Hemicyon
Encyclopedia
Hemicyon the so-called "dog-bear," literally "Half Dog" (Greek:ἡμικυων/"hemi-kuôn"), is an extinct genus
of the family
Hemicyonidae
, which probably originated in Eurasia but was found in Europe
, Asia
and North America
during the Miocene
epoch , existing for approximately .
and highly predaceous. Unlike modern bears, Hemicyon walked on its toes, that is, it was not plantigrade
, but digitigrade
, with long metapodials
. This suggests that Hemicyonidae must have been an active hunter and a good runner, and presumably hunted on the plains, possibly in packs. This also distinguishes it from the true bears, which are plantigrade, and gives it a greater affinity to dogs, which are digitigrade.
local fauna. This record of Hemicyon represents the earliest occurrence of this genus in North America. The Thomas Farm Cynelos Hemicyon is very closely related to European representatives from the early Burdigalian (ca. 20 million years ago). Other Hemicyon fossil finds include: H. teilhardi from the Middle Miocene Hujialian Formation in the Linxia Basing, Gansu Province, China; an Early Miocene Hemicyon from Lanzhu Basin Shan Mong fauna, China; Hemicyon of the Mid-Miocene Dongxiang and Laogou Formation in Linxia Basin on the northeast margin of the Tibetan Plateau; Mid-Miocene H. sansaniensis of Arroyo del Val area, Villafeliche, Zaragoza Province, Spain; Mid-Miocene H. mayorali of Tarazona de Aragon, Spain; a Hemicyon found at the Somosaguas site, Pozuelo de Alarcón, Madrid; H. sansaniensis from the Mid-Miocene Anchitherium fauna of İnönü locality, NW Ankara; a Lower Miocene (Eggenburgian-Ottnangian: ca. 20 Ma) H stehlini found in the coal bed of Banovići Basin, Bosnia; an Early Hemingfordian Hemicyonid (ca. 16 Ma) from the Pollack Farm Fauna, Delaware; and an excellent Hemicyon specimen from the Miocene Sante Fe Formation, New Mexico.
Hemicyonidae fossil evidence may also have been found in the Gaillard Cut Local Fauna, former Canal Zone, Republic of Panama, but it is indeterminant with Amphicyonidae. Despite its close proximity to South America, given the geological context, the Gaillard Cut Local Fauna are distinctly North American fauna and the age of this assemblage is dated between 19.5 and 14 Ma.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Hemicyonidae
Hemicyonidae
Hemicyonidae is an extinct family of so-called "dog-bears", literally "Half Dog" , bear-like carnivoran living in Europe, North America, Africa, and Asia during the Oligocene through Miocene epochs 33.9—5.3 Ma, existing for approximately ....
, which probably originated in Eurasia but was found in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
during the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
epoch , existing for approximately .
Morphology
Hemicyon was about 1.5 metres (4.9 ft) long, and 70 centimetres (27.6 in) tall, with somewhat tiger-like proportions and dog-like teeth. Hemicyon is widely accepted to have been hypercarnivorousHypercarnivore
A hypercarnivore is an animal which has a diet that is more than 70% meat, with the balance consisting of non-animal foods such as fungi, fruits or other plant material. Some examples include the big cats, dolphins, eagles, snakes, marlin, most sharks, and such invertebrates as octopuses and sea...
and highly predaceous. Unlike modern bears, Hemicyon walked on its toes, that is, it was not plantigrade
Plantigrade
right|151px|thumb|Human skeleton, showing plantigrade habitIn terrestrial animals, plantigrade locomotion means walking with the podials and metatarsals flat on the ground. It is one of three forms of locomotion adopted by mammals...
, but digitigrade
Digitigrade
A digitigrade is an animal that stands or walks on its digits, or toes. Digitigrades include walking birds , cats, dogs, and many other mammals, but not plantigrades or unguligrades...
, with long metapodials
Metatarsus
The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...
. This suggests that Hemicyonidae must have been an active hunter and a good runner, and presumably hunted on the plains, possibly in packs. This also distinguishes it from the true bears, which are plantigrade, and gives it a greater affinity to dogs, which are digitigrade.
Body mass
Two specimens were examined by Legendre and Roth for body mass. The first specimen was estimated to have a weight of 67.2 kg (148.2 lb). The second specimen was estimated to have a weight of 534.5 kg (1,178.4 lb).Fossil sites
Species of Hemicyon are recognized in the medial Hemingfordian (ca. 18 million years ago) Thomas Farm siteThomas Farm Site
The Thomas Farm site is an Early Miocene, Hemingfordian assemblage of vertebrate fossils located in Gilchrist County, northern Florida.The Thomas Farm site is one of the richest terrestrial deposits of Miocene vertebrates in the 18 Ma range found in eastern North America according to the Florida...
local fauna. This record of Hemicyon represents the earliest occurrence of this genus in North America. The Thomas Farm Cynelos Hemicyon is very closely related to European representatives from the early Burdigalian (ca. 20 million years ago). Other Hemicyon fossil finds include: H. teilhardi from the Middle Miocene Hujialian Formation in the Linxia Basing, Gansu Province, China; an Early Miocene Hemicyon from Lanzhu Basin Shan Mong fauna, China; Hemicyon of the Mid-Miocene Dongxiang and Laogou Formation in Linxia Basin on the northeast margin of the Tibetan Plateau; Mid-Miocene H. sansaniensis of Arroyo del Val area, Villafeliche, Zaragoza Province, Spain; Mid-Miocene H. mayorali of Tarazona de Aragon, Spain; a Hemicyon found at the Somosaguas site, Pozuelo de Alarcón, Madrid; H. sansaniensis from the Mid-Miocene Anchitherium fauna of İnönü locality, NW Ankara; a Lower Miocene (Eggenburgian-Ottnangian: ca. 20 Ma) H stehlini found in the coal bed of Banovići Basin, Bosnia; an Early Hemingfordian Hemicyonid (ca. 16 Ma) from the Pollack Farm Fauna, Delaware; and an excellent Hemicyon specimen from the Miocene Sante Fe Formation, New Mexico.
Hemicyonidae fossil evidence may also have been found in the Gaillard Cut Local Fauna, former Canal Zone, Republic of Panama, but it is indeterminant with Amphicyonidae. Despite its close proximity to South America, given the geological context, the Gaillard Cut Local Fauna are distinctly North American fauna and the age of this assemblage is dated between 19.5 and 14 Ma.