Snout shape and masticatory apparatus of the rodent-like mesotheriid ungulates (Typotheria, Notoungulata): Exploring evolutionary trends in dietary strategies through ancestral reconstructions

Mesotheriidae includes small to medium-sized herbivores that belong to the so-called South American native ungulates. Mesotheriids radiated from the early Oligocene to the early–middle Pleistocene and were traditionally grouped into two subfamilies: Trachytheriinae and Mesotheriinae. Beyond the conspicuous fossil record of the group, little is known about its palaeobiology and, particularly, the dietary habits. So far, different studies suggest grazing habits, similar to extant ungulates, but recent contributions are challenging this vision to some degree. In this contribution, we explore dietary preferences in mesotheriids, focusing on food intake and oral processing strategies. We performed a shape analysis of the snout and reconstructed ancestral shapes to assess evolutionary trends within the clade. Also, we considered other morphological variables linked to the masticatory apparatus (zygomatic plate, incisive foramina, cheek teeth morphology) to perform a functional characterizatio...