Evolution of bone-cracking adaptations in hyaenids (Mammalia, Carnivora)

The Hyaenidae are one of the most diverse groups of carnivores in terms of body size and craniodental morphology, and as such they represent an ideal case to study the correlation between dental, and skeletal anatomy, and behavioral ecology in mammals. However, a comprehensive analysis, based on extant and fossil forms, including both gross-morphological and microstructural characters, is lacking. In this work, some representatives of the Hyaenidae were examined, in order to document the diversity of the masticatory apparatus, including enamel microstructure, and to trace the evolution of bone-cracking adaptations within this group. Primitive hyaenids lack bone-cracking modifications as compared to the generalized carnivore morphotype, in agreement with their insectivorous-omnivorous diet. A key innovation in hyaenid evolution was the acquisition of an enamel dominated by zig-zag Hunter-Schreger bands in the Middle Miocene, marking the transition of the group to the bone-eating niche. The observed morphological changes in hyaenids suggest an increasing degree of specialization towards bone-consumption.