Basilosauridae

Basilosaurus (meaning "king lizard") is a genus of large, predatory, prehistoric archaeocete whale from the late Eocene, approximately 41.3 to 33.9 million years ago (mya). First described in 1834, it was the first archaeocete and prehistoric whale known to science. Fossils attributed to the type species B. cetoides were discovered in the southeastern United States. The generic name, meaning "king lizard", was given due to the initial misconception about the fossil material as that of a giant reptile. The animal was later found to be an early marine mammal, prompting attempts at renaming the c

Dorudon ("spear-tooth") is a genus of extinct basilosaurid ancient whales that lived alongside Basilosaurus 41.03 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.

Basilosauridae is a family of extinct cetaceans that lived during the middle to late Eocene. Basilosaurids are known from all continents including Antarctica, and are probably the first fully aquatic cetaceans. The group is noted to be a paraphyletic assemblage of stem group whales from which the monophyletic Neoceti are derived.

Perucetus is an extinct genus of an early whale from Peru that lived during the Bartonian age of the middle Eocene. Perucetus is the largest Eocene whale, with length estimates varying from to . It was initially claimed to have rivaled or exceeded the modern blue whale in weight, partly due to the incredibly thick and dense bones this animal possessed, coupled with its already great size, but subsequent studies argued that it was significantly lighter. The ecology of Perucetus also remains largely mysterious. Based on the fossils, it was likely a slow-moving inhabitant of shallow waters. Its d

Zygorhiza ("Yoke-Root") is an extinct genus of basilosaurid early whale known from the Late Eocene (Priabonian, 38–34 Ma) of Louisiana, Alabama, and Mississippi, United States, and the Bartonian (43–37 Ma on the New Zealand geologic time scale) to the late Eocene of New Zealand (). Specimens reported from Europe are considered Dorudontinae incertae sedis.

Cynthiacetus is an extinct genus of basilosaurid early whale that lived during the Late Eocene (Bartonian-Priabonian, .) Specimens have been found in the southeastern United States and Peru (Otuma Formation).

Saghacetus is an extinct genus of basilosaurid early whale, fossils of which have been found in the Upper Eocene (middle Priabonian, ) Qasr el Sagha Formation, Egypt (, paleocoordinates ).

Basiloterus is an extinct genus of late-Eocene archaeocete whale from the Drazinda Formation in southwestern Punjab, Pakistan and possibly also the Barton Group (originally Barton Beds) of England. Known from two isolated lumbar vertebrae, the elongated nature of these elements has been taken as possible evidence that Basiloterus was a close relative of the better-known Basilosaurus. This was also the reasoning behind its name, which roughly translates to "another king". However, publications since then not only lead to some major changes of the internal relationships within Basilosauridae but

Dorudontinae are a group of extinct cetaceans that are related to Basilosaurus.

Supayacetus is an extinct genus of basilosaurid cetacean from the Middle Eocene (Bartonian stage) Paracas Formation of Peru. It has been noted for its relatively small size and basal morphology, with the sternum bearing close resemblance to those of protocetids. Due to this, it has been traditionally placed as one of the basalmost basilosaurids, except for a 2023 study that places it within the family Pachycetinae close to Neoceti. Supayacetus is monotypic, meaning the genus includes only a single species: S. muizoni.

Masracetus (from Arabic Masr, "Egypt", and Greek ketos, "whale") is an extinct genus of basilosaurid ancient whale known from the Late Eocene (Priabonian, ) of Egypt.

Chrysocetus is a genus of extinct archaeocete ceteceans belonging to the Basilosauridae that is known from the Late Eocene of the eastern United States and western Africa. Across its range two species are known, the American Chrysocetus healyorum and the African Chrysocetus fouadassii, named in 2001 and 2015 respectively. Chrysocetus was a comparably small basilosaurid, larger than Saghacetus and Tutcetus but smaller than most other members of this group. In addition to being noted for its well-preserved hip bones, Chrysocetus is unique amongst basilosaurids for possibly having only had a sing

Stromerius is an extinct genus of basilosaurid early whale known from the Late Eocene (Priabonian, ) of Fayum, Egypt (, paleocoordinates ).

Basilosaurinae is a subfamily of cetaceans archaeocetes containing two genera: Basilosaurus and Basiloterus. They were characterized by elongated distal thoracic vertebrae, lumbar, and proximal sacrococcygeal. All known members of the subfamily are larger than their relatives of the Dorudontinae subfamily except Cynthiacetus.

Tutcetus is an extinct genus of diminutive basilosaurid cetacean from the Bartonian of Egypt. Tutcetus, named after the child pharaoh Tutankhamun, is both one of the oldest known basilosaurids from Africa and the smallest member of the family. It is suggested that the type specimen, a subadult close to maturity, only measured approximately long. The genus is monotypic, only including the species T. rayanensis.

Ocucajea is an extinct genus of basilosaurid cetacean from Middle Eocene (Bartonian stage) deposits of southern Peru. Ocucajea is known from the holotype MUSM 1442, a partial skeleton. It was collected in the Archaeocete Valley site, from the Paracas Formation of the Pisco Basin about .

Ancalecetus (from Greek ankale, "bent arm", and ketos, "whale") is an extinct genus of early whale known from the Late Eocene (Priabonian, ) Birket Qarun Formation (, paleocoordinates ) in Wadi Al-Hitan, Egypt. The species is named after anthropologist and primate researcher Elwyn L. Simons who discovered the type specimen in 1985.