Amphicyonidae is an extinct

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

carnivorans belonging to the suborder Caniformia. They first appeared in North America in 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'', " ...

(around 45 mya), spread to

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 subcontinent of Eurasia and it is located entirel ...

by the late Eocene (35 mya), and appear in

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 ...

by the early

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 ...

(23 mya). They had largely disappeared worldwide by the late Miocene (8 mya), with the latest recorded

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

at the end of the Miocene in

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...

. They were among the first carnivorans to evolve large body size. Later in their history, they came into competition with hesperocyonine and

borophagine The extinct Borophaginae form one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Hesperocyoninae and extant Caninae. Borophaginae, called "bone-crushing dogs", were endemic to North America ...

canids Canidae (; from Latin, ''canis'', " dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found within ...

. As dogs evolved similar body sizes and cranial and dental adaptations, the rise of these groups may have led to their extinction. Amphicyonids are often colloquially referred to as "bear-dogs".

Taxonomy

The family was erected by Haeckel (1886) lso attributed to Trouessart (1885) Their exact position has long been disputed. Some early paleontologists defined them as members of the family Canidae, but the modern consensus is that they form their own family. Some researchers have defined it as the sister clade to ursids ( bears), based on morphological analysis of the ear region. However, cladistic analysis and reclassification of several species of early carnivore as amphicyonids has strongly suggested that they may be basal caniforms, from lineages older than the origin of both bears and dogs.Hunt, Robert M, Jr. (2004
"Global Climate and the Evolution of Large Mammalian Carnivores during the Later Cenozoic in North America"
in ''Cenozoic Carnivores and Global Climate'' by Robert M. Hunt, Jr. ''Bulletin of the American Museum of Natural History'' (285) 139-285

Description

Amphicyonids ranged in size from as small as and as large as and evolved from wolf-like to bear-like body forms. Early amphicyonids, such as ''

Daphoenodon ''Daphoenodon'' is an extinct genus of terrestrial carnivore, which lived in the early Miocene and belonged to the family Amphicyonidae Amphicyonidae is an extinct family of terrestrial Terrestrial refers to things related to land or the ...

'', possessed a digitigrade posture and locomotion (walking on their toes), while many of the later and larger species were plantigrade or semiplantigrade. The amphicyonids were

obligate carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other so ...

s, unlike the Canidae, which are

hypercarnivore A hypercarnivore is an animal which has a diet that is more than 70% meat, either via active predation or by scavenging. The remaining non-meat diet may consist of non-animal foods such as fungi, fruits or other plant material. Some extant exam ...

s or

mesocarnivore A mesocarnivore is an animal whose diet consists of 50–70% meat with the balance consisting of non-vertebrate foods which may include insects, fungi, fruits, other plant material and any food that is available to them. Mesocarnivores are from a ...

s. There is often some confusion with the similar looking (and similarly named) "dog-bears", a more derived group of caniforms that is sometimes classified as a family (

Hemicyonidae Hemicyoninae is an extinct subfamily of Ursidae, often called dog bears (literally "half dog" (Ancient Greek, Greek: )). They were bear-like carnivorans living in Europe, North America, Africa and Asia during the Oligocene through Miocene epoch ...

), but is more often considered a primitive subfamily of ursids (

Hemicyoninae Hemicyoninae is an extinct subfamily of Ursidae, often called dog bears (literally "half dog" (Greek: )). They were bear-like carnivorans living in Europe, North America, Africa and Asia during the Oligocene through Miocene epochs 33.9–5.3&nb ...

Evolution

It has long been uncertain where amphicyonids originated. It was thought that they may have crossed from Europe to North America during the

epoch, but recent research suggests a possible North American origin from the

miacids Miacids are extinct primitive carnivoramorphans within the family Miacidae that lived during the Paleocene and Eocene epochs, about 62–34 million years ago. Miacids existed for approximately . Miacids are thought to have evolved into the ...

