Romaniuk H. Morphofunctional features of the masticatory apparatus of Palearctic mustelids (Mustelidae, Carnivora)

The thesis is a complex study of the jaw apparatus of Palearctic mustelids (Mustelidae) in connection with their trophic specializations. 290 specimens of 14 extant mustelid species (genus Enhydra, Gulo, Meles, Lutra, Martes, Mustela) were analyzed. Standard morphometric methods (43 cranial, mandible and teeth measurements were used), geometric morphometrics (a set of 16 two-dimensional mandibular landmarks was used) and biomechanical approaches (strength indicators such as section moduli, strength and critical bite force of the mandibles and teeth were calculated) were used. The parameters of the cheek teeth have the greatest influence on the differences between specimens of mustelids. Within Mustelidae, the same patterns are observed as within Carnivora: the hypercarnivorous (Mustela) are close to felids, and the omnivorous (Martes) are close to canids. Carnivorous mustelids have strengthened mandibles, especially at the front edge, large carnassials, increased slicing area of m1, omnivorous have thinner and longer mandibles, and the durophagous mustelids, which feed on tough objects, have thicken mandibles under the molars. In Enhydra lutris and Meles meles, the crushing area of the molar complex is enlarged. Piscivorous Lutra lutra is intermediate among other trophic groups in all the features of jaw apparatus. Two types of the ascending ramus mandibulae are observed in mustelids. Both types are present both in closely related species and in species with similar trophic specialization. Short mandibles have mechanical advantages not only for the masticatory muscles, but also due to the reduced bending moment, which increases the strength of the mandibular corpus. Subdivision of mandible into two modules (into the alveolar region and the ascending ramus) with masseteric fossa included in corpus is most possible.