Amphicyon is an extinct genus of large carnivorans belonging to the family Amphicyonidae (known colloquially as "bear-dogs"), subfamily Amphicyoninae, from the Miocene epoch. Members of this family received their vernacular name for possessing bear-like and dog-like features. They ranged over North America, Eurasia, and Africa.
Taxonomy
In a note dated back to May 16, 1836, French geologist Alexandre Leymerie wrote a letter in April that he requested from French palaeontologist Édouard Lartet, which provided details of his exploits in palaeontological sites in the French department of Gers, in particular the commune Sansan. Lartet described his finds of fossil taxons that he found within the sites, including "Mastodonte" (species assigned to it were later reclassified to another mammutid Zygolophodon and the gomphothere Gomphotherium), "Dinotherium" (its species eventually reclassified as either Deinotherium or Prodeinotherium), "Rhinoceros" (reclassified as an aceratherine rhinocerotid Hoploaceratherium), and "Palaeotherium" (the referred equid species now known as belonging to an anchitherine Anchitherium). He also recalled finding fossil "deer" species of which he said that the largest ones were the size of extant deer in France while the smallest ones were the size of small antelope. The palaeontologist noted that the "peaceful ruminants" coexisted with a "formidable" large carnivore he provisionally named Amphicyon based on two half-jaws and bones that he sent to a museum. He described it as having unilobed incisors and compressed canines similar to raccoons but also a carnivorous molar and its first two tubercles conforming those to dogs. Lartet then stated that the genus's most distinct trait was the existence of a third tubercle at the upper jaw, which was not known in any other carnivore. The genus name may come from Ancient Greek ἀμφί (amphí), meaning "both", and κύων (kúon), meaning "dog", but Lartet did not define the genus's etymology.
Despite the initial status of the genus name Amphicyon as nonpermanent, French anatomist Henri Marie Ducrotay de Blainville, a peer who Lartet had regularly discussed his fossil findings with, had sketched mammal skeletons and fossils in 1841, where he recognized the 2 species "Amphicyon major" and "Amphicyon? minor." In 1851, Lartet reviewed the fossil carnivoran genera from Sansan. Among them were Amphicyon, in which it was reconfirmed as a carnivorous mammal the size of extant bears that was discovered in Sansan in 1835. He recalled that its single-lobed incisors and its canines of serrated ridges are similar to the raccoon while the molars were similar to that of a dog. He confirmed the fossil specimens along with the third tubercle in the upper jaw (of which he said that it only exists in the extant bat-eared fox (then known as "Canis megalotis")) as belonging to the species Amphicyon major. The palaeontologist described it as also having an anatomy of plantigrade locomotion similar to extant bears with few differences in form. Blainville was mentioned as speculating that it must have had a long and very strong tail. The species "Amphicyon minor" was reclassified as a separate genus Hemicyon, which he described as a carnivore larger than a European wolf that was closer in form to a dog than Amphicyon and had dentition similar to mustelids. He also described a newer genus Pseudocyon, which he misidentified as being digitigrade and described as being smaller than Amphicyon and coming closest to canids based on its dentition and bones. All three genera, Lartet said, had canines that retained finely serrated edges, implying that they were some of the top coexisting predators of the Miocene in modern-day France.
Species European species
Amphicyon astrei The oldest known species of the genus, A. astrei is known from the Early Miocene sites Gardouch and Paulhiac in France, which date to MN1 (or "Mammal Neogene 1" as part of the Mammal Neogene zones). The species was originally described by Kuss in 1962, however, he also noted that its features do not completely match any known genus, and later moved it to the genus Pseudocyon, as subspecies of P. sansanienis, and considered it to be ancestral to P. s. intermedius (which has since then been moved to the separate genus Crassidia). Ginsburg and Antunes later reassigned it to Amphicyon, which was followed by other authors, and suggested that it was ancestral to later species of the genus. Unlike later members of the genus, it did not possess enlarged posterior molars.
Amphicyon lactorensis This species was originally described by Astre on the basis of a single molar, from the French locality Le Mas d'Auvignon, which dates to MN4/5. Ginsburg referred more material from MN4-5 of France to this species, and assigned it to the subgenus Euroamphicyon. Its M2 is peculiar, as it is anteroposteriorly shortened but transversely elongated. Kuss synonymized it with A. depereti, which has since been moved to Ysengrinia, although later authors generally consider it to be a valid species of Amphicyon.
Amphicyon major A. major, which was named by De Blainville in 1841, is both the type species of the genus but also the best known, as various cranial and even postcranial remains have been discovered across Western and Central Europe as well as Turkey. It first appeared in MN4 and lasted until at least MN6. Amphicyonid remains from La Grive Saint-Alban, dating back to MN7/8, have also been assigned to this species. Others point out the differences between these fossils and the type material of A. major, suggesting that they may belong to a separate species. It is likely closely related to the geologically younger A. eppelsheimensis, A. gutmanni and A. pannonicus, the first two of which had previously been assigned to A. major as subspecies.
