Ursavus is an extinct genus of bear that existed in North America, Europe, and Asia during the Miocene period, about 23–5.3 million years ago (Mya), existing for roughly 17.7 million years.[2][3] The genus apparently dispersed from Asia into North America about 20 Mya, becoming the earliest member of the subfamily Ursinae in the New World.[4] Qiu points out that if a questionable 29 million-year-old specimen of Ursavus reported in North America is validated, Ursavus may have evolved in North America and dispersed westward into Asia. The higher number of fossils in Europe grading toward eastern Asia make the westward dispersal unlikely.
U. elmensis, also known as the "dawn bear"[5] is generally taken to be the earliest undisputed bear species.[6][7]
^Qiu, Zhan-Xiang; et al. (2014). "A Late Miocene Ursavus skull from Guanghe, Gansu, China". Vertebrata PalAsiatica. 52 (3): 265–302.
^Kurten, Bjorn (1966). "Pleistocene bears of North America I: Genus Tremarctos, spectacled bears". Acta Zool. Fenn. 115: 1–120.
^Crusafont, M.; Kurten, B. (1976). "Bears and bear-dogs from the Vallesian of the Valles-Penedes basin, Spain". Acta Zool. Fenn. 144: 1–29.
^Derocher, Andrew E.; Ian Stirling (February 1989). "Factors affecting the evolution and behavioral ecology of the modern bears". Bears: Their Biology and Management. A selection of papers from the Eighth International Conference on Bear Research and Management. 8 (published 1990): 189–204. doi:10.2307/3872919. JSTOR3872919.
^McLellan, Bruce (1994). "A review of bear evolution"(PDF). [Proceedings of the] International Conference on Bear Research and Management. 9 (1): 85–96.
^Derocher, A. E.; Lynch, W. (2012). Polar Bears: A complete guide to their biology and behavior. Baltimore: Johns Hopkins University Press.