Paracimexomys
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Paracimexomys is an extinct mammal that lived during the Cretaceous period, so it shared the world with dinosaurs. It was a member of the also extinct order Multituberculata. Remains are not extensive and come from North America. Some Romanian fossils were also tentatively assigned to this genus, though that now seems doubtful.
The genus Paracimexomys ("beside Cimexomys") was named by Archibald J.D. in 1982. It is also known as Cimexomys sp. (Sloan & Van Valen, 1965). P. fossils were originally referred to C., until it was realized they were different enough to justify a genus of their own.
Species
Species: ?Paracimexomys crossi Cifelli R.L. 1997
Remains have been found in the Upper Aptian-Albian (Lower Cretaceous) strata of the Antlers Formation of Oklahoma (USA). Based on a tiny tooth, this was the first reported Oklahoma Mesozoic mammal. It's also the oldest known member of the informal Paracimexomys group. The species name honours the prison officer Bobby Cross, who has found found this and other fossils.
Species: Paracimexomys magister (Fox R.C. 1971 and Archibald J.D. 1982). It is also known as Cimexomys magister (Fox 1971). Remains were found in the Upper Santonian (Upper Cretaceous) of Utah (USA). When alive, the animal probably weighed about 100 g (about four mice).
Species: Paracimexomys magnus (Sahni A. 1972; Archibald J.D. 1982)
Aka: Cimexomys magnus (Sahni A. 1972)
Place: Campanian (Upper Cretaceous) strata of the Judith River Formation in Montana (USA).
Species: Paracimexomys perplexus Eaton J.G. & Cifelli R.L., 2001
Place: Albian (late) - Cenomanian (early) (Upper Cretaceous) Cedar Mountain Formation of Utah.
Species: Paracimexomys priscus (Lillegraven J.A. 1969) Archibald JD, 1982. It is also known as Cimexomys priscus (Lillegraven J.A. 1969). Fossil remains were found in the Maastrichtian (Upper Cretaceous) of Hell Creek, Montana. Remains were first found in 1966. The holotype is in the collection of the University of Alberta, where the name Cimexomys is favoured. Weight is estimated to have been about 60 g.
Species: Paracimexomys robisoni Eaton J.G. and Nelson M.E. 1991
Place: Upper Cretaceous strata of the Cedar Mountain Formation of Utah. The type fossil is in the Oklahoma Museum of Natural History. This mouse-sized animal weighed about 25 g.
?Paracimexomys bestia seems to have possibly become Cedaromys bestia.
References
- Sahni (1972), Bulletin of the American Museum of Natural History 147(6).
- Cifelli (1997), "First notice on Mesozoic mammals from Oklahoma". Oklahoma Geology Notes 57, p.4-17.
- Archibald (1982), "A study of Mammalia across the Cretaceous-Tertiary boundary in Garfield County, Montana". Univ. of Calif Publ Geol Sci 122 xvi, p. 1-286.
- Eaton & Nelson (1991), Contributions to Geology, vol 29, no. 1.
- Eaton & Cifelli (2001), "Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah". Acta Palaeontologica Polonica 46(4), p.453-518.
- 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 [1] (http://home.arcor.de/ktdykes/cimolod.htm) MESOZOIC MAMMALS; 'basal' Cimolodonta, Cimolomyidae, Boffidae and Kogaionidae, an Internet directory.