Meeting Abstract

40.4  Tuesday, Jan. 5  Evolution of locomotion and predation in saber-toothed cats ORCUTT, J.D.*; LEVERING, D.; DAVIS, E.B.; University of Oregon; Oklahoma State University; University of Oregon jorcutt@uoregon.edu

An understanding of the ecological roles of organisms within paleocommunities is critical to tracking ecosystem change through time. For many extinct mammalian taxa, these roles can be reconstructed through extrapolation from the behavior of related modern species. Some extinct taxa were morphologically and, presumably, ecologically distinct from any extant mammals, complicating reconstruction of their ecological roles. A classic example is the felid subfamily Machairodontinae (saber-toothed cats), species of which represent a morphotype with no modern analog. Several hypotheses of predatory behavior within this group have been suggested, largely based on skull biomechanics of its best-known member, Smilodon fatalis. We approach this debate from a novel perspective, using an already-developed morphospace model based on ratios of proximal and distal limb bones, to examine North American machairodontines. Our results suggest that all machairodontines were non-cursorial ambush predators, but that the degree of cursoriality does not remain constant through time. Early taxa, such as the Miocene Machairodus, show limb proportions more similar to those of modern felids, while the Pleistocene Smilodon approaches bears in its limb ratios. This apparent decrease in cursoriality may indicate a concurrent increase in sociality in Smilodon.