Dorudon ("spear-tooth") is a genus of extinct basilosaurid ancient whales that lived alongside Basilosaurus 40.4 to 33.9 million years ago in the Eocene. It was a small whale, with D. atrox measuring long and weighing . Dorudon lived in warm seas around the world and fed on small fish and mollusks. Fossils have been found along the former shorelines of the Tethys Sea in present-day Egypt and Pakistan, as well as in the United States, New Zealand, and Western Sahara. Taxonomic history described Dorudon serratus based on a fragmentary maxilla and a few teeth found in South Carolina. He concluded that the teeth must have belonged to a mammal since they were two-rooted, that they must have been teeth from a juvenile since they were hollow, and also noted their similarity to the teeth then described for Zeuglodon (Basilosaurus). When exploring the type locality, Gibbes discovered a lower jaw and twelve caudal vertebrae, which he felt obliged to assign to Zeuglodon together with his original material. Gibbes concluded that Dorudon were juvenile Zeuglodon and consequently withdrew his new genus. He did however allow Louis Agassiz at Harvard to examine his specimens, and the Swiss professor replied that these were neither teeth of a juvenile nor those of Zeuglodon, but of a separate genus just as Gibbes had first proposed. described Prozeuglodon atrox (="Proto-Basilosaurus") based on a nearly complete skull, a dentary, and three associated vertebrae presented to him by the Geological Museum of Cairo. , however, realized that Andrews' specimen was a juvenile, and, he assumed, the same species as Zeuglodon isis, described by Andrews 1906. Kellogg also realized that the generic name Zeuglodon was invalid and therefore recombined it Prozeuglodon isis. Since then many specimens have been referred to Prozeuglodon atrox, including virtually every part of the skeleton, and it has become obvious that it is a separate genus, not a juvenile "Proto-Zeuglodon". Kellogg placed several of the species of Zeuglodon described from Egypt in the early 20th century (including Z. osiris, Z. zitteli, Z. elliotsmithii, and Z. sensitivius) in the genus Dorudon. synonymized these four species and grouped them as Saghacetus osiris. The current taxonomic status of Dorudon is based on 's revision of Dorudon and detailed description of D. atrox. Before this, the taxonomy of Dorudon was in disarray and based on a limited set of specimens. D. atrox is known from Egypt, D. serratus from Georgia