Amphicyon ingens skeleton
The Amphicyonidae is an extinct family of large terrestrial carnivores, which inhabited North America, Europe, Asia, and Africa from the Middle Eocene subepoch to the Pleistocene epoch 46.2—1.8 Mya, existing for approximately 44.4 million years.
Amphicyonids, often referred to as "bear dogs", crossed from Europe to North America during the Miocene epoch and are considered an Old World taxon. The earliest to appear is the (rather large) Ysengrinia (30—20 Mya), followed by Cynelos (24—7 Mya) and Amphicyon (23—5 Mya). These animals would have followed ungulates and other mammals to the New World for a period of about 7 million years. The New World amphicyonids of the subfamilies Daphoeninae (42-16 Mya) and Temnocyoninae (33-20 Mya) coexisted with the Old World counterparts. Note that the (often similar looking) members of the family Hemicyonidae are also often called "bear-dogs".
Amphicyonids were as small as 5 kg (11 lb) and as large as 100 to 600 kg (220 to 1,300 lb) and evolved from wolf-like to bear-like. Early amphicyonids, such as Daphoenodon, 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 carnivores, unlike the Canidae, which are hypercarnivores or mesocarnivores.
While amphicyonids have traditionally been viewed as closely related to ursids (bears), some evidence suggests they may instead be basal caniforms. (Hunt, 2004b). They were about as tall as the American Black Bear and were most likely ambushers because their legs were made for short, sudden bursts of speed. Bear dogs also nested their young in underground burrows.
Genus Agnotherium A. antiquus A. grivense Genus Amphicyon A. frendens A. bohemicus A. castellanus A. caucasicus A. galushai A. giganteus A. ingens A. intermedius A. laugnacensis A. longiramus A. major A. pontoni A. reinheimeri A. riggsi A. tairumensis A. ulungurensis Genus Amphicyonopsis A. serus Genus Brachycyon B. reyi B. palaeolycos B . gaudryi Genus Cynelos C. caroniavorus C. crassidens C. helbingo C. idoneus C. jourdan C. lemanensis C. pivetaui C. rugosidens C. schlosseri C. sinapius Genus Cynodictis C. lacustris Genus Euroamphicyon E. olisiponensis Genus Gobicyon G. macrognathus G. zhegalloi Genus Guangxicyon G. sinoamericanus Genus Haplocyon H. elegans H. crucians Genus Haplocyonoides H. mordax H. serbiae H. ponticus Genus Haplocyonopsis Genus Harpagocyon Genus Heducides Genus Ischyrocyon I. gidleyi Genus Paradaphoenus P. cuspigerus P. minimus P. tooheyi Genus Pericyon Genus Pliocyon P. medius P. robustus Genus Proamphicyon Genus Protemnocyon Genus Pseudarctos P. bavaricus Genus Pseudamphicyon P. bavaricus Genus Pseudocyon P. sansaniensis P. steinheimensis P. styriacus Genus Pseudocyonopsis P. ambiguus P. antiquus P. quercensis Genus Symplectocyon Genus Ysengrinia Y. americanus Y. depereti Y. geraniana Y. ginsburg Y. tolosana
Genus Adilophontes A. brachykolos Genus Borocyon Genus Brachyrhyncocyon B. dodgei B. montanus Genus Daphoenictis D. tedfordi Genus Daphoenodon D. falkenbachi D. notionastes D. robustum D. periculosus D. skinneri D. superbus Genus Daphoenus D. dodgei D. felinus D. hartshornianus D. inflatus D. lambei D. nebrascensis D. socialis D. transversus D. vetus Genus Paradaphoenus P. cuspigerus P. minimus P. tooheyi
Genus Mammacyon M. obtusidens Genus Temnocyon T. altigenis T. ferox T. percussor T. venator