A QUANTITATIVE APPROACH TO THE CRANIAL ONTOGENY OF LYCALOPEX CULPAEUS (CARNIVORA: CANIDAE)

SEGURA, V.; PREVOSTI, F. J.

Congreso; 9º International Congress of Vertebrate Morphology; 2010

ICVM

The cranial ontogeny of specialized mammals is relevant to understand the connection of formand function in a developmental, ecological, and evolutionary context. Lycalopex culpaeus isthe largest fox in the genus and is considered more carnivorous and a consumer of largemammalian prey than other South American foxes. The transition from milk suckling to thedemanding feeding habits of adults must be accompanied by pronounced modifications inmorphology and behavior. We studied the postnatal ontogeny of the skull using a quantitativeapproach in an ontogenetic series of 101 skulls. They ranged from two months to 11 years old.We use linear measurements and geometric morphometrics. With both methods, we detect aclose interaction between neurocranium and splachnocranium, resulting in a modified adultskull, functionally adapted to a more carnivore feeding habits. The trends observed includepatterns as the negative allometry of the braincase and the positive allometry of the zygomaticbreadth, whose combination determine the space for the temporal musculature. The height ofthe mandibular ascendant ramus, implied in the insertion of the masseteric muscle, is relatedwith the mechanical resistance. Some features, like strong development of crests (sagittal andlambdoidal), and growth and strengthening of processes (postorbital and postglenoid), aredetected only with geometric morphometrics. Both methods indicate that the major ontogeneticchanges are directly linked to cranial structures that support a developing masticatory apparatusand its associated jaw and neck musculature, essential for the action of canines and carnassialsduring the killing bite and slicing flesh.