Julie A. Meachen; Adrianna C. Janowicz; Jori E. Avery; Rudyard W. Sadleir

“ The Pleistocene coyotes had an overall robust mandible with an increased shearing arcade and a decreased grinding arcade, adapted for carnivory and killing larger prey; whereas the modern populations show a gracile morphology with a tendency toward omnivory or grinding. The earliest Holocene populations are intermediate in morphology and smallest in size. These findings indicate that a niche shift occurred in coyotes at the Pleistocene/Holocene boundary – from a hunter of large prey to a small prey/more omnivorous animal. ”

“ Here we show, on average, Pleistocene coyotes were experiencing stronger dorso-ventral forces on the mandible during feeding and hunting than living coyotes. This suggests that Pleistocene coyotes were hunting larger prey more frequently and incorporating harder food (such as bone) into their diet. While it is possible that coyotes were scavenging more than hunting, the shape of the thickened anterior corpus suggests that they were also hunting with a higher frequency. ”

“ The intermediate condition in the earliest Holocene coyotes, plus mandibular morphology that closely resembles the Pleistocene specimens, but with negative allometry, suggests an adapting population, rather than immigration from elsewhere. However, we cannot test this hypothesis without a DNA analysis.
Recent coyotes have large but gracile mandibles compared with the older populations. They also have a longer grinding arcade and a shorter shearing arcade compared to earlier populations. ”

“ Extinction events do not just affect the species that go extinct, but also affect many of the species that remain. For coyotes, interactions between closely related competitors are likely the driving force behind major evolutionary changes. ”

“ Additionally, Recent coyote populations also do not seem to follow Bergmann’s rule – a positive relationship between latitude and body size [9] , [10] (sometimes presented as a negative relationship between climate and body size) . ”

“ Neoteny in pit 10 coyotes may be the result of truncated growth in the absence of the large quantity of protein that was available in the Pleistocene. This negative trend continues into the Recent coyote populations. ”

“ LACMHC, Rancho La Brea, Page Museum Hancock collection, Los Angeles, CA.
We analyzed C. latrans mandibular morphology using 2D geometric morphometrics (GM) . Mandibular morphology captures many attributes of prey-killing and feeding style in carnivores [14] , [19] , and mandible fossils are numerous at RLB. Mandibles were digitized from digital photographs of the labial view of hemi-mandibles of C. latrans. ”

“ Skeletal and dental predictors of body mass in carnivores. In: Damuth J, MacFadden B, editors. Body size in mammalian paleobiology: estimation and biological implications. Cambridge: Cambridge University Press. 181–206.↑ Gese EM, Rongstad OJ, Mytton WR (1988) Relationship between coyote group-size and diet in Southeastern Colorado. Journal of Wildlife Management 52:647–653 .↑ Ogle TF (1971) Predator prey relationships between coyotes and white-tailed deer. Northwest Science 45:213–218 .↑ Ozoga JJ, Harger EM (1966) Winter activities and feeding habits of northern Michigan coyotes. ”