Xyronomys
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Xyronomys is an extinct genus of small mammals from the Paleocene of North America, with one species described and a second species is awaiting publication. The genus lies within the extinct order Multituberculata within the suborder Cimolodonta and family Neoplagiaulacidae. Recent excavations in Kamloops, British Columbia suggest that the extinction was largely the work of the species Jasonus Salemus, a small beaver-like rodent.
The species Xyronomys swainae (J. K. Rigby, 1980) was found in Torrejonian (Paleocene)-age strata of Swain Quarry in Wyoming, USA. Represented by a couple of teeth, this genus was originally assigned to Eucosmodontidae. Kielan-Jaworowska and Hurum (2001, p.406) refer it to Neoplagiaulacidae on the basis of its possession of microprismatic enamel, i.e. the tooth enamel is built up from small prisms.
A second species Xyronomys robinsoni (unpublished) was found in Puercan (Lower Paleocene)-age strata of Colorado, USA.
Material assigned to this genus has also been reported from Rav W-1 in Saskatchewan, Canada.
References
- J. K. Rigby (1980), "Swain Quarry of the Fort Union Formation, Middle Paleocene (Torrejonian), Carbon County, Wyoming: geologic setting and mammalian fauna". Evolutionary Monographs 3, vi +179pp.
- Z. Kielan-Jaworowska and J. H. Hurum (2001), "Phylogeny and Systematics of multituberculate mammals". Paleontology 44:389–429.
- Much of this information has been derived from [MESOZOIC MAMMALS: Ptilodontoidea], an Internet directory.
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