Laboratorio de Morfología Funcional y Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMdP)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mar del Plata, Argentina.
División Mecánica de Materiales, Instituto de Investigaciones en Ciencia y Tecnolgía de Materiales (INTEMA), Universidad Nacional de Mar del Plata (UNMdP)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mar del Plata, Argentina.
J Anat. 2019 Apr;234(4):564-575. doi: 10.1111/joa.12946. Epub 2019 Feb 15.
The monophyletic group Caviomorpha constitutes the most diverse rodent clade in terms of locomotion, ecology and diet. Caviomorph species show considerable variation in cranio-mandibular morphology that has been linked to the differences in toughness of dietary items and other behaviors, such as chisel-tooth digging. This work assesses the structural strength of the mandible of three caviomorph species that show remarkable differences in ecology, behavior and bite force: Chinchilla lanigera (a surface-dwelling species), Octodon degus (a semi-fossorial species) and Ctenomys talarum (a subterranean species). Finite element (FE) models of the mandibles are used to predict the stresses they withstand during incisor biting; the results are related to in vivo bite forces and interspecific variations in the mandibular geometries. The study concludes that the mandible of C. talarum is better able to withstand strong incisor bites. Its powerful adducting musculature is consistent with the notorious lateral expansion of the angular process and the masseteric crest, and the enhanced cortical bone thickness. Although it has a relatively low bite force, the mandible of O. degus also shows a good performance for mid-to-strong incisor biting, in contrast to that of C. lanigera, which exhibits, from a mechanical point of view, the worst performance. The mandibles of C. talarum and O. degus appear to be better suited to withstand stronger reaction forces from incisor biting, which is consistent with their closer phylogenetic affinity and shared digging behaviors. The contrast between the low in vivo bite force of C. lanigera and the relatively high estimations that result from the models suggests that its adductor musculature could play significant roles in functions other than incisor biting.
单系类群栉鼠形亚目在运动、生态和饮食方面构成了最多样化的啮齿动物分支。栉鼠形目物种的颅颌形态有很大的变化，与饮食项目的韧性差异以及其他行为（如凿齿挖掘）有关。这项工作评估了三种生态、行为和咬合力差异显著的栉鼠形目物种的下颌结构强度：毛丝鼠（一种地表物种）、豚鼠（一种半掘穴物种）和白足鼠（一种地下物种）。下颌的有限元（FE）模型用于预测在门齿咬合过程中它们承受的应力；结果与体内咬合力和下颌几何形状的种间变异有关。研究得出结论，白足鼠的下颌更能承受强烈的门齿咬伤。它强大的内收肌与角突和咬肌嵴的明显侧向扩张以及增强的皮质骨厚度一致。尽管咬合力相对较低，但豚鼠的下颌也能很好地承受中高强度的门齿咬伤，而毛丝鼠的表现则相对较差，从力学角度来看，它的表现最差。从机械角度来看，白足鼠和豚鼠的下颌似乎更适合承受更强的门齿咬伤反作用力，这与它们更接近的系统发育亲缘关系和共同的挖掘行为一致。毛丝鼠体内咬合力较低，但模型得出的相对较高的估计值表明，其内收肌在门齿咬伤以外的功能中可能发挥重要作用。
