The U.S. Department of Interior has designated Nebraska's Ashfall Fossil Beds as a national natural landmark, the first such landmark to be designated in almost two decades. The site, near the town of Neligh (see Nebraska map), is home to hundreds of skeletons of extinct rhinos, camels, three-toed horses, and other vertebrates that were killed and buried by ash from a huge volcanic eruption some 12 million years ago. It is the only place on Earth where large numbers of fossil mammals have been found as whole, three-dimensionally preserved skeletons. "Ashfall has tremendous value for science and education and great...