Earliest known carnivoran auditory bulla and support for a recent origin of crown-group carnivora (Eutheria, Mammalia)

An ossified auditory bulla of a basal carnivoran is described for the first time. Although broken, the bulla of Viverravus acutus (Viverravidae, Carnivora) appears to have enclosed the middle ear and to have been composed exclusively of an ectotympanic bone. The structure of the bulla and other basicranial features support the hypothesis that viverravids lie phylogenetically outside crown-group Carnivora and that the last common ancestor of living carnivorans may have existed as recently as 42 million years ago, not 60-70 million years ago as suggested by some authors.