''Aegicetus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

protocetid Protocetidae, the protocetids, form a paraphyletic, diverse and heterogeneous group of extinct cetaceans known from Asia, Europe, Africa, South America, and North America. Description There were many genera, and some of these are very well kno ...

whale Whales are a widely distributed and diverse group of fully Aquatic animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea ...

based on a partial skull with much of an associated

postcranial The postcranium ("behind the cranium"; plural: postcrania) or postcranial skeleton in zoology and vertebrate paleontology is the skeleton apart from the skull. The postcranium encompasses the axial skeleton, which includes the entirety of the verte ...

skeleton discovered in

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

.Philip D. Gingerich, Mohammed Sameh M. Antar und Iyad S. Zalmot: "''Aegicetus gehennae'', a new late Eocene protocetid (Cetacea, Archaeoceti) from Wadi Al Hitan, Egypt, and the transition to tail-powered swimming in whales". ''PLoS ONE'' 14(12): e0225391 doi:10.1371/journal.pone.0225391 It lived around 35 million years ago (during the

Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

), making it the youngest known protocetid to date. ''Aegicetus'' was discovered in 2007 at

Wadi El Hitan ( ) is a paleontological site in the Faiyum Governorate of Egypt, some south-west of Cairo. It was designated a UNESCO World Heritage Site in July 2005 for its hundreds of fossils of some of the earliest forms of whale, the archaeoceti (a no ...

( Gehannam Formation) as a relatively complete skeleton and a partial second specimen. They were assigned to a new

and species in 2019 by Philip D. Gingerich ''et al.''

Description

''Aegicetus'' is a medium-sized whale weighing about , and is reported to have been intermediate in form and functionally transitional in having a larger and more powerful vertebral column of a tail-powered swimmer. It differs from ''

Peregocetus ''Peregocetus'' is a genus of early whale that lived in what is now Peru during the Middle Eocene epoch. Its fossil was uncovered in 2011 in the Yumaque Member ( Paracas Formation) of the Pisco Basin at Playa Media Luna by a team consisting of ...

'' by lacking a firm

sacroiliac joint The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. The ...

and from ''

Rodhocetus ''Rodhocetus'' (from ''Rodho'', the geological anticline at the type locality, and ''cetus'', Latin for whale) is an extinct genus of protocetid early whale known from the Lutetian of Pakistan. The best-known protocetid, ''Rodhocetus'' is known ...

'' by having smaller hind feet, indicating it were less capable of moving on land and relied less on its hind limbs to propel through the water.

References

{{Taxonbar, from1=Q104850142, from2=Q91878655 Protocetidae Fossils_of_Egypt Taxa named by Philip D. Gingerich Fossil taxa described in 2019 Monotypic prehistoric cetacean genera