Hemphillian (Late Miocene) Snakes from Nebraska, with Comments on Arikareean Through Blancan Snakes of Midcontinental North America

Middle and late Hemphillian (late Miocene) snakes from Nebraska were identified and interpreted. The mid-Hemphillian (ca. 7 Ma) Lemoyne Quarry of Keith Co., SW Nebraska yielded at least two boid, thirteen colubrid and two viperid snakes. The late Hemphillian (ca. 5 Ma) Devils Nest (Knox Co.), Santee (Knox Co.), and Mailbox Prospect (Antelope Co.) sites of NE Nebraska together yielded at least nine colubrids and one viperid snake. Twenty-four percent of the 16 mid-Hemphillian snake genera and 67% of the 12 species are extinct. Of the 9 genera and 7 species of late Hemphillian snakes, only Paleoheterodon tiheni is extinct. A snake from Lemoyne Quarry is described as new (Arizona voorhiesi). With this new information, the fossil record of Arikareean through Blancan (Miocene through Pliocene) snake genera from midcontinental North America suggests erycinine boids became extinct across the region by late Hemphillian time, and colubrid snakes became generically modern by early Blancan time. These event...