Gobicyon

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Gobicyon is an extinct, large carnivoran from the amphicyonid family, also called bear dogs. It lived during the Middle Miocene, roughly 16 to 11.5 million years ago, in what is now China, Mongolia, and Serbia. It is known mainly from jaws and teeth, and it shows bone-crushing adaptations similar to those of hyenas. Gobicyon is considered an unusual member of the Haplocyoninae and is closely related to the Kazakh genus Aktaucyon.

Discovery and what it is known from
- Described in 1939 by Edwin Colbert from a jaw fossil found in Inner Mongolia’s Tunggur Formation.
- A Serbian jaw (described in 1959) was initially linked to Gobicyon but later reinterpreted; similarities to G. macrognathus were recognized.
- Gobicyon zhegalloi was described in 1981 from Mongolia.
- A major 2019 review added two new Chinese species and expanded knowledge of the genus’s diversity.
- Gobicyon remains are mostly cranial and dental, so body size is estimated from skulls and teeth.

Species and key traits
- Gobicyon macrognathus (type species): The best-known member, found in Inner Mongolia and other Chinese sites. Notable for a “waist” on the first lower molar and anterior cuspids on the lower premolars; the back teeth show a pattern similar to bone-crushing predators.
- Gobicyon serbiae: European member from Serbia; very similar to G. macrognathus but lacks some anterior cusp traits; its p4 and m1 enamel margins are nearly straight.
- Gobicyon yei: Primitive species from Ningxia, China, with a button-like third upper molar (M3) and a large second upper molar (M2); retains some traits seen in earlier Haplocyoninae.
- Gobicyon zhegalloi: Largest known species, from Mongolia and Xinjiang; has a larger second lower molar and fourth premolar; the m1 is unusually arranged, suggesting strong bone-cracking ability.
- Gobicyon acutus: The youngest species, known from two skulls at Yadang, Gansu; shows sexual dimorphism; p4 is robust and the first upper molar (M1) is enlarged, indicating a forward-shift in crushing power to the front teeth.

Size and ecology
- Size estimates suggest G. serbiae around 109 kg and other individuals possibly up to about 160 kg, but these figures are uncertain because they are based mostly on skulls.
- Gobicyon likely hunted large prey and used its strong premolars and first molars to crush bones, a trait convergent with hyenas.
- Postcranial remains are rare, but some limb bones hint at running abilities.
- Its closest known relative is Aktaucyon from Kazakhstan, and together they may represent an early branch of Haplocyoninae.

In summary, Gobicyon was a big, bone-crushing predator of the Middle Miocene in Asia and Europe, distinguished by its strong front teeth and unique jaw features, and it helps show how some amphicyonids evolved toward specialized biting across different regions.