Canis dirus preserved in the late Pleistocene Rancho La Brea tar seep deposits display a remarkably high incidence of teeth broken in life as compared with modern species. This might reflect greater carcass utilization in the Pleistocene relative to the present. Here we compare tooth fracture frequencies in C. dirus between two localities at Rancho La Brea, Pit 13 (about 15 ka) and Pit 61/67 (about 12 ka). Results indicate that Pit 13 C. dirus exhibited heavier tooth wear and fractured their teeth about three times more often than those of the younger Pit 61/67. This might reflect a difference in diet between the two periods or a greater preservation of older individuals (which are more likely to have broken teeth) in Pit 13. To test for differences in the mortality profiles of the two pits, we estimated individual age C. dirus from pulp cavity dimensions of lower canine teeth, as measured from radiographs of preserved mandibles. We first verified the validity of the approach using a sample of extant Canis latrans that had been previously aged using cementum counts. Pulp cavity analysis of the C. dirus indicated no significant difference between pits in the age structure of the preserved populations. Consequently, it appears that feeding behavior of C. dirus differed in the latest Pleistocene in that bone consumption declined. Pulp cavity analysis has great potential for further studies of population parameters, such as mortality profiles, of extinct carnivorans. It is easy, non-destructive, and provides a continuum of age values rather than discrete categories.
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