Abstract

Communal hunting allows some modern canids to catch large and powerful prey. As opposed to felids, for example, Recent canids have a limited ability to grapple and subdue prey by using their forelimbs. Instead, they engage in sustained pursuit predation and the success rate during this activity typically increases with the number of individuals participating in the hunt. Clearly, such behaviors do not fossilize directly and have to be inferred from anatomy. This paper focuses on how social pack-hunting in large-bodied fossil canids can be determined and the potential for it among Tertiary canids (Canidae, Carnivora). Craniodental adaptations for handling and killing large prey and forearm utility in running and grappling are investigated by principal components and canonical variates analyses. I also test whether fossil canids responded to predation of large prey by evolving the same morphological traits as their Recent pursuit-type relatives. The analyses show that small and large members of the Recent Caninae share similar craniodental morphologies. However, the same pattern is not present in the fossil subfamilies Borophaginae and Hesperocyoninae. In the latter, large representatives are characterized by being relatively short-faced with reduced anterior premolars and enlarged posterior premolars, thus approaching a “pantherine-like” configuration. These traits are interpreted as an adaptation for killing prey with felid-like canine bites. The elbow joints of large canids also do not converge on a single morphotype. All analyzed species of borophagines and hesperocyonines have retained the ability to supinate their forearms, unlike Recent large Caninae. It is therefore likely that manual manipulation was part of their hunting behavior, thus removing an essential part of the argument for social pack-hunting in these forms, as the benefits of such a strategy become less obvious. An association between the origin of pack-pursuit “wolf avatars” and the origin and evolution of grass-dominated ecosystems is hypothesized. The results presented here clearly suggest that Recent large canids are poor ecological, morphological, and behavioral analogs for their large fossil relatives.

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