Eomyids: happy old age or premature death? Reconstructing the life history of Ligerimys (Eomyidae, Rodentia, Mammalia)

Abstract

Mortality curves of extinct rodents can be reconstructed by using relative wear calculated from the amount of dentine exposed. MicroCT scanning of molars of the extinct Eomyid genus Ligerimys shows that this Wear Index increases gradually with wear; this means that wear classes can serve as a proxy for age and can therefore be used to reconstruct mortality curves. We reconstructed mortality curves of three species of Ligerimys from the late early Miocene of Spain. These curves show a similar trend, with decreasing numbers of molars as the amount of wear in each class increases. The curves show remarkable similarities to those of the wood mouse Apodemus. This suggests that Ligerimys was, like Apodemus, at the fast end of the fast-slow continuum, in other words r-selected, though not as extreme as some other rodents.