''Miacis cognitus'' and ''M. australis'' (now renamed as the genera ''

Gustafsonia ''Gustafsonia'' is an extinct genus of carnivoran belonging to the family Amphicyonidae (a bear dog). The type species, ''Gustafsonia cognita'', was described in 1986 by Eric Paul Gustafson, who originally interpreted it as a miacid and named it ...

'' and ''

Angelarctocyon ''Angelarctocyon'' is an extinct genus of Amphicyonidae (bear dog), which belongs to the order Carnivora. It was originally interpreted as a miacid and named ''Miacis australis'', however recent research has suggested it is an early amphicyonid ...

'', respectively). As these are of North American origin, but appear to be early amphicyonids, it may be that the Amphicyonidae actually originates in North America.Tomiya S., and Tseng Z. J. 2016 Whence the beardogs? Reappraisal of the Middle to Late Eocene ‘Miacis’ from Texas, USA, and the origin of Amphicyonidae (Mammalia, Carnivora). Royal Society Open Science. DOI: 10.1098/rsos.160518 http://rsos.royalsocietypublishing.org/content/3/10/160518 Other New World amphicyonids include the oldest known amphicyonid, ''

Daphoenus ''Daphoenus'' is an extinct genus of bear dogs. ''Daphoenus'' inhabited North America from the Middle Eocene to the Middle Miocene, 37.2—16.0 Mya, existing for approximately . Species ''D. hartshornianus'' fossils found in Oligocene Orellan ...

'' (37–16 Mya). Amphicyonids began to decline in the late Miocene, and disappeared by the end of the epoch. The reasons for this are unclear; possibly it was due to competition with other carnivorans, as large canids had better adaptations to pursue swift prey in open country, a habitat which spread globally as the new grassland biome replaced more closed environments. However, no direct evidence for this idea has been found. The most recent known amphicyonid remains are teeth known from the Dhok Pathan horizon, northern

, dating to 7.4-5.3 mya. The species is classically named ''Arctamphicyon lydekkeri'', which may actually be synonymous with a species of '' Amphicyon''. Fossils of juvenile ''

Agnotherium ''Agnotherium'' is a genus of large sized carnivoran mammals, belonging to the Amphicyonidae ("bear dogs"), which has been found in Western Europe, and possibly Northern Africa, and lived during the Late Miocene epoch. Despite only being known f ...

'', ''

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, examin ...

'', and ''

Magericyon ''Magericyon'' is an extinct genus of Amphicyonid ("bear-dog") that lived during the Miocene 10-9 Ma (Vallesian Age) in what is now Spain. Description The appearance of this animal was vaguely similar to that of a particularly robust, large fel ...

'' all show an unusual type of tooth eruption in which there is a vulnerable stage at about two or three years of age where the subadult animal has no functional molar or

carnassial Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...

teeth, the only functional cheek teeth being several milk premolars. This period was suggested to be "presumably short" but would have made it very difficult for the animal to process food. This type of tooth replacement is not seen in similar carnivorans like

ursids The Ursid (URS) meteor activity begins annually around December 17 and runs for over a week, until the 25th or 26th. This meteor shower is named for its radiant point, which is located near the star Beta Ursae Minoris (Kochab) in the constellati ...

, and may have been one factor in the extinction of the Amphicyonidae.

Classification

* Family Amphicyonidae ** Genus '' Aktaucyon'' *** ''A. brachifacialis'' ** Genus '' Amphicyanis'' ** Genus ''

'' *** ''A. australis'' (formerly ''Miacis australis'') ** Genus ''

Brachycyon '' Brachycyon'' is an extinct genus of terrestrial carnivores belonging to the suborder Caniformia, family Amphicyonidae ("bear dog"), which inhabited Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Euro ...

'' *** ''B. reyi'' *** ''B. palaeolycos'' *** ''B. gaudryi'' ** Genus ''

Gobicyon '' Gobicyon'' is an extinct genus of bear dogs (members of the family Amphicyonidae) endemic to Central Asia during the Late Miocene 13.6—11.6 Ma, existing for approximately . Fossils have been discovered only at Tong Xin in Central China ...

