New discoveries of hyaenodontids (Creodonta, Mammalia) from the Pondaung Formation, middle Eocene, Myanmar – paleobiogeographic implications

The Pondaung fauna includes approximately 50 species of mammals, including five species of creodonts, of which four have been described. The best known species, Kyawdawia lupina Egi et al., 2005, was recently described based on a fragmentary skull, heavily worn dentitions and postcranial material. On the basis of the Pondaung creodont taxa, previous phylogenetic analyses have suggested a paleobiogeographic Africa-Asia connection during the Eocene, hence a close phylogenetic relationship between Afro-Arabian and Southeast Asian taxa (so-called “Afro-Asian proviverrines” by previous authors). Here, we doubt the natural existence of such a clade on the basis of new hyaenodontid material discovered in the Pondaung Formation, including localities from which creodonts were previously unknown. The new material consists of well preserved, mostly unworn dental remains of two species: 1) Kyawdawia lupina documented here by teeth, or portions of teeth unavailable or poorly preserved in the hypodigm of this species; and 2) Hyaenodontidae sp. indet. Thanks to this material and to a direct study of a great number of hyaenodontids, we analysed the arguments supporting a relationship between Asian and African taxa. This relationship is not supported by our analysis due to: 1) previous character misinterpretations resulting partly from the poor preservation of the hypodigm; and 2) configuration of the data matrix in the previous phylogenetic analysis with important characters and taxa missing. Consequently, the alleged paleobiogeographic connection between Asia and Africa in the Eocene appears to be much less supported than previously thought.