Fifty million years ago, during the Geiseltalion Period, the Messel area was covered by a large series of lakes which were surrounded by lush sub-tropical forest that supported and incredibly diverse variety of life forms. The oil shale, present today, was created by the slow decomposition of dead vegetation in an anoxic environment combined with the fine grained sediments which accumulated at the bottom of these lakes. Because the plants and animals were deposited at the bottom of these lakes where there was little or no oxygen present, very little disturbance or scavenging would have taken place. This, along with the fine grained sediments, led to the excellent preservation of complete skeletons, including skin, fur, and feathers in some cases. Based on their comparative physiology to modern bats it has been determined that the bats found at Messel can be placed into three groups. The Hassianycteris species mastered high and fast flying over the tree-crowns. The Archaeonycteris species flew at moderate altitudes and speed. The Palaeochyropteryx was light and manuverable and flew slow and close to the ground and foliage. Close analysis of Messel bats indicates that they lacked adequate inner ear size for sophisticated echolocation using ultrasound which is generally found in present day bats. It is assumed that they used echolocation primarily for avoiding obstacles and used sight, smell, and sound for hunting. Dimensions: 4-3/8" x 5-7/8" x 5/8"