LEPORIDS (LAGOMORPHA, MAMMALIA) FROM THE CHADRONIAN (OLIGOCENE) DEPOSITS OF FLAGSTAFF RIM, WYOMING

Abstract

Deposits of Chadronian (early Oligocene) age at Flagstaff Rim, central Wyoming, have produced three taxa of leporids. Specimens referred to Palaeolagus temnodon are similar to topotypic samples from Pipestone Springs, Montana, although including a higher proportion of primitive vari- ants. Chadrolagus emryi n. gen. et sp. is closely related to Palaeolagus, but distinguished by reduction of buccal structures of anterior premolars. Megalagus brachyodon is a large, primitive lagomorph, one of several early forms lacking characters distinctive of either leporids or ochotonids, included in the Leporidae by convention. Variants occurring independently of each other within this sample, and changes in proportions and morphology of upper cheek teeth during wear, produce specimens resem- bling Montanolagus dicei, which is therefore synonymized with Megalagus brachyodon. C. emryi and P. temnodon appear to have been ecologically incompatible, though each coexisted with M. brac- hyodon.