Alt. Name: Aardwolf
Location: Comparative collection of Z.J. Tseng
Specimen ID: J050607T02
This is a stl file of the cranium of an aardwolf. Aardwolves are myrmecophagous (ant-eating) hyenas found today in eastern and southern Africa. Known to be the most basal (primitive) member among the four living hyaenids, aardwolves remain enigmatic in their evolutionary origins, with incongruent evidence from molecular and morphological studies. The anatomical data were obtained using CT scanning; the complete CT dataset is available through the publication associated with this model.
Title: Testing Adaptive Hypotheses of Convergence with Functional Landscapes: A Case Study of Bone-Cracking Hypercarnivores
Authors: Tseng, Z.J.
Journal: PLOS ONE 8(5): e65305
Morphological convergence is a well documented phenomenon in mammals, and adaptive explanations are commonly employed to infer similar functions for convergent characteristics. I present a study that adopts aspects of theoretical morphology and engineering optimization to test hypotheses about adaptive convergent evolution. Bone-cracking ecomorphologies in Carnivora were used as a case study. Previous research has shown that skull deepening and widening are major evolutionary patterns in convergent bone-cracking canids and hyaenids. A simple two-dimensional design space, with skull width-to-length and depth-to-length ratios as variables, was used to examine optimized shapes for two functional properties: mechanical advantage (MA) and strain energy (SE). Functionality of theoretical skull shapes was studied using finite element analysis (FEA) and visualized as functional landscapes. The distribution of actual skull shapes in the landscape showed a convergent trend of plesiomorphically low-MA and moderate-SE skulls evolving towards higher-MA and moderate-SE skulls; this is corroborated by FEA of 13 actual specimens. Nevertheless, regions exist in the landscape where high-MA and lower-SE shapes are not represented by existing species; their vacancy is observed even at higher taxonomic levels. Results highlight the interaction of biomechanical and non-biomechanical factors in constraining general skull dimensions to localized functional optima through evolution.