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Evolution in Yoderimyinae (Eomyidae: Rodentia), with new material from the White River Formation (Chadronian) at Flagstaff Rim, Wyoming

Published online by Cambridge University Press:  20 May 2016

Robert J. Emry  and
William W. Korth
Robert J. Emry
Affiliation:
1Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560
William W. Korth
Affiliation:
2Department of Geological Sciences, University of Rochester, Rochester, New York 14625, and Department of Geosciences, Hobart and William Smith Colleges, Geneva, New York 14456
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Abstract

Three species of Yoderimyinae (Eomyidae: Rodentia) are recognized from the lower part of the White River Formation (early to medial Chadronian) in the Flagstaff Rim area, Wyoming. The new material allows an improved diagnosis for the subfamily. The enamel microstructure of Yoderimyinae supports its inclusion in the Eomyidae.

A new genus, Zemiodontomys, is established for Yoderimys burkei Black, and new material, including upper dentition, is referred to this species. This genus differs from Yoderimys in having higher crowned and more lophodont teeth and in lacking P3. A second new genus, Litoyoderimys, is established for Yoderimys lustrorum Wood, and a new species, L. auogoleus, is referred to the genus. This genus has lower crowned, more cuspate teeth than Yoderimys.

Through early and medial Chadronian time, evolution in yoderimyines includes the following morphologic transformations: increase in size; increase in crown height and lophodonty of cheek teeth; reduction of P3 (from double-rooted, to single-rooted, to absent); increase in relative size of P4 and p4; and increased longitudinal torsion of the mandible.

Type
Research Article
Information
Journal of Paleontology , Volume 67 , Issue 6 , November 1993 , pp. 1047 - 1057
Copyright
Copyright © The Paleontological Society 

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