Diverse Early Pleistocene ground squirrels from northeastern Nebraska including a new genus and species

Abstract Ground squirrels (Rodentia, Sciuridae, Xerinae, Marmotini) diversified on the central Great Plains of North America during the Pliocene and Early Pleistocene, likely associated with the emplacement of modern-type grasslands. This diversity of Pliocene–Early Pleistocene ground squirrels is well documented from southwestern Kansas but is not well understood farther north and east on the Great Plains, a region that was periodically glaciated during the Early Pleistocene. Here, I report a composite assemblage of at least 10 species of ground squirrels from three Early Pleistocene (late Blancan) faunas in northeastern Nebraska, with eight species co-occurring at Big Springs. These fossils document early regional occurrence of the crown clade within Marmota Blumenbach; late regional persistence of the giant ground squirrel, Paenemarmota barbouri (Hibbard and Schultz); the earliest record of Poliocitellus Howell; the earliest record of Urocitellus Obolenskij from the Great Plains; early appearance of a small prairie dog–like ground squirrel, likely ? Cynomys andersoni Goodwin, otherwise only known from the early to middle Pleistocene of Colorado; and the presence of a distinctive ground squirrel described herein as Nebraskocitellus voorhiesi new genus new species. Overall, these findings document high regional diversity of ground squirrels during the Early Pleistocene, indicate the transitional composition of Early Pleistocene assemblages, and suggest that “modernization” of the ground squirrel assemblage on the central Great Plains began earlier in the northeast than documented in southwestern Kansas. UUID: http://zoobank.org/8e35d11a-9ea6-4269-96e3-2be783de48a9