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Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah

2001; Institute of Paleobiology; Volume: 46; Issue: 4 Linguagem: Inglês

1732-2421

Jeffrey G. Eaton, Richard L. Cifelli,

Bat Biology and Ecology Studies

Herein we describe the oldest well-sampled multituberculate assemblage from the Cretaceous of North America. The fauna is dated at 98.37 Ma and thus approximates the Albian-Cenomanian (Early-Late Cretaceous) boundary. The multituberculate fauna is diverse. Two of the multituberculates (Janumys erebos gen. et sp. n. and an unidentified taxon) are provisionally placed among 'Plagiaulacida'. Another taxon, Ameribaatar zofiae gen. et sp. n., is of uncertain subordinal affinities. The remaining multituberculates appear to represent the advanced suborder Cimolodonta and fall within the 'Paracimexomys group'. We rediagnose Paracimexomys on the basis of the type species, P. priscus, and refer to other species as cf. Paracimexomys (including cf. P. perplexus sp. n.). A revised diagnosis is also provided for Cenomanian Dakotamys. A previouslydescribed species from the Cedar Mountain Formation is placed in Cedaromys gen. n. as C. bestia, together with C. pawus sp. n. Bryceomys is represented in the fauna by B. intermedius sp. n. Relationships of Paracimexomys-group to later taxa remain obscure. However, Bryceomys and Cedaromys share a number of features with Cimolodontidae. Given these resemblances, together with the fact that Cimolodontidae retain certain plesiomorphies (stout lower incisor, gigantoprismatic enamel) with respect to Ptilodontoidea (to which they are commonly referred), we suggest that Cimolodontidae may have arisen from a clade within the 'Paracimexomys group', independent of ptilodontoids.