Tseng Zhijie Jack, Flynn John J
Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, United States of America.
Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, United States of America; Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024, United States of America.
PLoS One. 2015 Apr 29;10(4):e0124020. doi: 10.1371/journal.pone.0124020. eCollection 2015.
Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences.
咀嚼系统的性能直接影响进食和生存，因此人们常常提出适应性假说，通过功能形态变化来解释颅齿进化。然而，脊椎动物中颅骨形态与功能的“多对一”关联普遍存在，这表明生态和进化历史之间存在复杂的相互作用，导致形态与饮食之间的联系冗余。在此，我们研究了冠群食肉目（食肉哺乳动物中最多样化的类群）中具有不同饮食偏好的类群的颅骨生物力学特性之间的联系。我们测试了是否可以基于颅骨力学模拟模型区分超级食肉动物和杂食动物，以及这种饮食与生物力学的联系如何与形态相关。比较有限元分析和几何形态测量分析表明，预测咬合力相对于颅骨应变能呈正异速生长；这部分是通过较大颅骨模型中刚度的增加以及抵抗变形和位移的形状变化来实现的。尺寸标准化的应变能水平并不能反映进食偏好；相反，犬型类模型的应变能比猫型类模型更高。使用另外六个类群的已发表模型进行的敏感性分析强化了这种犬型类与猫型类的区分。尽管如此，结合咬合力 - 应变能曲线可以区分超级食肉动物和杂食性进食者。这些发现表明，尽管存在系统发育和异速生长效应，但颅骨生物力学特性与食肉动物进食偏好之间的联系可以明确界定和表征。将这种饮食与生物力学的联系模型应用于对一种已灭绝的食肉目干群和一个外群肉齿目物种的分析，为在具有相似进食偏好的冠群食肉目类群出现之前，类群进化为不同的超级食肉和杂食进食方式提供了生物力学证据。
