Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
REVIEW OF THE NORTH AMERICAN FOSSIL CRICETINE RODENTS (MURIDAE: MAMMALIA)
Abstract
Eighty-three species of fossil cricetines, arranged in twenty-six genera, have been described from the North American Tertiary and Pleistocene alone, and many of these are shown to be invalid.The cricetines were especially abundant in both North America and Eurasia in the Medial to Late Oligocene and in the Medial Pliocene to Recent, but in Europe also in the Miocene. Their appearance in South America seems to have been during the second New World expansion. Simmys of the Late Eocene of California is the probable ancestor of all cricetines.The genus Paracricetodon first appeared in the Early to Medial Oligocene of Europe and in the Medial Oligocene of North America. There is every reason to believe that this genus was the ancestor of many European and most North American forms. In the Medial Oligocene of North America, it developed parallel to the well-known genus Banys, and it may have been the ancestral stock for both Euys and Scottimus. Paracricetodon may have become extinct in the Late Miocene, but it should be considered as a possible ancestor of some later cricetines.Fossil cricetines have been differentiated almost exclusively on dental characters, but the extreme variability of the Banys dentition shows that this may not be wholly reliable. In this study of the exceptionally rich materials of The University of Nebraska State Museum, nine species of Bunys so established are shown to be invalid variants of Eunys elegans. In the Medial Oligocene, Euys may have given rise to the genus Leidvays, that lived into the Medial Miocene. Both Buys and Scottimus seem to have become extinct at least in the Early Miocene. Paracricetodon may have been the ancestor of both Asiatic and North American representa- tives of the genus Schaubeuys. The relationships of the Late Miocene Horatioays are unknown. The taxonomic position of the Early to Medial Miocene Paciculus is also problematical; it may be a zapodid or sicistine.The Late Miocene and Early Pliocene Copenys seems to be a close relative or ancestor of Peromyscus, even though this latter genus has been reported also from the Miocene and Pliocene. The Pliocene Miochomys may have given rise to Onychomys. The enigmatic Macrognathomys from the Pliocene of Nevada bears no evident relationship to other cricetines.The Recent North American genera, and also those of South America, make their first appearance during the second great New World expansion of the cricetines, from the Medial Pliocene to Recent. The genera Parahodomys and Symmetrodontonys are known only from the Pleistocene deposits of North America. The genera Neotoma, Sigmodon, Orysonys, and Reithrodontomys have no known Tertiary ancestors. Baiomys is so similar to Peromyscus that it may be a small race of the latter.
Subject Area
Geology
Recommended Citation
ALKER, JULIUS, "REVIEW OF THE NORTH AMERICAN FOSSIL CRICETINE RODENTS (MURIDAE: MAMMALIA)" (1967). ETD collection for University of Nebraska-Lincoln. AAI6710653.
https://digitalcommons.unl.edu/dissertations/AAI6710653