New philisids (Mammalia, Chiroptera) from the Early–Middle Eocene of Algeria and Tunisia: new insight into the phylogeny, palaeobiogeography and palaeoecology of the Philisidae

Among the Afro-Arabian Palaeogene chiropterans, philisids were the most common and diversified members. The Philisidae are considered as an extinct primitive group of Vespertilionoidea, a well-diversified superfamily that today includes Natalidae, Molossidae and Vespertilionidae. However, the position of Philisidae within this superfamily has never been clearly established. These bats are characterized by a very distinctive dental morphology, and include some representatives that were among the largest bats to be known. Here we describe new dental remains attributable to philisids from the Early–Middle Eocene of Chambi, Tunisia and Gour Lazib area, Algeria. These fossils allow us to reconsider the dental morphology of the oldest philisids: Dizzya exsultans Sigé, 1991 and Witwatia sigei Ravel, 2012. We have undertaken a cladistic assessment of the dental evidence (47 dental and mandible characters) to clarify the phylogenetic relationships within Philisidae, and its position within Vespertilionoidea, in order to highlight the origin, historical biogeography and patterns of dispersion of the most diversified extant bat group. The specialized dental morphology of philisids implies particular occlusion seen in the three-dimensional reconstructions of teeth of Witwatia sigei and Dizzya exsultans. The peculiar morpho-functional anatomy of the teeth and the large size of these bats were well adapted to an opportunistic diet, and probably contributed to the early success of the family in North Africa.