Appendix I

Abstract

In order to test the hypothesis that buffalo jumping was limited to a certain time of the year the age of the animals at time of death had to be determined. This was done by means of lower tooth eruption and wear from a sample of 251 complete or fragmentary mandibles from which aging data could be obtained. The method of tooth sectioning to determine layers of cemen tum was not attempted. If the jumping period was limited to the fall of the year the animals should reflect yearly age grouping, assuming that the schedule of tooth eruption and time of birth was nearly the same for all animals. Assuming a peak of calving toward the last of April and the first of May and a jumping season from late September to early November, the age grouping of the buffalo should cluster at about .5 years, 1.5 years, 2.5 years, 3.5 years, etc. The sample would have to be large to allow for the occasional late calves that normally appear. The younger animals are the most reliable for purposes of aging, since tooth eruption can be used. In the older age groups, reliance must be made on tooth wear which should be valid in a single area but which can change rapidly over geographical areas. Domestic animals demon strate different degrees of tooth wear depending upon existing range conditions. The incisor teeth are the most sensitive guide to aging, but due to butchering practices and loss of the anterior parts of the mandible through bone decomposition, they were usually not available. Attempts to use mandibles from the various breeds of domestic cattle were not successful. Bison in general are a longer-lived animal than Bos and there are also some differences in tooth eruption schedules, especially with the incisors. It was apparent from this that specimens of known age were necessary and these were obtained from several different buffalo herds in Wyoming. By far the most informative group of specimens was obtained through the courtesy of Arthur Busskohl, manager of the Durham Meat Company near Gillette, Wyoming, who maintains a large commercial buffalo herd and butchers large numbers of animals of known age. Entire skulls were skinned and saved intact so that large numbers were available, mostly in the 21/2 to 31/2 year age groups with lesser numbers available in the 1/2, 11/2, and old age groups. Another sample of reasonably well known age was made available by the Zoology Department of the University of, Wyoming, which had nearly a hundred mandibles from the Yellowstone National Park herd. A small but valuable sample, including a three day old calf and a 4.6 year old bull were obtained from George Crouse, a buffalo raiser near Lara mie, Wyoming. By using known-age samples, the mandibles from the Glenrock Jump fell in general age categories as follows: