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.颅骨的形态与功能之间的关联一直是众多研究的核心议题，其中多数研究聚焦于取食行为对颅骨形态的影响。然而，尚有诸多其他行为可对颅齿形态（craniodental morphology）产生影响。既往研究表明，以门齿进行掘土的地下啮齿类（凿齿挖掘型啮齿类，chisel-tooth digging rodents）的颅骨形态存在约束，这一现象可能源于其需要在大张口状态下产生高咬合力。与其他啮齿类相比，凿齿挖掘型啮齿类的上门齿牙根更向颅腔内后移。本研究对系统发育多样的啮齿类样本进行了颅骨形态与上门齿特征的量化分析，以探究凿齿挖掘型啮齿类的颅齿形态是否存在差异。研究结果显示，凿齿挖掘型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）使得这一类群的显著性检验未获支持。此外，研究发现凿齿挖掘型啮齿类的上门齿曲率显著大于其他啮齿类。值得注意的是，样本中的多数地下啮齿类（包括凿齿挖掘型与刨掘型地下啮齿类，scratch diggers），其上门齿的抗弯曲能力均优于陆生啮齿类，这一现象推测与其取食坚韧植物材料的食性相关。最终，本研究未发现该样本中上门齿特征与颅骨形态存在稳定的协同演化关系，这凸显了物种演化历史与功能形态之间的复杂关联。