Mylanodon rosei, a New Metacheiromyid (Mammalia: Palaeanodonta) from the Late Tiffanian (Late Paleocene) of Northwestern Wyoming

Authors

Ross Secord, University of Nebraska-LincolnFollow
Philip D. Gingerich, University of MichiganFollow
Jonathan I. Bloch, University of Michigan

Document Type

Article

Date of this Version

12-31-2002

Comments

Published in Contributions from the Museum of Paleontology, University of Michigan (December 31, 2002) 30(15): 385-399. Copyright 2002, the University of Michigan. Used by permission.

Abstract

Mylanodon rosei is a new genus and species of late Paleocene metacheiromyid palaeanodont from a new late Tiffanian locality, Y2K Quarry, in the Clarks Fork Basin, Wyoming. The type is an adult dentary with P₄ and a molariform double-rooted M₁. This provides the first evidence that molariform teeth were retained in early Metacheiromyidae. A second specimen is a juvenile dentary with a partial P₃ and an unerupted P₄. This is the first juvenile dentition known for a Paleocene metacheiromyid. The new specimens enable determination of dental homologies. Reduction of teeth in early metacheiromyids took place from back to front, opening the characteristic posterior diastema. Both Mylanodon and Propalaeanodon, a slightly older metacheiromyid, are intermediate morphologically and temporally between the older Tiffanian epoicotheriid Amelotabes and the younger Clarkforkian and Wasatchian metacheiromyid Palaeanodon. Propalaeanodon has a single-rooted M₁, a derived characteristic not found in Mylanodon, suggesting that two lineages are involved and Propalaeanodon was not ancestral to Mylanodon.