This is a 241,000-year-old fossil bat skull from Eddy County, New Mexico, called Constantine's free-tailed bat or Tadaria constantinei. With permission from the National Park Service, paleontologists from the New Mexico Museum of Natural History and Science, have collected hundreds of these skulls from guano deposits in Carlsbad National Park. The skull is extremely small and light, with huge auditory bulla (bone cavities) to help it hear its high frequency signals. This bat is a larger, extinct relative of the Mexican free-tailed bat, Tadaria brasiliensis, the most common modern inhabitant of Carlsbad Caverns.

Bats are very sensitive to cold, so this fossil bat must not have lived during an ice age. Instead, it comes from a time called "interglacial," similar to today's interglacial climate.