Quat. int. Quat. int. Evidence for Pleistocene gene flow through the ice-free corridor from extinct horses and camels from Natural Trap Cave, Wyoming Mitchell K. J. Bover P. Salis A. T. Mudge C. Heiniger H. Thompson M. Hockett B. Weyrich Laura S. Cooper A. Meachen J. A. 2023 research-article