Mammalian faunal dynamics in Late Pleistocene Alberta, Canada

摘要

As a conduit for the passage of faunal and human species into the New World, the much-abused concept of the so-called "ice-free corridor" has served its purpose. The corridor concept has had an important bearing on discussions of zoogeography and paved the way for hypotheses about the recolonization of North America by mammalian species from Asia. Alberta-situated along the eastern slopes of the western Cordillera adjacent to the northern Great Plains-was long considered the ideal route for Late Pleistocene migrations into the North American heartland. Yet, a temporal hiatus in the large suite of bone and wood dates from central Alberta indicates that no corridor existed during the full-glacial, from about 22 000 to 12 000 BP. DNA, isotopic, and other studies of equids, bovids, cervids, ursids, mustelids and others confirm that animals flowed through Alberta, except during full glaciation. The mid-Wis-consinan fauna in Alberta indicates movements from both south and north, reflecting the absence of ice sheets during that interval. Migrations during the Last Glacial Maximum were precluded because the Cordilleran and Laurentide ice masses had coalesced to close the corridor. Finally, with the postglacial reopening of the passage, late-surviving proboscideans, muskoxen, horses, camels and lions-facing imminent extinction-may have formed a northwesterly bound megafaunal vanguard. Simultaneously, a thriving population of moose and wapiti drove southward from Beringia towards the mid-continent.