Abstract
Additional fossil material from the Valentine Formation in Knox and Brown Counties, Nebraska, has allowed for the recognition of three new species of rodents, a heteromyid (Perognathus brevidens), a geomyid (Parapliosaccomys annae), and a zapodid (Schaubeumys cartomylos). The specimens referred here toP. brevidenswere previously identified asP. furlongi, those ofS. cartomyloswere identified asS. grangeri, and those ofP. annaewere previously recognized asLignimuscf.L. hibbardi. It is evident thatLignimusStorer should be restricted to the type speciesL. montis, and the remainder of the species referred to this genus are referred toParapliosaccomysShotwell.Parapliosaccomysis recognized as the earliest member of the subfamily Geomyinae based on its dental morphology, which extends the range of this subfamily into the Barstovian. The fauna from Annie's Geese Cross Quarry (Knox County) is recognized as being late Barstovian based on comparison with the older Norden Bridge Quarry (Brown County).
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