Fractal dimension and suture complexity in Odocoileus virginianus (Cervidae, Odocoileini) and the relationships with age and antler size

CASSINI, GUILLERMO HERNÁN; DOYLE, SANTIAGO RAUL; MERINO, MARIANO LISANDRO

Punta del Este -Uruguay

Congreso; 9th International Congress of Vertebrate Morphology; 2010

Universidad de La República - International Society of Vetebrate Morphologyst

Cranial biomechanics has been frequently associated to the torsion and stress forces that occur during mastication in carnivorous and herbivorous mammals. However, the predominant herbivores used in these studies, bovids and cervids, have horns and antlers that can be quite big and used in intraspecific fighting during reproductive seasons. From a biomechanical point of view, fight and antlers weight could generate torsion and stress loads in the cranial vault that may cause lesions or deformation. To assess the influence of these structures on cranial biomechanic, cervids can be use as a case study, due to their sexual dimorphism and increase of antlers’ complexity and size during ontogenetic growth. In this contribution we analyze in a postnatal ontogenetic series of Odocoileus virginianus the complexity of interfrontalis and coronalis sutures using fractal dimension (FD), and their correlation with the total length of skull and the length of principal branch of antlers, to assert differences due to sexual dimorphism and age (and related to this the antler size). FD was obtained by means of image analysis with two differents methods: box-counting and Minkowski Sausage method. Results obtained by both methods are coherent, indicating that juveniles have low values of FD, similar to a Euclidean curve, and FD increases during ontogenetic growth. ANCOVA shows that males have greater FD than females of similar size. Among males, FD increases with antlers’ size. These results suggest that suture complexity is correlated with antlers (presence and size).