Asiavorator (meaning "Asian devourer") is an extinct genus of civet-like carnivoran belonging in the family Stenoplesictidae. It was endemic to Asia and lived during the Eocene and Oligocene epochs.[1]
The first remains of Asiavorator to be found were collected in the 1922 field season of the Central Asiatic Expeditions near the Loh campsite in Övörkhangai Province, Mongolia. This locality is part of the Hsanda Gol Formation. The specimens, designated AMNH19123, included limb bones and lower teeth. Matthew and Granger (1924) described AMNH 19123 as the type specimen of a new carnivoran species they named Palaeoprionodon gracilis.[4]
The genus Asiavorator was erected by Spassov and Lange-Badré in 1995 as a monotypic genus for their new species A. altidens, with the type specimen of A. altidens being a mandible (FM 487-95) from the Hsanda Gol Formation.[5] Dashzeveg (1996) described a new species of stenoplesictid, Stenoplesictis simplex, based on a mandible (PSS 27-25) from the Ergilin Dzo Formation of Mongolia.[6] In 1998, Hunt reassigned S. simplex to the genus Shandgolictis, renaming it Shandgolictis simplex and assigning it to Aeluroidea.[7]
Later authors found that Asiavorator altidens and Palaeoprionodon gracilis were synonymous and represent a distinct genus, thus the two were synonymized as Asiavorator gracilis, retaining the specific name of the latter and the generic name of the former. A re-examination by Egi et al. (2016) found that the tooth measurements of PSS 27-25 are not notably different from those of AMNH 19123, thus concluding that Stenoplesictis simplex and Shandgolictis simplex are junior synonyms of Asiavorator gracilis. Currently, A. gracilis is the only accepted species in the genus.[8]
Description
Using the carnivoran regression on the specimen PSS 21-25, Asiavorator has been estimated to have a body mass of 3.6 to 5.6kg. This is larger than Alagtsavbaatar, a feliform known to have been sympatric with Asiavorator, whose body mass has been estimated at 2.6 to 3.6kg.[8]
Skull and teeth
Top and side views of the teeth in the specimen AMNH 19123
Like many other carnivorous mammals, Asiavorator has long and sharp-pointed canine teeth, presumably used in killing prey. The upper and lower canines were approximately equal in length. The carnassial resembles that of a cat, being compressed and possessing a vestigial heel and reduced metaconid. The first upper molar is very elongated, measuring 10mm long and 4.5mm wide in the specimen PSS 27-25. An obtuse angle is formed by the shearing edges of the protoconid and paraconid, while the well-developed metaconid is placed against the internal posterior side of the protoconid. The base of the crown has a cingulum on the external side. The second molar is bunodont, and possesses two roots and a flattened trigonid of three low cusps and a trenchant heel. The fourth premolar is large and compressed, similar to the condition seen in domestic cats.[4][6]
Asiavorator had a well-developed masseteric fossa and a thin mandible. The mandibular corpus has a prominent lower edge below the molars. Below the first molar, the mandibular ramus of the specimen PSS 27-25 measures 13.4mm in height and 5.6mm in width.[6]
Limbs
The limb bones of Asiavorator were slender and long. At its distal end, the humerus expanded transversely with a strong epicondylar bridge. The ulna was wide, and at the proximal half of the shaft it was flattened, whereas the distal half was triangular, though significantly less so than the slender radius in sectional area. Asiavorator had long and slender metatarsals, and the first metatarsal bone was vestigial or absent. The calcaneum lacks a fibular facet. The talus bone possessed deep and narrow trochlea, with a well-developed inner crest.[4]
Classification
In the original description of the holotype, Matthew and Granger (1924) assigned the species to the genus Palaeoprionodon as P. gracilis, referring it to the European genus based on similarities in the dentition and proportions of the limbs, though they did clarify that this referral is provisional until the dentition is better known.[4]
The referred mandible PSS 27-25 was described as a new species, Stenoplesictis simplex, by Dashzeveg (1996). The author placed S. simplex in the family Viverridae following Hunt (1989), which listed the Stenoplesictinae as a probable subfamily of viverrids.[6][9] This subfamily would later be elevated to family level and renamed Stenoplesictidae. The placement of S. simplex in the genus Stenoplesictis was refuted by Peigné and de Bonis (1999) based on the dentition, though they did not assign the species to another genus. However, they did note that the type specimens of "Palaeoprionodon" gracilis and "Stenoplesictis" simplex were very similar, and that this species likely belonged in the same lineage as "Stenoplesictis" indigenus (later renamed Alagtsavbaatar indigenus).[10]
Spassov and Lange-Badré (1995) did not assign Asiavorator to any family in their description of the genus, placing it as Feliformiaincertae sedis.[5] Egi et al. (2016) made the same taxonomic placement for the genus, though they do state that the Mongolian small feliforms (Asiavorator, Alagtsavbaatar and Shandgolictis) appear to form a monophyletic clade relative to the European genera Stenoplesictis, Palaeoprionodon and Haplogale, which independently evolved hypercarnivory. They state this clade is a sister taxon to the extant Feliformia excluding the Nandiniidae.[8]
↑Lillegraven, J. A. (1979). "Reproduction in Mesozoic mammals". In J. A. Lillegraven; Z. Kielan-Jaworowska; W. A. Clemens (eds.). Mesozoic Mammals: The First Two-Thirds of Mammalian History. Berkeley: University of California Press. pp.259–276.
↑Nowak, R. M. (1999). Walker's Mammals of the World, Sixth Edition. Vol.I. pp.1–836.
