Michael C. Wilson

Spatial Response of Mammals to Late Quaternary Environmental Fluctuations

Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene.

Late quaternary vertebrates and the opening of the ice-free corridor, with special reference to the genusbison

Abstract The ice-free iorridor opened physically in early deglaciation, after 14 ka BP, but at first was not necessarily passable in an ecological sense. One way to gauge the timing of its ‘ecological opening’ is to establish a chronology for the arrival of immigrant animal species. The bison have excellent potential because of the abundance of their remains. Late Pleistocene and Early Holocene bison finds from western Canada north to the Peace River area extend the known database and provide new insights. Bison of ‘southern’ appearance (referable toB. bison antiquus) were present as far north as the Peace River region until about 10 ka BP. Bison populations in western Canada apparently underwent a rapid change at that time, such that barely 500 years later, bison of ‘northern’ appearance (referable toB. bison occidentalis) were established. The rapidity and pervasiveness of this change seem to defy an evolutionary explanation rooted in punctuated equilibrium or phenotypic change, and could indicate a sudden population influx through the newly opened corridor. Thus far, no late-glacial bison in western Canada have been dated in excess of 11.5 ka BP, with the possible exception of material from Empress, Alberta. If a steppe-tundra was established before that time, the absence of bison with either southern or northern affinities seems inexplicable. Outburst floods have undoubtedly removed part of the record by scouring gravel fills from valleys, but it is doubtful that they completely obliterated the fossil record of a gregarious herbivore such as the bison.

A vonlea Phase Winter Fare at Lost Terrace, Upper Missouri River Valley of Montana: The Vertebrate Fauna

Abstract The nearly singular subsistence reliance by Late Prehistoric hunter-gatherers in the northwestern Plains on bison (Bison bison) is well-established. In a significant departure from that subsistence adaptation, a group of Avonlea Phase people occupying a floodplain of the upper Missouri River during late winter ca. 1200 radiocarbon years before present (RCYBP) procured a large number of pronghorn (Antilocapra americana). The excavated sample contains a minimum of 83 post-natal and 25 fetal pronghorn. Comprehensive breakage and utilization of carcass parts indicates that these people experienced significant nutritional stress. Whether Lost Terrace represents an example of patterned seasonal pronghorn hunting in the river bottom or was forced as a subsistence departure from reliance on river bottom wintering bison has not been determined at this time.

Microblade Cores from the Northwestern Plains at High River, Alberta, Canada

Abstract In the late 1950s, some 69 microblades and microblade fragments were collected from a small prairie blowout east of High River, Alberta (EdPk-1). In 1968, David Sanger analyzed these specimens, including distinctive ridge flakes, and attempted to reconstruct their manufacturing process without the benefit of any cores. The first microblade core recognized from the High River area was found in 1981 at site EdPk-3, approximately 2 km southeast of the original microblade discovery site. A second core was recovered at EdPk-3 in 1982 and two more cores from the High River area were subsequently recognized in existing collections. All four cores represent the same microblade technology and their morphology is essentially consistent with Sanger’s earlier interpretation, though they reveal new details. This technology is characterized by the use of ridge flakes to initiate blade detachment and by platform preparation with burin-like blows against a transversely flaked, upward curving platform ridge. The EdPk-3 cores were in surface association with artifacts primarily belonging to the Cody complex. The distinctive High River microblade cores appear most closely related to cores of the American Paleo-Arctic tradition, but probably represent a previously undescribed microblade technology that may have spread southward onto the Northwestern Plains.