The Norden Bridge Quarry in the Mio- Pliocene Valentine Formation of Brown County, Nebraska [USA], has produced a rodent fauna of 14 species in 8 families. Most species belong to genera previously known from the North American Late Miocene and Early Pliocene; however, Plesiosminthus and Allomys were previously known only from the Early Miocene, and Leptodontomys from the Middle Pliocene. One species (Allomys stirtoni) is described as new. The Norden Bridge rodent fauna is much richer than other known local faunas in the Valentine Formation, but seems to be similar to the next best known one.