Paleoecology and taphonomy of late Pleistocene Dicrostonyx from Wyoming caves

Abstract

Dicrostonyx has been reported from seven Late Pleistocene localities in Wyoming. All localities are stratified, highly fossiliferous and detail a similar sequence of faunal changes through the late Pleistocene and early Holocene. Three of these are found in the northern Bighorn Mountains: Natural Trap Cave, Prospects Shelter and Shutdown Shelter. Little Box Elder and Bell Caves are found in the Laramie Range while Little Canyon Creek Cave and Bush Shelter are found in the southern Bighorn Mountains. These latter four localities contain sizable samples of Dicrostonyx teeth which have not been previously described. All four of these faunas date older than 12,000 years B.P. A review of the physiology of Dicrostonyx shows the genus is adapted to cold, moist climates and should not be used as an indicator of an environment similar to the modern High Arctic tundra. Preliminary examination of occlusal surfaces of Dicrostonyx teeth from these four localities suggests a taphonomy resulting from both diurnal and nocturnal birds of prey, similar to studies on the Dicrostonyx remains from Natural Trap Cave. There remains a slight possibility for at least some of the Dicrostonyx remains to be accumulated due to mammalian carnivore predation.