Amphicyon eppelsheimensis A mandible and a mandibular fragment belong to A. eppelsheimensis were originally discovered at the locality Eppelsheim in Germany, and described by Weitzel in 1930. Other remains have since been found at Gau-Weinheim, which is located in close proximity to Eppelsheim, and the Spanish Valles de Fuentidueña. All these localities date to MN9-10. The taxonomic status of this species is controversial, with Kuss and several other authors considering this taxon to be a subspecies or synonym of A. major. Later authors however suggest that the two species are distinct, with A. eppelsheimensis possibly being the last representative of the A. major lineage. Notably, the p4 is more strongly reduced than in A. major, and it is also slightly larger.
Amphicyon gutmanni A. gutmanni was described by Kittl in 1891 on the basis of a single, robust and low-crowned lower carnassial. Kuss considered it to be a subspecies of A. major, but Kretzoi argued for its validity, based on the contour of its talonid, and even erected the separate genus Hubacyon, with H. gutmanni as type species. Viranta followed his arguments for the distinction of this species, but did not consider Hubacyon to be a valid genus. The highest point of its hypoconid is located more posterior than in other members of this genus, and a line drawn from the posterolingual corner to the posterobuccal corner possesses a greater angle on the buccal side, due to the extended posterobuccal corner. Both of these features are similar to those seen in thaumastocyonines. Its type locality Mannersdorf, in Austria, is of uncertain age, but the presence of hipparionine horses shows that it is no older than MN9. Viranta also tentatively assigns molars from Kohfidisch, previously referred to cf. A. giganteus, to this species. As this locality dates to MN11, this would make it one of the youngest members of the family. This species is likely closely related to A. major.
Amphicyon pannonicus The molar of this species was discovered in the Danitzpuszta sandpit in Pécs, southern Hungary, and originally described by Kretzoi in 1985 as Hubacyon (Kanicyon) pannonicus. Some authors state that locality of where it was found has been considered to date to MN11-12, which would make it one of the youngest known amphicyonids, although its exact dating is unclear. However, the terrestrial assemblage of the sandpit generally points towards an Early Pannonian (Vallesian) age, as which is in agreement with Kretzoi's original description. This species is potentially hypercarnivorous, and only known from a single, fragmentary tooth, which is smaller, more slender and gracile than that of A. gutmanni, as well as considerably more brachydont. Just like A. gutmanni, it is considered to be closely related to A. major.
Amphicyon carnutense A. carnutense, known from the MN3 of France and possibly Czechia, is a large species with a confusing taxonomic history. The type material from Chilleurs-aux-Boiwas was originally described a subspecies of A. giganteus, A. g. carnutense, and considered ancestral to the nominal subspecies A. g. giganteus. The subspecies was discarded later on, but other authors considered A. carnutense distinct enough for it to be classified as a separate species. Adding to the confusion is the status of Megamphicyon, to which A. carnutense is referred, which is variously considered to be synonymous with Amphicyon, a subgenus of the former or a separate genus altogether. Furthermore, Amphicyon lathanicus, originally described in 2000 on basis of isolated teeth from Beilleaux à Hommes, France, which date to MN3, with further remains reported across France, is likely synonymous with A. carnutense.
Amphicyon giganteus A. giganteus was originally described by Schinz in 1825, and in 1965 Kuss erected the genus Megamphicyon for this species, based on differences in its dentition and size between it and A. major. Subsequent authors generally disregarded this assignment, with Ginsburg considering Megamphicyon a subgenus of Amphicyon. Siliceo et al. revived the genus in 2020, a classification that was followed by some authors. Others, however, reject the reclassification in favour of the older classification A. giganteus. A. giganteus was a widespread European species that lived during the late Burdigalian to late Seravallian, corresponding to the MN4-MN7/8. Most remains were found in Western Europe, although the youngest known record of the species is from Turkey, possibly suggesting the species survived in Anatolia after it had already gone extinct in Europe. Fossils from this species are also known from Bosnia and Herzegovina as well as the locality Arrisdrift in Namibia. It has also been referred to fossil specimens from Moghra in Egypt, but the referral of these fossils remains controversial. It has furthermore been reported from levels 5 to 6 of Pakistans lower Vihowa Formation. The age of these remains is between 19 and 18.5 Ma, with a molar from the base of the Potwar Plateau sequence extending its range in the Siwaliks to 17.9 Ma. An even younger fossil possibly referable to this species is a large humerus known from the base of the Manchar formation. It differs from A. major through its larger size, bigger premolars, shorter diastemata, a P4 that possesses a larger and lingually extended protocone and the presence of a paracone, that is very large and high paracone in comparison with its metacone, on its elongated M1. A. eibiswaldensis is generally considered to be a junior synonym of this species.
Amphicyon laugnacensis Originally described as subspecies of A. giganteus, A. laugnacensis was elevated to species level by Ginsburg in 1999. It is the oldest known member of the A. giganteus lineage, with both its type locality Laugnac and possible remains from Gérand-le-Puy and Grépiac dating to MN2. Its holotype is a maxilla, previously referred to A. astrei, possesses a parastyle and a more posteriorly located protocone.
Amphicyon olisiponensis