copyright. Trevor Dykes)