It was originally believed to be descended from mesonychids, according to . However, the redescription of the primitive, semi-aquatic artiodactyl "Indohyus", and the discovery of its cetacean-like inner ear, simultaneously put an end to the idea that whales were descended from mesonychids, while demonstrating that "Pakicetus", and all other cetaceans, are artiodactyls. Thus, "Pakicetus" represents a transitional taxon between extinct land mammals and modern cetaceans.