Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, 37235-1634, USA.
Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, Tennessee, 37235-1805, USA.
Sci Rep. 2020 Jun 1;10(1):8809. doi: 10.1038/s41598-020-65586-w.
Paleontologists and paleoanthropologists have long debated relationships between cranial morphology and diet in a broad diversity of organisms. While the presence of larger temporalis muscle attachment area (via the presence of sagittal crests) in carnivorans is correlated with durophagy (i.e. hard-object feeding), many primates with similar morphologies consume an array of tough and hard foods-complicating dietary inferences of early hominins. We posit that tapirs, large herbivorous mammals showing variable sagittal crest development across species, are ideal models for examining correlations between textural properties of food and sagittal crest morphology. Here, we integrate dietary data, dental microwear texture analysis, and finite element analysis to clarify the functional significance of the sagittal crest in tapirs. Most notably, pronounced sagittal crests are negatively correlated with hard-object feeding in extant, and several extinct, tapirs and can actually increase stress and strain energy. Collectively, these data suggest that musculature associated with pronounced sagittal crests-and accompanied increases in muscle volume-assists with the processing of tough food items in tapirs and may yield similar benefits in other mammals including early hominins.
古生物学家和古人类学家长期以来一直在广泛的生物多样性中争论颅形态和饮食之间的关系。虽然食肉动物中较大的颞肌附着区域（通过矢状嵴的存在）与硬食（即硬食）有关，但许多具有相似形态的灵长类动物食用各种坚韧和坚硬的食物，使对早期人类的饮食推断变得复杂。我们假设貘，一种大型草食性哺乳动物，在物种间具有可变的矢状嵴发育，是研究食物质地与矢状嵴形态之间相关性的理想模型。在这里，我们整合了饮食数据、牙齿微磨损纹理分析和有限元分析，以阐明貘的矢状嵴的功能意义。最值得注意的是，现存的和几种已灭绝的貘中，明显的矢状嵴与硬食之间呈负相关，实际上会增加压力和应变能。总的来说，这些数据表明，与明显的矢状嵴相关的肌肉组织——伴随着肌肉体积的增加——有助于貘处理坚韧的食物，并且可能在包括早期人类在内的其他哺乳动物中产生类似的益处。
