family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Odobenidae, endemic to coastal regions of the southern
North Sea
The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...
and the southeastern coastal regions of the U.S. during the
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
-
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
. It lived from 13.6 mya—300,000 years ago, existing for approximately .
Taxonomy
The type species, ''Ontocetus emmonsi'', was named by Joseph Leidy in 1859 on the basis of a single tusk-like tooth (USNM 329064) collected by Ebenezer Emmons from the early
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Zanclean) Yorktown Formation of
North Carolina
North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...
.
In the meantime, marine mammals fossils were being unearthed in
Neogene
The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...
deposits in the vicinity of
Antwerp
Antwerp (; ; ) is a City status in Belgium, city and a Municipalities of Belgium, municipality in the Flemish Region of Belgium. It is the capital and largest city of Antwerp Province, and the third-largest city in Belgium by area at , after ...
,
Belgium
Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...
as well as
Suffolk
Suffolk ( ) is a ceremonial county in the East of England and East Anglia. It is bordered by Norfolk to the north, the North Sea to the east, Essex to the south, and Cambridgeshire to the west. Ipswich is the largest settlement and the county ...
,
England
England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
. One of these fossils was identified as an odobenid and named ''Alachtherium cretsii.'' in 1867. An isolated tooth (RBINS 2892) was named ''Trichechodon koninckii'' in 1871. The fossils from Suffolk were named ''Trichechodon huxleyi'' in 1865. For decades, however, ''Ontocetus'' was tossed aside as a physeterid, as the type specimen was believed to have been missing. For example, ''Ontocetus'' was at one time considered a synonym of the physeterid '' Hoplocetus''. In the meantime, further Pliocene walrus fossils were collected from the North Atlantic, including the holotypes of ''Alachitherium antverpiensis'', ''Alachitherium antwerpiensis'', ''Prorosmarus alleni'', and ''Alachitherium africanum''.
In 2008, all specimens of Pliocene odobenids from the North Atlantic region were reviewed following the rediscovery of the ''Ontocetus emmonsi'' holotype in the 1990s. ''T. huxleyi'', ''A. cretsii'', ''A. antwerpiensis'', ''A. antverpiensis'', ''A. africanum'', and ''P. alleni'' were declared junior synonyms of ''O. emmonsi'' based on comparisons with USNM 329064. ''T. koninckii'', however, was found to be undiagnostic and designated a ''
nomen dubium
In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application.
Zoology
In case of a ''nomen dubium,'' it may be impossible to determine whether a ...
''.
In 2024, reassessment of a pair of mandibles from the UK and a mandible from Belgium that had been assigned to ''O. emmonsi'' resulted in the establishment of a second species in the genus, ''O. posti''.
Misassigned species
''O. oxymycterus'' was named by Remington Kellogg in 1925 on the basis of USNM 10923, collected from the middle
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
. It was recombined as ''Scaldicetus oxymycterus'' by Kohno and Ray (2008), since ''O. emmonsi'' was odobenid and ''O. oxymycterus'' was physeteroid. Boersma and Pyenson (2015) made it the type species of the genus ''
Albicetus
''Albicetus'' is a genus of Stem group, stem-sperm whales that lived during the Miocene Epoch, around 15 million years ago, and was discovered in Santa Barbara, California in 1909. It was categorized for decades as belonging to a group of extinc ...