''Amphicyon'' ("ambiguous dog") 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 ...

of large carnivorous bone-crushing mammals, popularly known as

bear dog Amphicyonidae is an extinct family of terrestrial carnivorans belonging to the suborder Caniformia. They first appeared in North America in the middle Eocene (around 45 mya), spread to Europe by the late Eocene (35 mya), and appear in Asi ...

s, of the family

Amphicyonid Amphicyonidae is an extinct family of terrestrial carnivorans belonging to the suborder Caniformia. They first appeared in North America in the middle Eocene (around 45 mya), spread to Europe by the late Eocene (35 mya), and appear in Asi ...

ae,

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus Genus ( plural genera ) is a taxonomic rank used in the biological classifica ...

Amphicyoninae Amphicyoninae is a subfamily of extinct bear-dogs, large terrestrial carnivores belonging to the suborder Caniformia and which inhabited North America, Eurasia, and Africa from ~37.2—2.6 Ma. Amphicyoninae existed for approximately ~. ...

, from the

Burdigalian The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma (million years ago). Preceded by the Aquitanian, the Burdigalian was the first and longest w ...

Epoch until the late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

, and

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

from 16.9 to 2.6 Ma ago, existing for approximately .

Morphology

''Amphicyon'' was the typical bear-dog amphicyonid with morphology similar to both

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 the No ...

and dogs. With its robust build and maximum length of 2.5 m (8 ft), the largest species looked more like a bear than a dog. It had a large heavy

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...

, thick neck, robust limbs and teeth like a wolf. It was probably an omnivore with a lifestyle comparable to that of the

brown bear The brown bear (''Ursus arctos'') is a large bear species found across Eurasia and North America. In North America, the populations of brown bears are called grizzly bears, while the subspecies that inhabits the Kodiak Islands of Alaska is k ...

. The ''Amphicyon'' was very large for predators of its time but this advantage eventually became a disadvantage because its large body mass was too large to take faster prey. ''A. major'' has been estimated to have had a body mass of , while ''A. ingens'' has been estimated around making it one of the largest known

amphicyonid Amphicyonidae is an extinct family of terrestrial carnivorans belonging to the suborder Caniformia. They first appeared in North America in the middle Eocene (around 45 mya), spread to Europe by the late Eocene (35 mya), and appear in Asi ...

Behaviour

''Amphicyon'' is believed to have been an omnivore, but to have tended to eat more meat than plants or other foods. It is widely believed that ''Amphicyon'' lived on its own, unlike wolves. It is thought to have targeted slow or injured large prey like the ''

Chalicotherium ''Chalicotherium'' ( Ancient Greek /, -: pebble/gravel + /, diminutive of / : beast) is a genus of extinct odd-toed ungulates of the order Perissodactyla and family Chalicotheriidae. The genus is known from Europe and Asia, from the ...

'' to feed its large appetite. However, in a new study published in 2020, examination of the relative grinding area of the molars of ''Amphicyon'' indicates that it was purely carnivorous. Both ''Amphicyon'' and its relative, ''

Ischyrocyon ''Ischyrocyon'' is an extinct genus of bear dogs, of the subfamily Amphicyoninae, which inhabited North America during the Late Miocene. It lived ~13.6—10.3 Ma ago, existing for approximately . Behavior In a study published in 2020, exam ...

'' possessed skeletal features that are characteristic of both ambush and pursuit living predators. As such, it is believed that ''Amphicyon'' probably pursued prey for longer distances but at slower speeds than living ambush predators do. Upon catching up to its prey, ''Amphicyon'' probably grabbed its victims with its powerfully muscled forelimbs before killing them by tearing into the prey's ribcage or neck using its large, strong canines set in its narrow snout.

Fossil distribution

''Amphicyon'' has also been found in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

and

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...

. ''Amphicyons youngest range is on the Indian subcontinent, where it disappeared only in the late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58

Species

''Amphicyon major'' lived from 16.9–9.0 Ma, for approximately . Specimens have been found in across

and in western

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula ...

