. The Canadian field-naturalist. 250 The Canadian Field-Naturalist Vol. 89. 102 98 94 Figure 1. Location of the walrus fossil on Bathurst Island, Northwest Territories and nearby fossil localities of paleoenvironmental interest. 1. Odobenus rosmanis (walrus), 7320 ± 120 years (1-7796). 2. Hiatella arctica, Mya truncata (marine mollusk shells), 8440 ± 150 years (GSC-377). 3. Mya truncata (marine mollusk shells), 7670 ± 150 years (gsc-736). 4. Cetacea, probably Balaena mysticetus (whale), 7380 ± 140 years (gsc- 1193). Odobenus rosmarus. The relatively recent geological age of
. The Canadian field-naturalist. 250 The Canadian Field-Naturalist Vol. 89. 102 98 94 Figure 1. Location of the walrus fossil on Bathurst Island, Northwest Territories and nearby fossil localities of paleoenvironmental interest. 1. Odobenus rosmanis (walrus), 7320 ± 120 years (1-7796). 2. Hiatella arctica, Mya truncata (marine mollusk shells), 8440 ± 150 years (GSC-377). 3. Mya truncata (marine mollusk shells), 7670 ± 150 years (gsc-736). 4. Cetacea, probably Balaena mysticetus (whale), 7380 ± 140 years (gsc- 1193). Odobenus rosmarus. The relatively recent geological age of the fossil supports this iden- tification. Sex, Age, and Size Socially, walruses are usually segregated according to sex and age. Old males keep together, and adult females form herds with the young and immature animals of both sexes (Mansfield 1963, p, 25). An attempt was made to sex and age the animal represented by the fossil in the hope that it would provide knowledge about the type of walruses occupy- ing the central Canadian Arctic Islands about 7000 years ago. One of the most characteristic features of the walrus is its enlarged upper canine teeth or tusks. Generally, the size of the tusks in- creases with age, and females tend to have more slender tusks than males. As the fossil included a complete tusk, I tried to match it among a sample of nine recent walrus crania which had been aged by members of the Arctic Biological Station, Fisheries Research Board of Canada. Aging had been carried out by sectioning molariform teeth and counting their annual rings (Mansfield 1958, p. 35). This technique could not be tried on the fossil because the incisors and postcanines were missing. To facilitate comparisons, five graphs were constructed relating tusk dimensions (length, width, and circumference at the alve- olar margin, length of tusk exposed, and total length of the tusk) to age. The dimensions of. Please note that these images are extracted from scanned page images tha
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