extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
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 ...
of
Hippopotamidae
Hippopotamidae is a family of stout, naked-skinned, and semiaquatic artiodactyl mammals, possessing three-chambered stomachs and walking on four toes on each foot. While they resemble pigs physiologically, their closest living relatives are th ...
that lived between 7.5 and 2.58 million years ago in
Africa
Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...
and the
Middle East
The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq.
The term came into widespread usage by the United Kingdom and western Eur ...
. The genus was described in 2005 to encompass species of
hippos
A hippo or hippopotamus is either of two species of large African mammal which live mainly in and near water:
* Hippopotamus
* Pygmy hippopotamus
Hippo or Hippos may also refer to:
Toponymy
* The ancient city of Hippo Regius (modern Annaba, Alg ...
that were previously grouped in '' Hexaprotodon''.
''Archaeopotamus'' means "the ancient of the river". Of all identified hippos, only '' Kenyapotamus'' is older. '' Kenyapotamus'', however, is only known from partial
fossils
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
; ''Archaeopotamus'' is the oldest well-identified hippo.
Characteristics
Many prehistoric hippo fossils are known primarily through fossils of the
lower jaw
In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla).
The jawbone i ...
. ''Archaeopotamus'', like ''Hexaprotodon'', has three pairs of
incisors
Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...
. Unlike other ''Hexaprotodon'', ''Archaeopotamus'' has a highly elongate
mandibular symphysis
In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral ha ...
. The informal name "narrow muzzled hippos" has been suggested for this genus.
''A. lothagamensis''
''A. lothagamensis'' is a species whose fossils were discovered at Lothagam, a site southwest of
Lake Turkana
Lake Turkana () is a saline lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. By volume it is the world ...
in
Kenya
Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
and first described in 2000. When first described, the species was classified as ''Hexaprotodon lothagamensis'', although the significant morphological differences between other ''Hexaprotodon'' species, were noted.
''A. lothagamensis'' was smaller than the modern
hippopotamus
The hippopotamus (''Hippopotamus amphibius;'' ; : hippopotamuses), often shortened to hippo (: hippos), further qualified as the common hippopotamus, Nile hippopotamus and river hippopotamus, is a large semiaquatic mammal native to sub-Sahar ...
and also smaller than ''A. harvardi'' and with a more slender skeleton. It was, however, significantly larger than the modern
pygmy hippopotamus
The pygmy hippopotamus or pygmy hippo (''Choeropsis liberiensis'') is a small Hippopotamidae, hippopotamid which is native to the forests and swamps of West Africa, primarily in Liberia, with small populations in Sierra Leone, Guinea, and Ivory Co ...
.
''A. harvardi''
''A. harvardi'' is a species of hippo first described in 1977, originally as ''Hexaprotodon harvardi''. Although the proportions of ''A. harvardi'' and ''A. lothagamensis'' are similar, the former species is significantly smaller. Femurs of ''A. harvardi'' are approximately the same size as those of the modern hippopotamus.
Another group of fossils, originally described as ''Hexaprotodon sahabiensis'' or the Abu Dhabi Hippopotamus, are now considered to belong to ''A. harvardi'' or ''A. lothagamensis''. The fossil record for ''A. harvardi'' is more extensive than for other ''Archaeopotamus''.
''A. harvardi'' is believed to have had a more
riparian
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...
lifestyle than ''A. lothagamensis''.
Distribution
Fossils of ''Archaeopotamus'' have been unearthed near
Lake Turkana
Lake Turkana () is a saline lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. By volume it is the world ...
, Kenya; near
Lake Victoria
Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropics, tropical lake, and the world's second-largest fresh water lake by surface are ...
in Kenya and in
Abu Dhabi
Abu Dhabi is the capital city of the United Arab Emirates. The city is the seat of the Abu Dhabi Central Capital District, the capital city of the Emirate of Abu Dhabi, and the UAE's List of cities in the United Arab Emirates, second-most popu ...
and thus likely ranged across
East Africa
East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...
and the
Arabian Peninsula
The Arabian Peninsula (, , or , , ) or Arabia, is a peninsula in West Asia, situated north-east of Africa on the Arabian plate. At , comparable in size to India, the Arabian Peninsula is the largest peninsula in the world.
Geographically, the ...
. The species ''A. pantanelli'' inhabited
Tuscany
Tuscany ( ; ) is a Regions of Italy, region in central Italy with an area of about and a population of 3,660,834 inhabitants as of 2025. The capital city is Florence.
Tuscany is known for its landscapes, history, artistic legacy, and its in ...
,
Italy
Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
.
Evolution
The immediate ancestor of ''Archaeopotamus'' is unknown. Whether ''Archaeopotamus'' is descended from '' Kenyapotamus'' cannot be determined from the few fossils available. Although ''Archaeopotamus'' is more primitive than any member of the genus ''Hippopotamus'', it is likely a sister group of both hippopotamuses and ''Hexaprotodon''.
Fossils similar to ''Archaeopotamus'' have been dated to as recently as about 2 million years ago, the end of the