Records of the Fossil Mammal Sinclairella, Family Apatemyidae, From the Chadronian and Orellan   By: William Alvin Clemens

MUSEUM OF NATURAL HISTORY

Volume 14, No. 17, pp. 483 491, 2 figs. March 2, 1964

Records of the Fossil Mammal Sinclairella, Family Apatemyidae, From the Chadronian and Orellan

BY

WILLIAM A. CLEMENS, JR.

UNIVERSITY OF KANSAS LAWRENCE 1964

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Theodore H. Eaton, Jr.

Volume 14, No. 17, pp. 483 491, 2 figs. Published March 2, 1964

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY HARRY (BUD) TIMBERLAKE, STATE PRINTER TOPEKA, KANSAS

1964

29 8587

Records of the Fossil Mammal Sinclairella, Family Apatemyidae, From the Chadronian and Orellan

BY

WILLIAM A. CLEMENS, JR.

Introduction

The family Apatemyidae has a long geochronological range in North America, beginning in the Torrejonian land mammal age, but is represented by a relatively small number of fossils found at a few localities. Two fossils of Orellan age, found in northeastern Colorado and described here, demonstrate that the geochronological range of the Apatemyidae extends into the Middle Oligocene. Isolated teeth of Sinclairella dakotensis Jepsen, part of a sample of a Chadronian local fauna collected by field parties from the Webb School of California, are also described.

I thank Mr. Raymond M. Alf, Webb School of California, Claremont, California, and Dr. Peter Robinson, University of Colorado Museum, Boulder, Colorado, for permitting me to describe the fossils they discovered. Also Dr. Robinson made available the draft of a short paper he had prepared on the tooth found in Weld County, Colorado; his work was facilitated by a grant from the University of Colorado Council on Research and Creative Work. I also gratefully acknowledge receipt of critical data and valuable comments from Drs. Edwin C. Galbreath, Glenn L. Jepsen, and Malcolm C. McKenna who is currently revising the Paleocene apatemyids and studying the phylogenetic relationships of the family. The prefixes of catalogue numbers used in the text identify fossils in the collections of the following institutions: KU, Museum of Natural History, The University of Kansas, Lawrence; Princeton, Princeton Museum, Princeton, New Jersey; RAM UCR, Raymond Alf Museum, Webb School of California, Claremont, California (the permanent repository for these specimens will be the University of California, Riverside); and UCM, University of Colorado Museum, Boulder, Colorado. The system of notations for teeth prescribed for use here is as follows: teeth in the upper half of the dentition are designated by a capital letter and a number; thus M2 is the notation for the upper second molar; teeth in the lower half of the dentition are designated by a lower case letter and a number; thus p2 is the notation for the lower second premolar.

Family APATEMYIDAE Matthew, 1909

Genus =Sinclairella= Jepsen, 1934

=Sinclairella dakotensis= Jepsen, 1934

The type of the species, Princeton no. 13585, was discovered in Chadronian strata of the upper part of the Chadron Formation cropping out in Big Corral Draw, approximately 13 miles south southwest of Scenic, in southwestern South Dakota (Jepsen, 1934, p. 291). Detailed descriptions of the type specimen are given in papers by Jepsen (1934) and Scott and Jepsen (1936). Isolated teeth of Chadronian age referable to Sinclairella dakotensis have been discovered subsequently at a locality in Nebraska and fossils of Orellan age, also referable to S. dakotensis , have been collected at two localities in Colorado. The sample from each locality is described separately.

Sioux County, northwestern Nebraska

Material. RAM UCR nos. 381, left M1; 598, left m2; 1000, right m1; 1001, right m2; 1079, right m2; 1674, right M2; and 3013, left m2.