''Aegyptocetus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

protocetid Protocetidae, the protocetids, form a 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 known (e.g., ''R ...

archaeocete Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene (). Representing the earliest cetacean Evolutionary radiation, radiation, t ...

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

known from

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medit ...

Taxonomy

''Aegyptocetus'' is known from the articulated

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

MSNTUP I-15459, an almost complete cranium,

lower jaw In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

s (with teeth) and a partial

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

l skeleton (cervical and thoracic

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

e and ribs). The specimen was recovered when

marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Marble is typically not foliated (layered), although there are exceptions. In geology, the term ''marble'' refers to metamorphose ...

ized limestone was imported commercially to Italy. It was collected in the Khashm el-Raqaba limestone quarry (, paleocoordinates ) from the Gebel Hof Formation on the northern flank of Wadi Tarfa in the

Eastern Desert The Eastern Desert (Archaically known as Arabia or the Arabian Desert) is the part of the Sahara desert that is located east of the Nile river. It spans of North-Eastern Africa and is bordered by the Nile river to the west and the Red Sea an ...

, dating to the late

Mokattam The Mokattam ( arz, المقطم , also spelled Muqattam), also known as the Mukattam Mountain or Hills, is the name of a range of hills and a suburb in them, located in southeastern Cairo, Egypt. Etymology The Arabic name ''Mokattam'' ...

ian age of the middle

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

, about . Its cause of death may have been an attack by a large

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...

as pattern of shark tooth marks preserved on the ribs. ''Aegyptocetus'' was first named by Giovanni Bianucci and Philip D. Gingerich in 2011 and the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is ''Aegyptocetus tarfa''. The generic name is derived from ''Aegyptus'',

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

for Egypt, and ''cetus'', Latin for whale. The specific name refers to Wadi Tarfa, the desert valley where the holotype was found.

Description

''Aegyptocetus'' had features in its cranium and dentaries adapted for hearing in water. Its thoracic vertebrae (T1–T8), however, had long

neural spine The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

s which is a characteristic of the weight-bearing system of land-living mammals retained in protocetids, such as ''

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 ...

'' and ''

Qaisracetus ''Qaisracetus'' is an extinct protocetid early whale known from the Eocene (Lutetian, ) of Baluchistan, Pakistan (, paleocoordinates ). Etymology The genus is named after the Qaisrani Baloch tribe which assisted Gingerich and his team during ...

'', but absent in the more derived basilosaurids, such as ''

Dorudon ''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'' ...

''. This suggests that ''Aegyptocetus'', like other protocetids, was able to support its body on land and probably was semi-aquatic.

References

Notes

Sources

* {{Taxonbar, from1=Q28605495, from2=Q3605934 Protocetidae Eocene mammals of Africa Fossil taxa described in 2011 Prehistoric cetacean genera