'' *** ''G. acutus'' *** ''G. macrognathus'' *** ''G. yei'' *** ''G. zhegalloi'' ** Genus ''

'' *** ''G. cognita'' (formerly ''Miacis cognitus'') ** Genus '' Guangxicyon'' *** ''G. sinoamericanus'' ** Genus '' Haplocyon'' *** ''H. elegans'' *** ''H. crucians'' ** Genus '' Haplocyonoides'' *** ''H. mordax'' *** ''H. serbiae'' *** ''H. ponticus'' ** Genus '' Haplocyonopsis'' ** Genus '' Harpagocyon'' ** Genus '' Harpagophagus'' ** ''Genus Ictiocyon''Ictiocyon'' at fossilworks
'' ** Genus ''

Myacyon ''Myacyon'' is an extinct genus of large sized carnivoran mammals, belonging to the family Amphicyonidae (“bear dogs”), that lived in Africa during the Miocene epoch. Due to the limited scope and fragmentary nature of the severely damaged holo ...

'' *** ''M. peignei'' ** Genus '' Paradaphoenus'' *** ''P. cuspigerus'' *** ''P. minimus'' *** ''P. tooheyi'' ** Genus ''

Pseudarctos ''Pseudarctos'' is a member of the extinct Family (biology), family Amphicyonidae of Terrestrial animal, terrestrial carnivores belonging to the suborder Caniformia, which inhabited Eurasia in the Middle Miocene subepoch 16.9—11.1 Annum, Ma, ex ...

'' *** ''P. bavaricus'' ** Genus '' Pseudocyonopsis'' *** ''P. ambiguus'' *** ''P. antiquus'' *** ''P. quercensis'' ** Subfamily

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 ~. ...

*** Genus '' Amphicyon'' **** ''A. frendens'' **** ''A. galushai'' **** ''A. giganteus'' **** ''A. ingens'' **** ''A. laugnacensis'' **** ''A. longiramus'' **** ''A. lyddekeri'' **** ''A. major ( type)'' **** ''A. palaeindicus'' *** Genus ''

Cynelos '' Cynelos'' is a large extinct genus of bear dogs which inhabited North America, Europe, and Africa from the Early Miocene subepoch to the Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene Epoch made up ...

'' **** ''C. caroniavorus'' **** ''C. crassidens'' **** ''C. helbingo'' **** ''C. idoneus'' **** ''C. jourdan'' **** ''C. lemanensis'' **** ''C. pivetaui'' **** ''C. rugosidens'' **** ''C. schlosseri'' **** ''C. sinapius'' *** Genus ''

Goupilictis ''Goupilictis minor'' is a prehistoric species of mammal in the family Amphicyonidae. There is only one known species in the genus ''Goupilictis''. Description ''Goupilictis'' lived in the Oligocene and Miocene ages, about 28.4-5.332 milli ...

'' **** ''G. minor'' *** Genus ''

'' **** ''I. gidleyi'' ***Genus ''

'' **** ''M. anceps'' **** ''M. castellanus'' *** Genus ''

Pliocyon ''Pliocyon'' is an extinct genus of bear dogs which inhabited North America during the Middle Miocene 16.0—13.6 Ma, existing for approximately . Fossils have been uncovered in South Florida, Oregon, and western Nebraska Nebraska () is ...

'' **** ''P. medius'' **** ''P. robustus'' *** Genus '' Pseudamphicyon'' *** Genus ''

Pseudocyon ''Pseudocyon'' (False dog) is a genus of bear dog which inhabited Eurasia and North America during the Miocene epoch living approximately . ''Pseudocyon'' was assigned to Amphicyoninae by Hunt in 1988 and to Amphicyonidae by Lartet (1851), Carro ...

