Bats are capable of powered flight and remain relatively unchanged from one of the earliest recorded bat fossils, which is more than 52 million years old. Many bats navigate using sound, or echolocation.
One of the oldest bat fossils is about 52.5 million years old and is identical in many ways to modern bats. However, a 2008 fossil discovery showed a bat species lacking echolocation but capable of flight, indicating that flight evolved before echolocation.
Bat and bird wings are analogous structures, meaning that they serve the same function but are structurally dissimilar. Rather, a bat's wing is physically similar to the forelimbs of many other mammals, including humans. Bat wings show modifications for flight such as long fingers to support wing membranes and a less-flexible wrist that provides more support during flight.
Many bats navigate using echolocation; they emit high-frequency sounds that bounce off objects and back to the bats, allowing the animals to determine what they are flying toward. Bat echolocation is extremely loud despite being beyond the range of human hearing. Many bats average sound levels of about 110 decibels with the loudest species at nearly 140 decibels, which are near and above, respectively, the level of auditory pain in humans.