''Asiavorator'' (meaning "Asian devourer") is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

civet A civet () is a small, lean, mostly nocturnal mammal native to tropical Asia and Africa, especially the tropical forests. The term ''civet'' applies to over a dozen different species, mostly from the family Viverridae. Most of the species's div ...

-like carnivoran belonging in the family

Stenoplesictidae Stenoplesictidae is the name of a polyphyletic family of extinct civet-like feliforms Feliformia is a suborder within the order Carnivora consisting of "cat-like" carnivorans, including Felidae, cats (large and small), hyenas, mongooses, viver ...

. It was endemic to

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

and lived during the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

and

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

epochs. The teeth of ''Asiavorator'' suggest that it was

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

or more precisely, ranged from

hypercarnivorous A hypercarnivore is an animal that has a diet that is more than 70% meat, either via active predation or by scavenging. The remaining non-meat diet may consist of non-animal foods such as fungi, fruits or other plant material. Some extant example ...

to mesocarnivorous.

Taxonomic history

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 Övörkhangai (; " South Khangai") is one of the 21 aimags (provinces) of Mongolia. Its capital is Arvaikheer. The Shankh Monastery, one of the oldest and most important monasteries, is located in this province, as well as Erdene Zuu monast ...

, Mongolia. This locality is part of the Hsanda Gol Formation. The specimens, designated AMNH 19123, 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''. 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 In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

(FM 487-95) from the Hsanda Gol Formation. Dashzeveg (1996) described a new species of stenoplesictid, '' Stenoplesictis simplex'', based on a mandible (PSS 27-25) from the Ergilin Dzo Formation of Mongolia. In 1998, Hunt reassigned ''S. simplex'' to the genus '' Shandgolictis'', renaming it ''Shandgolictis simplex'' and assigning it to

Aeluroidea Aeluroidea, Ailuroidea, or Feloidea is the name of a taxon (infraorder or superfamily) comprising cat-like Carnivora. More specifically the taxon comprises:Feliformia, Pan-Feliformia. In: R. L. Carroll. 1988. Vertebrate Paleontology and Evoluti ...

. Later authors found that ''Asiavorator altidens'' and ''Palaeoprionodon gracilis'' were

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

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 synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

s of ''Asiavorator gracilis''. Currently, ''A. gracilis'' is the only accepted species in the genus.

Description

Using the carnivoran regression on the specimen PSS 21-25, ''Asiavorator'' has been estimated to have a body mass of 3.6 to 5.6 kg. This is larger than '' Alagtsavbaatar'', a feliform known to have been

sympatric In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

with ''Asiavorator'', whose body mass has been estimated at 2.6 to 3.6 kg.

Skull and teeth

Like many other carnivorous mammals, ''Asiavorator'' has long and sharp-pointed

canine teeth In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, eye teeth, vampire teeth, or fangs, are the relatively long, pointed teeth. In the context of the upper jaw, they are also known as '' fangs''. They can appear more fl ...

, presumably used in killing prey. The upper and lower canines were approximately equal in length. The

carnassial Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...

resembles that of a cat, being compressed and possessing a vestigial heel and reduced

metaconid Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...

. The first upper molar is very elongated, measuring 10 mm long and 4.5 mm wide in the specimen PSS 27-25. An obtuse angle is formed by the shearing edges of the

protoconid Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...

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 The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth ...

, and possesses two roots and a flattened

trigonid The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth ...

of three low cusps and a trenchant heel. The fourth

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

is large and compressed, similar to the condition seen in domestic cats. ''Asiavorator'' had a well-developed masseteric fossa and a thin

. 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 13.4 mm in height and 5.6 mm in width.

