UMR 7179, Mécanismes Adaptatifs et Evolution (MECADEV), Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Paris, France.
UMR 7205, Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d'Histoire naturelle, Sorbonne Université, Centre National de la Recherche Scientifique, Ecole Pratique des Hautes Etudes, Université des Antilles, Paris, France.
J Anat. 2021 Apr;238(4):886-904. doi: 10.1111/joa.13359. Epub 2020 Nov 18.
Limb long bones are essential to an animal's locomotion, and are thus expected to be heavily influenced by factors such as mass or habitat. Because they are often the only organs preserved in the fossil record, understanding their adaptive trends is key to reconstructing the paleobiology of fossil taxa. In this regard, the Bovidae has always been a prized group of study. This family is extremely diverse in terms of both mass and habitat, and it is expected that their bones will possess adaptations to both factors. Here, we present the first 3D geometric morphometric study focusing on bovid limb long bones. We used anatomical landmarks as well as curve and surface sliding semi-landmarks to accurately describe the stylopod and zeugopod bones. We included 50 species from ten of the twelve currently recognized tribes of bovids, ranging from 4.6 to 725 kg, and living in open plains, forests, mountains, or anywhere in-between. Shape data were correlated with the mean mass of the species and its habitat, even when taking into account the phylogenetic history of our sample. Bones pertaining to heavy species are more robust, adapted for a better repartition of stronger forces. Articulations are especially affected, being proportionally much larger in heavier species. Muscle insertion areas are unevenly affected. Insertion areas of muscles implied in body support and propulsion show a strong increase in their robustness when compared to insertion areas of muscles acting on the limb mostly when it is off the ground. Habitat influences the shape of the humerus, the radius-ulna, and the femur, but not of the tibia, whether the phylogeny is taken into account or not. Specific habitats tend to be associated with particular features on the bones. Articulations are proportionally wider in open-habitat species, and the insertion areas of muscles involved in limb extension and propulsion are wider, reflecting the fact that open habitat species are more cursorial and rely on fast running to avoid predators. Forest and mountain species generally present similar adaptations for increased manoeuvrability, such as a round femoral head, and generally have more gracile bones.
四肢长骨对于动物的运动至关重要，因此预计它们会受到体重或栖息地等因素的强烈影响。由于它们通常是化石记录中唯一保存下来的器官，因此了解它们的适应趋势是重建化石分类群古生物学的关键。在这方面，牛科一直是一个备受关注的研究群体。该科在体重和栖息地方面都具有极高的多样性，预计它们的骨骼将适应这两个因素。在这里，我们首次进行了一项专注于牛科四肢长骨的 3D 几何形态测量学研究。我们使用解剖学标志以及曲线和曲面滑动半标志来准确描述腕骨和跗骨。我们包括了来自目前公认的牛科 12 个部落中的 10 个部落的 50 个物种，体重从 4.6 公斤到 725 公斤不等，生活在开阔平原、森林、山脉或介于两者之间的任何地方。即使考虑到我们样本的系统发育历史，形态数据也与物种的平均体重及其栖息地相关。体重较大的物种的骨骼更粗壮，更适合更好地分配更强的力量。关节尤其受到影响，在较重的物种中比例更大。肌肉附着区受到不均匀的影响。用于支撑和推进身体的肌肉的附着区与主要在离开地面时作用于肢体的肌肉的附着区相比，其粗壮程度有很强的增加。无论是否考虑到系统发育，栖息地都会影响肱骨、桡骨-尺骨和股骨的形状，但不会影响胫骨的形状。特定的栖息地往往与骨骼上的特定特征相关。开阔栖息地的物种的关节比例更宽，参与肢体伸展和推进的肌肉的附着区更宽，这反映了开阔栖息地的物种更具奔跑能力，依靠快速奔跑来躲避捕食者的事实。森林和山地物种通常具有相似的适应能力，以提高机动性，例如圆形股骨头，并且通常具有更纤细的骨骼。
