Ontogenetic variability in the limb bones histology of plains vizcacha (Lagostomus maximus, Chinchillidae, Rodentia): implications for life history reconstruction of fossil representatives

Abstract

Osteohistological studies provide information on the life history of extant and extinct vertebrates, such as growth dynamics, age, body size, sexual maturity, sexual dimorphism, soft tissues, among others aspects. In this work, we evaluate the histological changes occurred during the ontogeny of extant representatives of plains vizcacha, Lagostomus maximus, through the analysis of limb bones in order to evaluate biological and ecological features of their life history. The results obtained are used as framework for the recognition of ontogenetic stages in isolated fossil limb bones of this species. The osteohistology clearly vary according to the ontogenetic stage of the individuals. It is described, for the first time, the presence of a neonatal line in rodents. We could identify different microstructural features that favor the correlation among extant and fossil representatives of L. maximus. It is considered that the mid-shaft of the humeri, femora and tibiae does not represent the most propitious sector to make the thin sections, since the modeling process there has erased part of the bone growth history of the individuals. This study contributes to the general knowledge of the bone histology of rodents.