Molossidae – Free-tailed bat
This family includes the fastest mammal on earth, the Mexican free-tailed bat that can fly at speeds of 159 km/h (99 mph)
Free-tailed bats are named due to their long thick tails, and they also have the name Mastiff bats because of the skin folds on their snouts, like that of the bullmastiff dog breed. They have long, narrow wings and short velvety fur (except for the naked bats, which are hairless).
They are not only fast fliers but are excellent climbers due to their strong legs. Free-tailed bats can also crawl backward using their unique tails to ‘feel out’ their path. Most live in colonies of thousands; the Mexican free-tailed bat holds another record as the largest mammalian social group, forming colonies of tens of millions of bats.