Brachylagus is currently a monotypic genus of uncertain origins and known only from Holocene and late Rancholabrean. A new species of leporid is described from the early and middle Pleistocene (Irvingtonian) deposits of Porcupine Cave, Park County, Colorado. Stratified deposits of the Pit and the Velvet Room, 2 localities within Porcupine Cave, have been dated biochronologically and paleomagnetically from the middle Irvingtonian and early to middle Irvingtonian, respectively. Brachylagus coloradoensis sp. nov., is characterized by its conserved p3 enamel patterns which are intermediate between B. idahoensis and Hypolagus, and its size which is slightly larger than that of B. idahoensis. This suggests a possible ancestral relationship between Hypolagus and Brachylagus.
Ramos, Colleen N.
"An Irvingtonian species of Brachylagus (Mammalia: Lagomorpha) from Porcupine Cave, Park County, Colorado,"
Great Basin Naturalist: Vol. 59
, Article 6.
Available at: http://scholarsarchive.byu.edu/gbn/vol59/iss2/6