Early Pleistocene leporids (Mammalia, Lagomorpha) of Roland Springs Ranch Locality 1 and the rise of North American Quaternary leporines

The RSR-1 sample is considered against the backdrop of Neogene-Quaternary faunal turnover that included the extinction of the Archaeolaginae and radiation within the extant subfamily, Leporinae. Leporid abundance during the late Pliocene-early Pleistocene (Blancan Land Mammal Age) of North America marks peak species richness for the rabbit family. Late Miocene-early Pleistocene changes in climate and grassland composition and structure in North America coincide with this pivotal period of leporid natural history. Environmental shifts potentially created a period of expanded physical heterogeneity and niche diversification that provided the ecological conditions for archaeolagines, Blancan leporines, and emerging derived, modern type (Lepus pattern) leporines to widely coexist. The Lepus pattern of extant cottontails and jackrabbits, is hypothesized as a competitive advantage initiated by grassland change and particularly suited for the arid and open Quaternary Great Plains.