This family is represented globally by about 126 species in 22 genera, of which 20 species in seven genera have been recorded from southern Africa (Taylor et al. 2019c). Members of the Molossidae are immediately recognisable by the unique arrangement of the tail, which extends beyond the end of the tail membrane, giving rise to the common name of this group – free-tailed bats (Figure 196a). They have plain faces without noseleafs, but the upper lip is typically wrinkled in most molossids (except in the larger Tadarida species), giving them a bulldog appearance (Figure 196b). Pheromones are important in their social behaviour. Each species has a distinct, strong, often aromatic scent (Kingdon 1974). The family includes some of the commonest (Chaerephon pumilus), as well as rarest (Chaerephon gallagheri and Tadarida lobata) African bat species. Much of what we know about the more poorly known species reflects the devoted research of the late Randolph Peterson of the Royal Ontario Museum and the late David L. Harrison.

Some African molossids, notably Mops condylurus, are locally abundant, but a surprising number of species are among the rarest and most poorly known of mammals, a situation exemplified by Tadarida lobata and T. ventralis (Figures 195 and 241). Their inconspicuous roosts and high-flying habits make them challenging to locate and study. By their very nature, many locality records of molossids reflect serendipitous collecting events, which are so sparse that our knowledge of even the basic biology of most species has not improved since their original discoveries – even though several of these species were made known to science over 150 years ago. This is epitomised by the enigmatic circumstances in which two new species of forest-dwelling African molossids were discovered over a century ago:

Our knowledge of the biology of both M. congicus and C. russatus is still poor; it resides primarily in the museum records from Africa's equatorial forest belt.