Ontogenetic change in skull morphology and Mechanical Advantage in the Spotted Hyena (Crocutacrocuta) - Essay Example

Adult spotted hyena have durophagy adaptations that include large jaw, adductor muscles, simplified and robust dentition, and pronounced sagittal crest. Feeding of weaning hyena was limited by morphology compared to adult resulting from the study of ontogenetic change in the skull and feed apparatus. The study is, therefore, aimed at establishing as whether feeding of young hyena was limited by the skull shape, skull size, and the mechanical advantage of jaw muscles. The study also seeks to enquire if feeding apparatus is slow in the spotted hyena compared with other carnivores not adapted for durophagy.

Various materials and methods were employed during the study. For instant, during sampling, ontogenic series of individuals of age ranging from 2 months to 18 years of 68 spotted hyenas we sampled. Most of the samples were from the southwest of Kenya in Masai Mara Reserve. Their age was estimated depending upon the appearance. On the other hand, to quantify skull changes, ‘2D landmark-based geometric morphometrics was used. Three views of the skull were analyzed that involved lateral cranium, lateral mandibles, and ventral cranium.

In the analysis of fused lateral mandible and cranium for adult hyenas, semi-landmarks were used which later digitized by use of ‘tpsDig’. In addition, superimposition was used to remove variations (Holekamp, Lundrigan, Tanner and Zelditch 354). The analysis of change in ontogenetic shape was done as well as analyzing the relationship between shape and size over a given period (Holekamp, Lundrigan, Tanner and Zelditch 355). The ontogenetic trajectories were determined if they differed significantly.

As a result, the sample sizes obtained from a pair of bootstrap used varied with ages. On the other hand, size of the muscle and mechanical advantage was determined first using traditional methods. For instant, size of the adductor muscle was estimated across the zygomatic arches by maximum width. The mechanical advantage was