Tooth enamel structure of some Australian carnivorous marsupials

Abstract

The tooth enamel structure of several specialized marsupial carnivores belonging to the Polyprotodonta and Diprotodonta were studied using scanning electron microscopy and are described in detail for the first time. Within the Polyprotodonta Dasyurus shows a simple schmelzmuster with radial and aprismatic enamel only, whereas the highly specialized teeth of Sarcophilus and Thylacinus show more complex schmelzmuster consisting of several enamel types. Both differ from each other and from other marsupials. Sarcophilus combines radial enamel, tangential enamel and stripes, Thylacinus combines radial enamel, tangential enamel, irregular enamel and stripes in its enamel. In both species the schmelzmuster varies within the dentition. Thylacoleo carnifex is the only carnivorous species within the dominatly herbivorous group Diprotodonta. It has distinct canine-like incisors and bladelike premolars that show a very complex enamel structure consisting of radial, tangential, irregular and zipper enamel and simultaneous prism deviations. Some of these enamel types are restricted to diprotodont marsupials and others are frequent in marsupials and placentals. The combination of enamel types in Thylacoleo differs from other studied marsupial carnivores. However, similar, but less complex schmelzmuster are present in other diprotodontids. In their combination of enamel types Sarcophilus, Thylacinus and Thylacoleo are unique. The high level of stuctural complexity within the specialized teeth of carnivorous marsupials indicates an adaptation to different loading conditions within and between teeth.