A TREE SQUIRREL (RODENTIA, SCIURIDAE, SCIURINI) FROM THE LATE MIOCENE (CLARENDONIAN) OF NEVADA

摘要: ABSTRACT A new species of squirrel, Sciurus olsoni, from the late Miocene (Clarendonian) Nevada, is distinguished other by its smaller size and minor differences in cheek teeth. It first record extant genus Sciurus, a tree squirrel (tribe Sciurini) North America between early (Arikareean) Pleistocene. This occurrence suggests that history squirrels was probably continuous through Neogene, intermittent fossil due both to preservation bias their never having been abundant as living elements faunas; they are rare even where do occur deposits otherwise very richly fossiliferous. The later Tertiary Pleistocene radiation may have originated America.