Robert West was the first to identify pakicetids as cetaceans in 1980 and, after discovering a braincase, Phillip Gingerich and Donald Russell described the genus Pakicetus in 1981.

[2] Pakicetids have been found in or near river deposits in northern Pakistan and northwestern India, a region which was probably arid with only temporary streams when these animals lived there.

During the Eocene, Pakistan was an island-continent off the coastal region of the Eurasian land mass and therefore an ideal habitat for the evolution and diversification of the Pakicetids.

The tympanic bulla in pakicetid ears is similar to those in all cetaceans, with a relatively thin lateral wall and thickened medial part known as the involucrum.

Motion in the spine of pakicetids was further reduced by the revolute zygapophyses (processes between the vertebrae) like in stiff-backed runners such as mesonychians.

The deltopectoral crests are absent in the long and slender humeri like in cursorial animals but unlike other Eocene cetaceans.

[5] Gingerich 2003 disagreed and got support from Madar 2007: postcranial morphology and microstructural features suggest that pakicetids were adapted to an aquatic lifestyle which included bottom wading, paddling, and undulatory swimming, but probably not sustained running.