Basicranial morphology of the early tertiary tarsiiform Rooneyia from Texas.

The newly prepared middle ear cavity of Rooneyia viejaensis revealed the enlarged lateral branch of the internal carotid, an ancestral tarsiiform but advanced primate character. The ectotympanic is well inside the bulla proper and it appears that the annulus membrane and the tissues of the external auditory tube became ossified to form the tarsiiform ectotympanic. The polarity of several character clines of tarsiiform basicrania are discussed. Evidence is lacking from basicranial morphology to corroborate the hypothesized special relationship of microchoerine omomyids and Tarsius.