On the Morphology and Ecology of the Fossil Don Hare (Lepus tanaiticus Gureev, 1964)

Abstract

Frozen mummies and their parts of the fossil Don hare are studied for the first time. They were found in permafrost deposits of the Upper Pleistocene in different regions of Yakutia: Verkhoyansky, Abyysky, and Nizhnekolymsky districts. Radiocarbon dating has shown that the studied hares lived in the second half of the Late Neopleistocene, 50.1–23.6 thousand years ago (the time of Karginian interstadial–Sartanian glaciation). A number of morphological adaptations of this extinct species to living conditions in the Arctic steppes of the Pleistocene of Yakutia have been identified: greater length and, apparently, body weight, short ears and feet, a strong locomotor apparatus of the hind limbs, hard hair brushes on the feet, and excellent heat-protective properties of the hair, including the specific microstructure of hairs. Comparison of the hairs of an adult individual and a month-old individual of Don hare has shown a polymorphism of the fur. The hairs are characterized by the presence of grooves, a columnar medulla, and a chevron cuticle, which allow an unmistakable identification of the taxon. In both individuals, specific hairs on the soles of the pads form a protective “cushion” that facilitates movement along snow, ice, and swamps. Based on palynological studies, understanding of the paleoecology of this species is expanded. Lepus tanaiticus lived in open landscapes: cold steppes dominated by xerophytic communities and grass–forb and sedge–forb meadows; unlike the modern mountain hare L. timidus, which generally feeds on shoots and bark of trees and shrubs in winter, the winter diet of Don hare included mainly herbaceous plants.