The evolution of body size, horn shape and social behaviour in crown Antilopini - an ancestral character state analysis

The earliest known bovids, commonly placed in the genus Eotragus, are small species with short straight horns that are located above the orbits. Among living bovids there are several species that show a similar horn morphology. These dwarf antelopes were historically united in the group „Neotragini“, which is now known to be a polyphyletic assemblage. The species in the genera Ourebia, Raphicerus, Dorcatragus, Madoqua, Oreotragus, Nesotragus, and Neotragus are scattered across the bovid phylogenetic tree. Nevertheless, the shared similarities, not only in body size and horn length but also in their social organisation, are interpreted to represent shared plesiomorphic traits that were present in the most recent common ancestor of Antilopinae. Most dwarf antelopes are closely related to gazelles and their allies, placed in the taxon Antilopini. Using a species level phylogeny of this group, I reconstructed ancestral states of several characters for the most recent common ancestor of Antilopini. While the results for the reconstruction of ancestral social organisation of the dwarf species are inconclusive, the small body size and short horns of Ourebia, Raphicerus, Dorcatragus, and Madoqua are most likely derived traits. The habitus of the ancestor of Antilopini was probably very similar to modern gazelles, consistent with the placement of the earliest fossil Antilopini in the genus Gazella.