In an image provided by the Bureau of Land Managementc, cave specialist Bryan McKenzie rappels into Natural Trap Cave in north-central Wyoming during a cleanup expedition. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Starting July 28, 2014, scientists plan to venture back into the cave and resume digging for the first time in more than 30 years.The Associated Press