Megabat evolved early in the lineage of chiropterans. Although echolocation was later lost in family Pteropodidae, bats in the genus "Rousettus" are capable of primitive echolocation through clicking their tongues, and some species have been shown to create clicks similar to those of echolocating bats using their wings. Both echolocation and flight are energetically expensive processes. The nature of the flight and echolocation mechanism of bats allows for creation of echolocation pulses with minimal energy use. Energetic coupling of these two processes is thought to have allowed for both energetically expensive processes to evolve in bats. The loss of echolocation may
Large slit-faced bat fly over long distances. Although smaller bats are consumed by "N. grandis", they are only eaten when they fly into the roosts of "N. grandis". "N. grandis" produces low-intensity echolocation calls at high frequencies, which makes them nearly inaudible except at close range. Instead of relying on echolocation to find their prey, these bats listen for wing fluttering of smaller bats and even insects. However, as "N. grandis" gets closer to its prey during a hunt, it exudes a louder echolocation call. At the beginning of the pursuit, the call ranges from 17-114 kHZ, and rises to a range of