Ontogenetic variation in skull shape of Thrichomys apereoides (Rodentia : Echimyidae)

The pattern of change in shape during postnatal development in skulls of pu nare (Thrichomys apereoides) skulls, was studied by geometric morphometric techniques. Skull shape observed in T. apereoides varied both with size and age, but variation in size explains most of the overall change in shape. D ifferences in shape observed among the eight age categories showed that mai n changes in shape occurred principally between the first and second age ca tegories. Among the other age classes, changes became less pronounced leadi ng to elongation of the snout and the mid-face and narrowing of the basicra nium. The change in global shape resulted in lateral compression of the sku ll. Despite the high level of integration observed, localized transformatio ns dominated the ontogenetic changes in shape indicating the presence of tw o large scale cranium components-the orofacial and the basicranial region. The ontogenetic pattern in this species seems to follow the same trends obs erved in the initial phases of development.