Distinct predatory behaviors in scimitar- and dirk-toothed sabertooth cats

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 [1-5]. 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 [6-13]. Despite these differences, it is assumed that they used a similar ‘canine-shear’ bite to kill their prey [14,15]. 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 [16-19]. We also use finite element ana..., ,新生代时期，多支大型猫型类群趋同演化出特化的巨型草食动物猎手：它们依靠硕大且侧扁（剑齿状）的犬齿，快速制服猎物[1-5]。弯刀齿与刃齿剑齿虎类为两类截然不同的生态形态类群，二者在犬齿长度、齿面锯齿程度以及反映捕食行为差异的颅后骨骼特征上均存在显著区别[6-13]。尽管存在上述差异，学界此前普遍认为二者采用相似的「犬齿剪切」咬合方式完成猎杀[14,15]。本研究以现生食肉动物为对照样本，结合全新的颅骨功能定量分析方法，对弯刀齿类的巨剑齿虎（Homotherium serum）与刃齿类的致命刃齿虎（Smilodon fatalis）的猎杀行为展开了探究。本研究首次对颅骨冠状切面中密质骨（cortical bone）与松质骨（trabecular bone）的相对含量及分布差异进行量化，以此评估颅骨的相对刚度与柔韧性[16-19]。本研究同时采用有限元分析（finite element analysis）……