'' **** ''P. sansaniensis'' **** ''P. steinheimensis'' **** ''P. styriacus'' *** Genus ''

Tartarocyon ''Tartarocyon'' is an extinct genus of Amphicyonidae, who lived during the late Middle Miocene. It was described after fossilized remains found in Sallespisse, France. Despite the scarceness of its fossil remains, being only known from the holo ...

'' **** ''T. cazanavei'' ** Subfamily

Daphoeninae The Daphoeninae are an extinct subfamily of dog-like, terrestrial carnivores, which belonged to the family Amphicyonidae of the suborder Caniformia. The group inhabited North America from the Middle Eocene subepoch to the Middle Miocene subep ...

(North America) *** Genus '' Adilophontes'' **** ''A. brachykolos'' *** Genus '' Brachyrhyncocyon'' **** ''B. dodgei'' **** ''B. montanus'' *** Genus '' Daphoenictis'' **** ''D. tedfordi'' *** Genus ''

'' **** ''D. falkenbachi'' **** ''D. notionastes'' **** ''D. robustum'' **** ''D. periculosus'' **** ''D. skinneri'' **** ''D. superbus'' *** Genus ''

'' **** ''D. felinus'' **** ''D. hartshornianus'' **** ''D. lambei'' **** ''D. nebrascensis'' **** ''D. socialis'' **** ''D. transversus'' **** ''D. vetus'' ** Subfamily

Temnocyoninae The Temnocyoninae are an extinct subfamily of medium-sized bear dogs endemic to North America that lived during the Early Oligocene to Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), ...

(North America) *** Genus ''

Mammacyon ''Mammacyon'' is an extinct genus of medium-sized bear dogs endemic to North America during the Late Oligocene and Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of t ...

'' **** ''M. ferocior'' **** ''M. obtusidens'' *** Genus ''

Temnocyon ''Temnocyon'' is an extinct genus of bear-dogs endemic to North America. It lived from the Oligocene to Early Miocene approximately 30.8—20.4 mya, existing for about . The first fossils are recorded in North America at Logan Butte in the Joh ...

'' **** ''T. altigenis'' **** ''T. ferox'' **** ''T. percussor'' **** ''T. venator'' ** Subfamily

Thaumastocyoninae Thaumastocyoninae is an extinct subfamily of Amphicyonidae, amphicyonids, large terrestrial carnivores, which inhabited what is now Europe during the Miocene epoch. The subfamily was erected by Hürzeler (1940), and is defined by the complete sup ...

Morales, J., O. Fejfar, E. Heizmann, J. Wagner, A. Valenciano, and J. bella. 2019
A new Thaumastocyoninae (Amphicyonidae, Carnivora) from the early Miocene of Tuchořice, the Czech Republic.
Fossil Imprint 75(3–4): 397–411. *** Genus ''

'' **** ''A. antiquus'' *** Genus '' Ammitocyon'' **** ''A. kainos'' *** Genus '' Crassidia'' **** ''C. intermedia'' *** Genus '' Peignecyon'' **** ''P. felinoides'' *** Genus '' Thaumastocyon'' **** ''T. bourgeoisi'' **** ''T. dirus'' *** Genus '' Tomocyon'' **** ''T. grivense'' *** Genus ''

Ysengrinia ''Ysengrinia'' is an extinct genus of carnivoran in the family Amphicyonidae (beardogs), which lived in Europe, Asia, and North America during the Early Miocene. It was also reported from Egypt and Namibia, but this material has been reassigned ...

'' **** ''Y. americanus'' **** ''Y. depereti'' **** ''Y. geraniana'' **** ''Y. tolosana'' **** ''Y. valentiana''

References

External links

Whence the beardogs? Reappraisal of the Middle to Late Eocene ‘Miacis’ from Texas, USA, and the origin of Amphicyonidae
{{Taxonbar, from=Q248422 Prehistoric mammals of North America Eocene carnivorans Oligocene carnivorans Miocene carnivorans Pliocene extinctions Eocene first appearances Taxa named by Ernst Haeckel Prehistoric mammal families Fossil taxa described in 1886