What animal did Lewis and Clark newly discover during their 1804 expedition up Old Baldy in Nebraska?
Black-tailed prairie dog The black-tailed prairie dog ("Cynomys ludovicianus"), is a rodent of the family Sciuridae found in the Great Plains of North America from about the United States-Canada border to the USA-Mexico border. Unlike some other prairie dogs, these animals do not truly hibernate. The black-tailed prairie dog can be seen above ground in midwinter. A black-tailed prairie dog town in Texas was reported to cover 64000 km2 and included 400,000,000 individuals. Prior to habitat destruction, this species may have been the most abundant prairie dog in central North America. This species was one of two described by the Lewis and Clark Expedition in the journals and diaries of their expedition.
Great hopping mouse The great hopping mouse ("Notomys robustus") is extinct. It is known only from skulls found in owl pellets in the Flinders Ranges. Some pellets also include bones of the introduced house mouse—indicating that it survived into historic times, possibly the second half of the 19th century. From the skull, it appears to have been relatively large (perhaps the size of "N. amplus" or a little more) and to have escaped collection by early 19th century naturalists by chance. From the location of the deposits it is assumed that it preferred clay rather than sandy soils. It is notable that very few of the clay-living hopping mice have survived European settlement, sand dunes apparently providing a more secure refuge from competitors and predators. It is also commonly known as the broad-cheeked hopping mouse.