Structure of the upper teeth of the red fox (Vulpes vulpes) and Arctic fox (Vulpes lagopus) and analysis of dental variability in insular forms

Various polymorphic dental characters of Vulpes vulpes and Vulpes lagopus have been described on the basis of a detailed description of the occlusal surfaces of P4, M1, and M2. The prevalence of these characters was found to be significantly different between samples of V. vulpes and mainland V. lagopus, which can be used to determine species in a fossil record. Notably, Commander Islands V. lagopus differ from mainland V. lagopus in most of the characters. However, some characters of Mednyi Island V. lagopus are unique to them and are not found in any other sample. Some samples from Bering Island do not display such specific features. Samples of ancient foxes, V. praeglacialis and V. praecorsac, have also been studied. Primitive features were observed in both V. praeglacialis and V. praecorsac, with the latter exhibiting also a number of advanced features. It has also been found that primitive features are prevalent in the maxillary dentition of V. vulpes. The insular groups of V. lagopus display numerous primitive features, whereas mainland V. lagopus demonstrate a substantial number of advanced characters. This combination of primitive and advanced features is typical of insular V. lagopus and indirectly suggests that these populations have spent a long time in isolation.