Data from: The impact of digging on craniodental morphology and integration

The relationship between the form and function of the skull has been the subject of a great deal of research, much of which has concentrated on the impact of feeding on skull shape. However, there are a number of other behaviours that can influence craniodental morphology. Previous work has shown that subterranean rodents that use their incisors to dig (chisel-tooth digging) have a constrained cranial shape which is probably driven by a necessity to create high bite forces at wide gapes. Chisel-tooth digging rodents also have an upper incisor root that is displaced further back into the cranium compared with other rodents. This study quantified cranial shape and upper incisors of a phylogenetically diverse sample of rodents to determine if chisel-tooth digging rodents differ in craniodental morphology. The study showed that the crania of chisel-tooth digging rodents shared a similar place in morphospace, but a strong phylogenetic signal within the sample meant that this grouping was non-significant. It was also found that the curvature of the upper incisor in chisel-tooth diggers was significantly larger than in other rodents. Interestingly, most subterranean rodents in the sample (both chisel-tooth and scratch diggers) had upper incisors that were better able to resist bending than those of terrestrial rodents, presumably due to their similar diets of tough plant materials. Finally, the incisor variables and cranial shape were not found to covary consistently in this sample, highlighting the complex relationship between a species’ evolutionary history and functional morphology.颅骨形态与功能的关联始终是诸多研究关注的核心议题，其中绝大多数研究聚焦于取食行为对颅骨形状的影响。然而，尚有诸多其他行为可对颅牙形态学（craniodental morphology）产生影响。既往研究表明，依靠门齿掘土的地下啮齿类（subterranean rodents）——即凿齿掘土类（chisel-tooth digging）啮齿类——其颅骨形状受到约束，这一现象可能源于其需要在大张口度下产生高咬合力。与其他啮齿类相比，凿齿掘土类啮齿类的上门齿牙根更向颅骨后方移位。本研究针对一组系统发育多样的啮齿类样本，对其颅骨形状与上门齿特征开展量化分析，以探究凿齿掘土类啮齿类在颅牙形态学上是否存在显著差异。研究结果显示，凿齿掘土类啮齿类的颅骨在形态空间（morphospace）中占据相似的位置，但样本内较强的系统发育信号（phylogenetic signal）使得该类群的分组未达统计学显著性水平。此外，研究还发现凿齿掘土类啮齿类的上门齿曲率显著高于其他啮齿类。值得注意的是，样本中的多数地下啮齿类（涵盖凿齿掘土类与刨掘类（scratch diggers）），其上门齿的抗弯曲性能均优于陆生啮齿类，推测这一特征与其赖以摄食的坚硬植物性食物密切相关。最后，本研究未发现该样本中上门齿特征与颅骨形状存在稳定的协变关系，这凸显了物种进化历史与功能形态学之间的复杂关联。