Jaw shape and mechanical advantage are indicative of diet in Mesozoic mammals

Jaw morphology is closely linked to both diet and biomechanical performance, and jaws are one of the most common Mesozoic mammal fossil elements. Knowledge of the dietary and functional diversity of early mammals informs on the ecological structure of palaeocommunities throughout the longest era of mammalian evolution: the Mesozoic. Here, we analyse how jaw shape and mechanical advantage of the masseter (MAM) and temporalis (MAT) muscles relate to diet in 70 extant and 45 extinct mammals spanning the Late Triassic-Late Cretaceous. In extant mammals, jaw shape discriminates well between dietary groups: insectivores have long jaws, carnivores intermediate to short jaws, and herbivores have short jaws. Insectivores have low MAM and MAT, carnivores have low MAM and high MAT, and herbivores have high MAM and MAT. These traits are also informative of diet among Mesozoic mammals (based on previous independent determinations of diet) and set the basis for future ecomorphological studies. Nuria Melisa Morales-Garcia et al. analyze jaw shape and mechanical advantage of 70 small modern mammals and 45 Mesozoic mammals and find that these metrics can be used to distinguish dietary groups for most extant mammals, and to infer diet in Mesozoic taxa.

Automated summary

In the study by Nuria Melisa Morales-Garcia et al., jaw shape and mechanical advantage of the masseter (MAM) and temporalis (MAT) muscles were analyzed in 70 extant and 45 extinct mammals. The researchers found that these metrics can accurately distinguish dietary groups in most extant mammals and can also be used to infer diet in Mesozoic taxa. This study lays the foundation for future ecomorphological studies in this field.