Agriotherium
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''Agriotherium'' is an extinct genus of
bears Bears are carnivoran mammals of the family Ursidae (). They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout most o ...
whose fossils are found in
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 ...
through
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 ...
-aged strata of
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
,
Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
, and
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 ...
. The earliest species, ''A.'' ''aecuatorialis'' evolved during the early
Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
, around 11.6 Mya. The last species, ''A. africanum'', going extinct 2.58 Mya, during the late
Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58 ''A. africanum'' measured around in body length and weighed up to , making it larger than most living bears; however, mass estimates vary, with further studies presenting a lower mass estimate of . Along with other large bears such as the
cave bear The cave bear (''Ursus spelaeus'') is a prehistoric species of bear that lived in Europe and Asia during the Pleistocene and became extinct about 24,000 years ago during the Last Glacial Maximum. Both the word ''cave'' and the scientific name '' ...
, short-faced bears ''
Arctodus ''Arctodus'' is an extinct genus of short-faced bear that inhabited North America during the Pleistocene (~2.6 Year#mya, Mya until 12,800 years ago). There are two recognized species: the lesser short-faced bear (''Arctodus pristinus'') and the gia ...
'' and ''
Arctotherium ''Arctotherium'' ("bear beast") is an extinct genus of the Pleistocene Tremarctinae, short-faced bears endemic to Central America, Central and South America. ''Arctotherium'' migrated from North America to South America during the Great American In ...
'', and an extinct subspecies of the modern polar bear '' Ursus maritimus tyrannus'', ''Agriotherium'' was among the largest known terrestrial members of
Carnivora Carnivora ( ) is an order of placental mammals specialized primarily in eating flesh, whose members are formally referred to as carnivorans. The order Carnivora is the sixth largest order of mammals, comprising at least 279 species. Carnivor ...
. They had longer legs and shorter faces than other bears, and were more lightly built. Their wide, short jaws could generate enormous bite force. It is not certain how this force was used by the living animal; a study designed to determine how the genus fed discovered that among living bears, the lowest bite force belongs to the predatory polar bear, which feeds largely on blubber, and the highest bite force belongs to the giant panda, a herbivore which uses it to crush
bamboo Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...
. Shortened jaws with high bite forces are found in other mammals like Gelada baboons that eat grasses but evolved from non-grazing ancestors, and in bone-crushing scavengers, like
spotted hyena The spotted hyena (''Crocuta crocuta''), also known as the laughing hyena, is a hyena species, currently classed as the sole extant member of the genus ''Crocuta'', native to sub-Saharan Africa. It is listed as being of least concern by the IUC ...
s and borophagine dogs. Analysis of the teeth, jaw, and tooth wear patterns identifies ''Agriotherium'' as an
omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...
that ate a lot of plant material. Though its teeth do not show adaptations for a carnivorous diet, isotope evidence suggests it did eat a significant amount of animal material, similar to some populations of modern
brown bear The brown bear (''Ursus arctos'') is a large bear native to Eurasia and North America. Of the land carnivorans, it is rivaled in size only by its closest relative, the polar bear, which is much less variable in size and slightly bigger on av ...
s. Several studies of the skeleton, including a comparison with '' Hemicyon ursinus,'' a fossil bear widely accepted as a
predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
, show that ''Agriotherium'' did not have the limb strength or speed needed for active hunting, either by ambush or by chasing down prey. It also did not show the long claws and increased forelimb strength typical of mammals that dig for food. These very large bears may have specialized on a combination of grazing, eating fruit and invertebrate food in season, and intimidating predators away from carcasses in order to scavenge meat and bone marrow. Very large size would have been necessary to steal and defend kills in environments dominated by some of the most powerful
carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...
mammals that have ever lived, such as the sabertooth cat '' Amphimachairodus'', with whom it shared territory in both Afro-Eurasia and North America, and the bone-cracking
canid Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...
'' Epicyon'' and the massive feliform sabertooth '' Barbourofelis'', which it lived alongside in Texas, as evidenced by fossil deposits at Coffee Ranch. Its name was made from the Greek for "wild beast".


Fossil distribution

Sites and age of specimens: *Venta del Moro,
Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
~9–5.3 Ma. *Lang. E Quarry,
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
~5.3–3.6 Ma. *Vialette, Haute Loire,
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
~3.2–2.5 Ma. *Middle Awash,
Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...
~11.6–3.6 Ma. ''Agriotherium'' ranged widely; fossils of four or more species have been found in
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
,
Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...
,
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
, and
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
. It is the only ursoid known to have colonized
sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
.


References


Sources

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External links


Illustration at ScienceArt
{{Taxonbar, from=Q2333795 Miocene bears Pliocene bears Cenozoic mammals of Europe Cenozoic mammals of Africa Cenozoic mammals of Asia Cenozoic mammals of North America Prehistoric carnivoran genera Pleistocene bears Pleistocene carnivorans Pleistocene extinctions Fossil taxa described in 1837 Ailuropodinae