Amphicyonidae

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Ordo: Carnivora
Subordo: Caniformia
Familia: †Amphicyonidae
Genus: Maemohcyon

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Amphicyonidae is an extinct family of large terrestrial carnivores belonging to the suborder Caniformia (meaning "dog-like") and 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.[1]
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Taxonomy

Amphicyonidae was named by Haeckel (1886) [also attributed to Trouessart 1885]. It was assigned to Carnivora by Sach and Heizmann (2001); to Arctoidea by Hunt (2001), Hunt (2002) and Hunt (2002); affirmed as Arctoidea by Zhai et al. (2003); affirmed to Arctoidea by Carroll (1988), Hunt (1998) and Wang et al. (2005); and to Caniformia by Morlo et al. (2007).[2][3][4]

Origins

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 approximately 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.[5] Note that the (often similar looking) members of the family Hemicyonidae are often called "bear-dogs" as well (although they are increasingly referred to as "dog-bears" to avoid confusion).

Amphicyonids were as small as 5 kilograms (11 lb) and as large as 100 to 200 kilograms (220 to 440 lb) and evolved from wolf-like to bear-like.[6] The diet of the amphicyonids was fully carnivorous as opposed to hypercarnivorous to mesocarnivorous in Canidae.[7]

Evolution

While amphicyonids have traditionally been viewed as closely related to ursids (bears), some evidence suggests that they may instead be basal caniforms. (Hunt, 2004b). They were about as tall as the American black bear and were most likely ambushers due to the fact that their legs were made for short, sudden bursts of speed. Bear-dog also nested their young in underground burrows.

During the early Miocene, a number of large amphicyonids migrated from Eurasia into North America. These taxa belong to the Old World amphicyonid sub-family Amphicyoninae. The earliest to appear is the large bear dog Ysengrinia Ginsburg, followed by Cynelos Jourdan, and then by Amphicyon. This influx of amphicyonines, accompanied by other Old World ungulates and small mammals, indicates a prolonged interval (from 23 to 16.5 Ma) of faunal exchange between Asia and North America in the early Miocene, using the trans-Beringian route[5]. New World daphoenines (Daphoenodon, Borocyon) and temnocyonines coexisted with Old World amphicyonines (Ysengrinia, Amphicyon, Cynelos) 23.7-17.5 million years ago. These are the largest terrestrial carnivorans 50 kilograms (110 lb) to 200 kilograms (440 lb) that evolved on the North American continent up to this time. The immigrant amphicyonines Ysengrinia, Cynelos and Amphicyon appear at 23, 19.2, and 18.8 Ma, respectively, and herald the beginning of a Eurasian amphicyonine migration into North America that continued into the mid-Miocene.[8]

Classification

* Family Amphicyonidae
o Subfamily Amphicyoninae
+ Genus Agnotherium
# A. antiquus
# A. grivense
+ Genus Amphicyon
# A. frendens
# A. bohemicus
# A. castellanus
# A. caucasicus
# A. galushai
# A. giganteus
# A. ingens
# A. intermedius (type)
# 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
o Subfamily Daphoeninae(North America)
+ 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 or Daphoenocyon 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
o Subfamily Temnocyoninae (North America)
+ Genus Mammacyon
# M. obtusidens
+ Genus Temnocyon
# T. altigenis
# T. ferox
# T. percussor
# T. venator
o Subfamily Thanmastocyoninae

References

1. ^ Paleobiology Database: Amphicyonidae, age range and collections
2. ^ V. J. Sach and E. P. J. Heizmann. 2001. Stratigraphy and mammal faunas of the Brackwassermolasse in the surroundings of Ulm (Southwest Germany). Stuttgarter Beiträge zur Naturkunde Serie B (Geologie und Paläontologie) 310:1-95
3. ^ R. M. Hunt. 2001. Small Oligocene amphicyonids from North America (Paradaphoenus, Mammalia, Carnivora). American Museum Novitates 3331:1-20
4. ^ M. Morlo, E. R. Miller, and A. N. El-Barkooky. 2007. Creodonta and Carnivora from Wadi Moghra, Egypt. Journal of Vertebrate Paleontology 27(1):145-159
5. ^ a b Intercontinental Migration of Large Mammalian Carnivores: Earliest Occurrence of the Old World Beardog Amphicyon (Carnivora, Amphicyonidae) in North America, Robert M. Hunt, Jr.
6. ^ Jacobs, Louis L. Jacobs; Scott, Kathleen Marie: Evolution of Tertiary Mammals of North America: Terrestrial carnivores, Cambridge University Press, 1998
7. ^ R. M. Hunt. 1998. Amphicyonidae. 196-227
8. ^ Hunt, Robert M, Jr. (2004b) "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.[1]

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