Osborn, Henry Fairfield, 1857-1935.Gregory, William K. (William King), 1876-2005-10-062005-10-061916http://hdl.handle.net/2246/1331p. 721-723 : ill. ; 24 cm.234996 bytesapplication/pdfen-USQH1 .A4 vol.35, art.40, 1916Allops walcotti.Megacerops riggsi.Perissodactyla, Fossil -- South Dakota.Perissodactyla, Fossil -- Colorado.Mammals, Fossil -- South Dakota.Mammals, Fossil -- Colorado.Paleontology -- Oligocene -- South Dakota.Paleontology -- Oligocene -- Colorado.Paleontology -- South Dakota.Paleontology -- Colorado.text