Limbs

The limb bones of ''Asiavorator'' were slender and long. At its

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

end, the

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

expanded transversely with a strong epicondylar bridge. The

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

was wide, and at the

proximal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

half of the shaft it was flattened, whereas the distal half was triangular, though significantly less so than the slender

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

in sectional area. ''Asiavorator'' had long and slender metatarsals, and the

first metatarsal bone The first metatarsal bone is the bone in the foot just behind the big toe. The first metatarsal bone is the shortest of the metatarsal bones and by far the thickest and strongest of them. Like the four other metatarsals, it can be divided into ...

was vestigial or absent. The

calcaneum In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel; : calcanei or calcanea) or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is t ...

lacks a fibular facet. The

talus bone The talus (; Latin for ankle or ankle bone; : tali), talus bone, astragalus (), or ankle bone is one of the group of Foot#Structure, foot bones known as the tarsus (skeleton), tarsus. The tarsus forms the lower part of the ankle joint. It transmit ...

possessed deep and narrow trochlea, with a well-developed inner crest.

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. 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 Viverridae is a family (biology), family of small to medium-sized feliform mammals, comprising 14 genera with 33 species. This family was named and first described by John Edward Gray in 1821. Viverrids occur all over Africa, in southern Europe, ...

following Hunt (1989), which listed the Stenoplesictinae as a probable subfamily of viverrids. This subfamily would later be elevated to family level and renamed

. 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''). Spassov and Lange-Badré (1995) did not assign ''Asiavorator'' to any family in their description of the genus, placing it as

Feliformia Feliformia is a suborder within the order Carnivora consisting of "cat-like" carnivorans, including Felidae, cats (large and small), hyenas, mongooses, viverrids, and related taxa. Feliformia stands in contrast to the other suborder of Carnivora, ...

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

.'' 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 In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

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

excluding the Nandiniidae.

Paleoecology

The oldest known fossils of ''Asiavorator'' originate from the

late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

-aged Ergilin Dzo Formation of Mongolia, suggesting the genus first evolved during the Ergilian age. Sedimentary analyses suggest the Ergilin Dzo Formation was a

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high Discharge (hydrolog ...

environment with a

braided stream A braided river (also called braided channel or braided stream) consists of a network of river channels separated by small, often temporary, islands called '' braid bars'' or, in British English usage, '' aits'' or ''eyots''. Braided streams t ...

network formed by fluvial systems. In this environment,

predators included the nimravids '' Nimravus'' and '' Eofelis'', the entelodontid ''

Entelodon ''Entelodon'' (meaning 'complete teeth', from Ancient Greek ''entelēs'' 'complete' and ''odōn'' 'tooth', referring to its "complete" eutherian dentition), formerly called ''Elotherium'', is an extinct genus of entelodont artiodactyl endemic ...

'', and the related stenoplesictid '' Alagtsavbaatar''. Most known specimens of ''Asiavorator'' were found in the Hsanda Gol Formation, which is dated to around 33.4 to 31 million years ago (

early Oligocene The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded b ...

). This formation is believed to have been deposited in an open,

semi-arid A semi-arid climate, semi-desert climate, or steppe climate is a aridity, dry climate sub-type. It is located on regions that receive precipitation below Evapotranspiration#Potential evapotranspiration, potential evapotranspiration, but not as l ...

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the tropical and subtropica ...

environment with playa lakes and ephemeral rivers. Many types of small mammals would have coexisted with ''Asiavorator'' in this habitat, such as several

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

species, the lagomorph '' Desmatolagus'' and the erinaceid '' Palaeoscaptor''. Sympatric predators included several species of ''

Hyaenodon ''Hyaenodon'' ("hyena-tooth") is an Extinction (biology), extinct genus of Carnivore, carnivorous Placentalia, placental mammals from extinct tribe Hyaenodontini within extinct subfamily Hyaenodontinae (in extinct Family (biology), family Hyaenod ...

'', the feliforms '' Shandgolictis'', '' Nimravus'' and '' Palaeogale'', the amphicynodontids '' Amphicynodon'' and '' Amphicticeps'', and the didymoconids '' Didymoconus'' and '' Ergilictis''. Herbivorous mammals were also present, such as the gelocid '' Pseudogelocus'', the largest of these being the hornless rhinocerotoid ''Paraceratherium'' ''transouralicum''.

References

External links

{{Taxonbar, from=Q3605635 Viverrids Oligocene mammals of Asia Oligocene feliforms Monotypic prehistoric carnivoran genera