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Distinct Predatory Behaviors in Scimitar- and Dirk-Toothed Sabertooth Cats

2018; Elsevier BV; Volume: 28; Issue: 20 Linguagem: Inglês

10.1016/j.cub.2018.08.012

1879-0445

Borja Figueirido, Stephan Lautenschlager, Alejandro Pérez‐Ramos, Blaire Van Valkenburgh,

Wildlife Ecology and Conservation

Over the Cenozoic, large cat-like forms have convergently evolved into specialized killers of "megaherbivores" that relied on their large, and laterally compressed (saber-like) canines to rapidly subdue their prey [1Bohlin B. Food habit of the machaerodonts, with special regard to S. fatalis.Bull. Geol. Inst. Upsala. 1940; 28: 156-174Google Scholar, 2Emerson S.B. Radinsky L. Functional analysis of sabertooth cranial morphology.Paleobiology. 1980; 6: 295-312Crossref Scopus (164) Google Scholar, 3Van Valkenburgh B. Deja vu: the evolution of feeding morphologies in the Carnivora.Integr. Comp. Biol. 2007; 47: 147-163Crossref PubMed Scopus (218) Google Scholar, 4Andersson K. Norman D. Werdelin L. Sabretoothed carnivores and the killing of large prey.PLoS ONE. 2011; 6: e24971Crossref PubMed Scopus (32) Google Scholar, 5Palmqvist P. Martínez-Navarro B. Arribas A. Prey selection by terrestrial carnivores in a lower Pleistocene paleocommunity.Paleobiology. 1996; 22: 514-534Crossref Scopus (120) Google Scholar]. Scimitar- and dirk-toothed sabertooths are distinct ecomorphs that differ in canine tooth length, degree of serration, and postcranial features indicative of dissimilar predatory behavior [6Kurtén B. Pleistocene Mammals of Europe. Weidenfeld and Nicolson, 1968Google Scholar, 7Martin L.D. Functional morphology and the evolution of cats.Trans. Nebr. Acad. Sci. 1980; 8: 141-154Google Scholar, 8Slater G.J. Van Valkenburgh B. Long in the tooth: evolution of sabertooth cat cranial shape.Paleobiology. 2008; 34: 403-419Crossref Scopus (82) Google Scholar, 9Martin L.D. Babiarz J.P. Naples V.L. Hearst J. Three ways to be a saber-toothed cat.Naturwissenschaften. 2000; 87: 41-44Crossref PubMed Scopus (44) Google Scholar, 10Meachen-Samuels J.A. Van Valkenburgh B. Radiographs reveal exceptional forelimb strength in the sabertooth cat, Smilodon fatalis.PLoS ONE. 2010; 5: e11412Crossref PubMed Scopus (51) Google Scholar, 11Anyonge W. Locomotor behaviour in Plio-Pleistocene sabre-tooth cats: a biomechanical analysis.J. Zool. (Lond.). 1996; 238: 395-413Crossref Scopus (74) Google Scholar, 12Antón M. Sabertooth. Indiana University Press, 2013Google Scholar, 13Gonyea W.J. Behavioral implications of saber-toothed felid morphology.Paleobiology. 1976; 2: 332-342Crossref Scopus (90) Google Scholar]. Despite these differences, it is assumed that they used a similar "canine-shear" bite to kill their prey [14Akersten W.A. Canine function in Smilodon (Mammalia, Felidae, Machairodontinae).Contrib. Sci. 1985; 356: 1-22Google Scholar, 15Antón M. Galobart A. Neck function and predatory behavior in the scimitar toothed cat H. serum latidens (Owen).J. Vertebr. Paleontol. 1999; 19: 771-784Crossref Scopus (81) Google Scholar]. We investigated the killing behavior of the scimitar-toothed Homotherium serum and the dirk-toothed Smilodon fatalis using a comparative sample of living carnivores and a new quantitative approach to the analysis of skull function. For the first time, we quantified differences in the relative amount and distribution of cortical and trabecular bone in coronal sections of skulls to assess relative skull stiffness and flexibility [16Carter D.R. Hayes W.C. Compact bone fatigue damage--I. Residual strength and stiffness.J. Biomech. 1977; 10: 325-337Abstract Full Text PDF PubMed Scopus (226) Google Scholar, 17Guede D. González P. Caeiro J.R. Biomecánica y hueso (I): Conceptos básicos y ensayos mecánicos clásicos.Revista de Osteoporosis y Metabolismo Mineral. 2013; 5: 43-50Crossref Google Scholar, 18Reddy S. Dischino M. Soslowsky L.J. Khurana J. Biomechanics-Part I. Bone Pathology. Humana Press, New York2009: 61-68Google Scholar, 19Mostakhdemin M. Amiri I.S. Syahrom A. Introduction of bone study.in: Mostakhdemin M. Sadegh Amiri I. Syahrom A. Multi-axial Fatigue of Trabecular Bone with Respect to Normal Walking. Springer, 2016: 1-4Crossref Scopus (1) Google Scholar]. We also use finite element analysis to simulate various killing scenarios that load skulls in ways that likely favor distinct proportions of cortical versus trabecular bone across the skull. Our data reveal that S. fatalis had an extremely thick skull and relatively little trabecular bone, consistent with a large investment in cranial strength for a stabbing canine-shear bite. However, H. serum had more trabecular bone and most likely deployed an unusual predatory behavior more similar to the clamp-and-hold technique of the lion than S. fatalis. These data broaden the killing repertoire of sabertooths and highlight the degree of ecological specialization among members of the large carnivore guild during the Late Pleistocene of North America.