question: What animal did Lewis and Clark newly discover during their 1804 expedition up Old Baldy in Nebraska?
answer: black-tailed prairie dog
context: Title: Lewis and Clark Pass (Montana)
  Passage: Lewis and Clark Pass, el.  6424 ft is a mountain pass on the continental divide in Montana.  It lies at the head of the drainages of the west flowing Blackfoot River and the east flowing Dearborn River.  The pass is in the Helena National Forest in Lewis and Clark County.  The Continental Divide Trail traverses north and south through the pass.  At the time of the Lewis and Clark Expedition the pass was a much-used pathway where the native people living in what today is Montana crossed over the continental divide.  The pass was crossed by Meriwether Lewis on July 7, 1806, on the return leg of the Lewis and Clark Expedition with a party of nine men and his dog Seaman.  The pass was named for the expedition's two leaders–Lewis and William Clark.  Lewis and Clark Pass is the only roadless pass on the entire Lewis and Clark National Historic Trail.  It has gone from being one of the most used continental divide passes prior to the pioneer era to one of the least visited passes today.  It can be accessed by a 1.5 mi trail.  Visitors will encounter the pass much as Lewis did in 1806.  The furrows left by the countless dog and horse travois that crossed the pass are still visible (though fading) and this is one of the places along the expedition's route that visitors may still encounter a grizzly bear.  On a clear day, like Meriwether Lewis in 1806 one can see Square Butte in Cascade County, Montana, 40 mi to the northeast.
  Title: Old Baldy Council
  Passage: The Old Baldy Council (#043) was founded in 1917 as the Pomona Council.  It changed its name in 1921 to Old Baldy.  The Old Baldy name is from Mount San Antonio, often called "Old Baldy" or "Mount Baldy", the highest peak in the San Gabriel Mountains.
  Title: Old Baldy (Lynch, Nebraska)
  Passage: Old Baldy, also known as the Tower, is a hill located near the village of Lynch, in Boyd County, in the northern part of the state of Nebraska in the Midwestern United States.  It was visited by the Lewis and Clark Expedition on their way up the Missouri River in 1804; nearby, they discovered a colony of prairie dogs, an animal previously unknown to scientists.
  Title: Black-tailed prairie dog
  Passage: 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.
citations: Old Baldy (Lynch, Nebraska) Black-tailed prairie dog