The Holocene Paleoecology of Jenny Lake Area, Southwest Yukon, and Its Implications for Prehistory

The pollen stratigraphy of a core extracted from Jenny Lake, southwest Yukon, in 1984 has marked archaeological significance. Five palynological zones are identified as follows: Zone JL1, the oldest (ca. 12,500-9,500 B.P.), is a Betula shrub tundra assemblage; Zone JL2 (ca. 9,500-8,500 B.P.) an Alnus shrub tundra; Zone JL3 (ca. 8,500-4,500 B.P.) a Picea forest; Zone JL4 (ca. 4,500-2,000 B.P.) a Picea-Alnus woodland; and JL5 (ca. 2,000 B.P.-present) a Picea forest. The widely held belief that the Kluane-Aishihik area of the SW Yukon was covered by extensive grasslands well into the Holocene period is not supported by the palynology of the Jenny Lake Core. Instead, palynological evidence suggests that the area, which initially was a Betula shrub tundra, then Alnus shrub tundra, became a Picea-dominated forest by approximately 8,500 B.P. and remained forested to the present. The hypothesis stating early prehistoric hunters and gatherers in the SW Yukon were adapted to extensive Holocene grasslands until ca. 3,300-2,600 B.P. will have to be modified in view of these findings.Key words: Yukon, paleoecology, palynology, archaeologyMots clés: Yukon, paléoécologie, palynologie, archéologi

Morphometry of the teeth of western North American tyrannosaurids and its applicability to quantitative classification

Gross tooth morphology and serration morphology were examined to determine a quantifiable method for classifying tyrannosaurid tooth crowns from western North America. From the examination of teeth in jaws, tyrannosaurid teeth could be qualitatively assigned to one of five types based on the cross−sectional shape of the base of the tooth and characteristics of the mesial carina. A principal component analysis (PCA) revealed that much of the variance in tooth shape was a result of isometry, but some gross morphological variables exhibited strong positive allometry. Non−size associated factors were also important in determining tooth shape, particularly when data on denticle dimensions were considered in the analysis. While PCA identified important factors in variation, PCA ordination plots did not cluster the teeth into distinct, separate groupings based on taxon or bone of origin. The group classification functions determined by discriminant analysis, though not universally successful for classifying unidentified isolated teeth of all tyrannosaurids, do identify bone of origin of adult Albertosaurus, Daspletosaurus, and Gorgosaurus teeth at a statistically acceptable level