THE INSECTIVORES OF THE REXROAD FAUNA, UPPER

Le résumé fourni par la source

Six genera of insectivores were recovered with associated vertebrates from a deposit of the upper Pliocene, Rexroad formation, Meade County, Kansas. The insectivores are Hesperoscalops, a mole, which is probably ancestral to the recent genus Scalopus; the following genera of shrews: Sorex, Paracryptotis, Cryptotis?, Blarina and Notiosorex. Three species are described as new. The upper Pliocene distribution of the shrews in North America was different than at the present. This difference is accounted for by the climatic change which has occurred in the region where the fossils were recovered. During the past five years considerable data has been accumulated .upon the rather poorly known insectivores from the upper Pliocene, Rexroad fauna of southwestern Kansas. The distribution of the genera of shrews in the upper Pliocene is an entirely different picture than that at the present time. Much of this difference in distribution is due to climatic change in the area and to the shifting of the ranges of forms during the Pleistocene. The specimens herein reported were all taken from a small exposure of the Rexroad formation in Fox Canyon, Meade County, Kansas, unless otherwise stated. A discussion of the associated mammalian fauna and of the Rexroad formation is given by Hibbard (1950). Only one species of mole is known in the Rexroad fauna. Five genera and five species of shrews were recovered from an area less than fifteen feet long, within a vertical range of two feet, and extending back into the exposure approximately three feet. At the present time only one species of mole, Scalopus aquaticus intermedius (Elliot), and one shrew, Cryptotis parva (Say) are known to live in that part of the High Plains. I am particularly indebted to the University of Michigan Museum field parties of the summers of 1950 and 1951; and to the Kansas Forestry, Fish and Game Commission for living quarters and for permission to use stream facilities for the recovery of the fossil vertebrates. Mr. J. D. Center, of the Triangle T Ranch, Plains, Kansas, who has leased the land of the late Alexander W. Adams, kindly gave us permission to 21 continue the collection of fossils and the study of deposits on this land. This study was started in the summer of 1936, with the permission and cooperation of Alex(ander) W. Adams of Maple Hill, Kansas. This work was aided by the loan of specimens under the care of Dr. W. H. Burt, University of Michigan; Mr. Stanley P. Young and Miss Viola S. Schantz, United States Fish and Wildlife Service; and Dr. Robert W. Wilson, University of Kansas, who also gave permission to figure the specimen of Sorex taylori and who checked certain characters on specimens in the collections at the University of Kansas. The line drawings were made by W. C. Sherman and Jane S. Mengel. All specimens are in the University of Michigan Museum collection unless otherwise stated. The illustrations of this paper were made possible by the financial support accorded to the writer by the Faculty Research Fund of the Univer-

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.