Dietary and body mass reconstruction of the Miocene neotropical bat Notonycteris magdalenensis (Phyllostomidae) from La Venta, Colombia

With 14 species recorded, the Miocene La Venta bat fauna is the most
diverse bat palaeocommunity in South America. They include the oldest
plant-visiting bat in the New World, and some of the earliest
representatives of the extant families Phyllostomidae, Thyropteridae and
Noctilionidae. La Venta’s Notonycteris magdalenensis is an extinct member
of the subfamily Phyllostominae, a group of modern Neotropical
animalivorous bats, and is commonly included in studies of the evolution
of Neotropical bats, but aspects of its biology remain unclear. In this
study, we used multivariate dental topography analysis (DTA) to
reconstruct the diet of N. magdalenensis by quantitatively comparing
measures of molar complexity with that of 25 modern noctilionoid species
representing all major dietary habits in bats. We found clear differences
in molar complexity between dietary guilds, indicating that DTA is
potentially an informative tool to study bat ecomorphology. Our results
suggest N. magdalenensis was probably an omnivore or insectivore, rather
than a carnivore like its modern relatives Chrotopterus auritus and
Vampryum spectrum. Also, we reconstructed the body mass of N.
magdalenensis to be ~95 g, larger than most insectivorous bats, but
smaller than the largest carnivorous bat (V. spectrum). Our results
confirm that N. magdalenensis was not a specialised carnivore. It remains
to be demonstrated that the specialised carnivory ecological niche was
occupied by the same lineage of phyllostomines from at least the middle
Miocene. Combining our diet and body mass reconstructions, we suggest that
N. magdalenensis exhibits morphological pre-adaptations crucial for the
evolution of specialised carnivory.