You may have seen some of them at the Denver Museum of Nature and Science, or maybe at the Smithsonian, but only in Wray, on the southern edge of the Sand Hills near the Nebraska border, can you see where these 10,000-year-old bison bones came from. They were originally unearthed in 1972 when a local rancher was digging an irrigation ditch; the Smithsonian later excavated the site, which yielded more than 41,000 bones, 248 stone artifacts and thousands of remains of smaller animals. As thanks for the town's contribution to adding to this treasure trove of science, the museum set up a permanent exhibit in Wray, complete with a few precious bison bones.