A cranial morphometric study of deer (Mammalia, Cervidae) from Argentina using three-dimensional landmarks

Abstract

This study examines morphological variation in the crania (n = 70) of eight cervid species from Argentina. Forty 3-dimensional landmarks were acquired on each adult cervid cranium. The data were analysed using Morphologika software. The co-ordinates were registered and scaled to remove size differences by Procrustes analysis, and then principal components analysis was applied to examine shape variation. Shape variation associated with each principal component can be visualised in the program. The first principal component correlates strongly with the centroid size of the crania and also with the body mass and height of each species. The larger species were distinguished by relatively longer snouts and relatively smaller brains. The smaller Mazama and Pudu species cluster closely on the first as well as the other principal components. Among the larger species, the two Hippocamelus species, which live at higher altitudes, were clearly distinguished from the lowland species, Ozotoceros bezoarticus and Blastocerus dichotomus, on the basis of cranial flexion and the orientation of the occipital region. Finally O. bezoarticus and B. dichotomus were compared directly and small differences were noted in the orbital region. The shape data was used to produce a distance matrix and a phenogram, which we relate to some of currently accepted phylogenetic relationships of this group of cervids.