Influence of biotic and abiotic environment on dental size and shape evolution in a Late Miocene lineage of murine rodents (Teruel Basin, Spain)

Dental size and shape evolution in a Late Miocene lineage of murine rodents is analyzed, based on a set of deposits from the Teruel Basin (Spain). The lineage leads from Progonomys hispanicus, characterized by small and primitive molars, to Stephanomys ramblensis, characterized by large and specialized, stephanodont molars. A dietary change from granivory to herbivory is assumed to accompany this morphological change. Fourier analysis of molar outlines shows that size and shape evolve gradually with time. However, evolutionary rates of size and shape of upper and lower molars differ along the lineage. This suggests that mosaic evolution occurs with respect to upper and lower molars, and that size and shape are under different selective pressures. Comparison with biotic factors, i.e. diversity of the local community, and abiotic parameters, i.e. climatic reconstruction based on the rodent community and marine δ18O record, suggests that morphological evolution may be influenced by environmental variations. Climatic changes are suggested to influence biotic variations via opening of new ecological niches, favoring morphological evolution in murine rodents during the Late Miocene.