New rodents (Mammalia, Rodentia, Cricetidae) from the Verde Fauna of Arizona and the Maxum Fauna of California, USA, early Blancan Land Mammal Age

Everett H. Lindsay and Nicholas J. Czaplewski

ABSTRACT

The cricetid rodent Postcopemys repenningi, new genus and new species, is described from the Verde fauna in Arizona and the Maxum fauna in California. Two other rodents, Postcopemys maxumensis, new species, and Jacobsomys dailyi are reported herein from the Maxum fauna. Jacobsomys dailyi is described and Postcopemys valensis is reported (May et al. 2011) from the Warren fauna in southern California. Jacobsomys verdensis had been reported from the Verde fauna by Czaplewski (1987a). These three faunas (the Warren and Maxum faunas in California and the Verde fauna in Arizona) are considered close to the Blancan/Hemphillian boundary, and the two genera Postcopemys and Jacobsomys are important small mammal taxa whose stage of evolution should prove useful for demonstrating the morphologic transition between Copemys and extant Peromyscus via Postcopemys, and between Bensonomys and extant Oryzomys via Jacobsomys, as well as for ordering mammalian faunas relative to the Blancan/Hemphillian boundary.

Everett H. Lindsay. Department of Geosciences, Gould-Simpson Building, University of Arizona, Tucson, Arizona 85721 USA
Nicholas J. Czaplewski. Oklahoma Museum of Natural History, 2401 Chautauqua Avenue, University of Oklahoma, Norman, Oklahoma 73072 USA

KEY WORDS: Cricetidae; Verde; Maxum; Blancan; fossils; Pliocene

PE Article Number: 14.3.29A
Copyright: Society of Vertebrate Paleontology November 2011
Submission: 15 June 2007. Acceptance: 25 February 2011