. The species was named by De Blainville in 1841. ''A. major'' was large in size, comparable to a modern lion or tiger. The estimated mass of ''A. major'' is around 180 kg (397 lb) with the functions derived for limb bones and craniodental measurements.

''Amphicyon giganteus'' was a widespread European species that lived during the early

to early

Langhian The Langhian is, in the ICS geologic timescale, an age or stage in the middle Miocene Epoch/Series. It spans the time between 15.97 ± 0.05 Ma and 13.65 ± 0.05 Ma (million years ago) during the Middle Miocene.GeoWhen (2007) The Langhian was ...

, from approximately 20.4–15.9 Mya, with possible material from

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

. The species was first described in 1884 by Kaup.Catalogue of the Fossil Mammalia in the British Museum Natural History, Dept. of Geology, Richard Lydekker A specimen of ''Iberotherium rexmanueli zbyszewskii'' with teeth marks from ''A. giganteus'' was found in

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of th ...

. It is unknown if the young ''Iberotherium'' was attacked or the carcass found and scavenged. The find was described by paleontologists Antunesa et al. in 2006. ''Amphicyon galushai'' represents the first occurrence of ''Amphicyon'' in North America, approximately 18.8–17.5 Mya during the early Hemingfordian. Described by Robert M. Hunt Jr. in 2003, it is mostly known from fossils found in the Runningwater Formation of western

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the sout ...

and includes a complete adult skull, a partial juvenile skull, 3 mandibles and teeth and postcranial elemenents representing least 15 individuals. There is an additional skull fragment from the Troublesome Formation of Colorado. ''A. galushai'' is considered ancestral to the late Hemingfordian species, ''Amphicyon frendens''. ''A. frendens'' lived during the late Hemingfordian, 17.5–15.9 Mya. The species was originally described by W. Matthew in 1924 from specimens found in the middle member of the Sheep Creek Formation, Sioux County, Nebraska.W. D. Matthew. 1924. Third contribution to the Snake Creek Fauna. Bulletin of the American Museum of Natural History 50:59-210 ''A. frendens'' specimens have since been found at sites in Harney and Malheur Counties, Oregon. A specimen examined by S. Legendre and C. Roth in 1988 yielded an estimated body mass of , similar to that of ''

'', ''A. galushai,'' and its co-existing, borophagine competitor, ''

Epicyon ''Epicyon'' ("more than a dog") is a large, extinct, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. ''Epicyon'' existed for about from the Hemingfordian age of the Early Miocene, to the Hemphillia ...

.'' ''Amphicyon ingens'' lived during the early to middle

Barstovian The Barstovian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 16,300,000 to 13,600,000 years BP, a period of . It is u ...

, 15.8–14.0 Mya. The species was originally described by W. Matthew in 1924 from specimens found in the Olcott Formation, Sioux County, Nebraska. Specimens attributed to this species have since been found in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...

and

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

. ''Amphicyon palaeindicus'' is known from the

Bugti Hills Bugti Hills are a range of hills in eastern Balochistan, Pakistan. It includes the tribal tract called Bugti country. 30 million years ago the Haplorrhinies: '' Bugtipithecus inexpectans'', ''Phileosimias kamali'' and ''Phileosimias brahuiorum'' ...

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...

. It was first described by

Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history. Biography Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker ...

in 1876. The exact age of the fossil sites from which it was recovered is unclear, though they seem to range from the late Oligocene to the late

Miocene The Miocene ( ) is the first 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 means "less recen ...

. Its status as an actual species is unclear, as nearly all remains attributed to ''Amphicyon'' in the region were attributed to it. ''Amphicyon lydekkeri'' is known from the Dhok Pathan horizon in

. It was originally described by Pilgrim in 1910 and attributed to its own genus, ''Arctamphicyon''. However, the differences between "''Arctamphicyon''" and ''Amphicyon'' may ultimately be negligible, and it is most likely part of the genus. With the Dhok Pathan deposits dating to the late

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Bear dogs Oligocene caniforms Miocene bear dogs Miocene mammals of Asia Miocene mammals of North America Aquitanian genus first appearances Tortonian extinctions Fossil taxa described in 1836 Prehistoric carnivoran genera