Asiavorator
| Asiavorator Temporal range:
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|---|---|
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| Holotype limb bones ofA. gracilis | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Suborder: | Feliformia |
| Genus: | †Asiavorator Spassov & Lange-Badré, 1995 |
| Species: | †A. gracilis
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| Binomial name | |
| †Asiavorator gracilis Matthew & Granger, 1924
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| Synonyms | |
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List
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Asiavorator(meaning "Asian devourer" ) is an extinctgenusofcivet-like carnivoran belonging in the familyStenoplesictidae.It was endemic toAsiaand lived during theEoceneandOligoceneepochs.[1]
The teeth ofAsiavoratorsuggest that it wasomnivorousor more precisely, ranged fromhypercarnivoroustomesocarnivorous.[2][3]
Taxonomic history
[edit]The first remains ofAsiavoratorto be found were collected in the 1922 field season of the Central Asiatic Expeditions near the Loh campsite inÖvörkhangai Province,Mongolia. This locality is part of theHsanda Gol Formation.The specimens, designatedAMNH19123,included limb bones and lower teeth.MatthewandGranger(1924) described AMNH 19123 as the type specimen of a new carnivoran species they namedPalaeoprionodongracilis.[4]
The genusAsiavoratorwas erected by Spassov and Lange-Badré in 1995 as a monotypic genus for their new speciesA. altidens,with the type specimen ofA. altidensbeing amandible(FM 487-95) from the Hsanda Gol Formation.[5]Dashzeveg (1996) described a new species of stenoplesictid,Stenoplesictissimplex,based on a mandible (PSS 27-25) from theErgilin Dzo Formationof Mongolia.[6]In 1998, Hunt reassignedS. simplexto the genusShandgolictis,renaming itShandgolictis simplexand assigning it toAeluroidea.[7]
Later authors found thatAsiavorator altidensandPalaeoprionodon gracilisweresynonymousand represent a distinct genus, thus the two were synonymized asAsiavorator gracilis,retaining thespecific nameof the latter and thegeneric nameof the former. A re-examination by Egiet al.(2016) found that the tooth measurements of PSS 27-25 are not notably different from those of AMNH 19123, thus concluding thatStenoplesictis simplexandShandgolictis simplexarejunior synonymsofAsiavorator gracilis.Currently,A. gracilisis the only accepted species in the genus.[8]
Description
[edit]Using the carnivoranregressionon the specimen PSS 21-25,Asiavoratorhas been estimated to have a body mass of 3.6 to 5.6 kg. This is larger thanAlagtsavbaatar,a feliform known to have beensympatricwithAsiavorator,whose body mass has been estimated at 2.6 to 3.6 kg.[8]
Skull and teeth
[edit]
Like many other carnivorous mammals,Asiavoratorhas long and sharp-pointedcanine teeth,presumably used in killing prey. The upper and lower canines were approximately equal in length. Thecarnassialresembles that of a cat, being compressed and possessing a vestigial heel and reducedmetaconid.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 theprotoconidand paraconid, while the well-developed metaconid is placed against the internal posterior side of the protoconid. The base of the crown has acingulumon the external side. The second molar isbunodont,and possesses two roots and a flattenedtrigonidof three low cusps and a trenchant heel. The fourthpremolaris large and compressed, similar to the condition seen in domestic cats.[4][6]
Asiavoratorhad a well-developedmassetericfossa and a thinmandible.The mandibular corpus has a prominent lower edge below the molars. Below the first molar, themandibular ramusof the specimen PSS 27-25 measures 13.4 mm in height and 5.6 mm in width.[6]
Limbs
[edit]The limb bones ofAsiavoratorwere slender and long. At itsdistalend, thehumerusexpanded transversely with a strong epicondylar bridge. Theulnawas wide, and at theproximalhalf of the shaft it was flattened, whereas the distal half was triangular, though significantly less so than the slenderradiusin sectional area.Asiavoratorhad long and slender metatarsals, and thefirst metatarsal bonewas vestigial or absent. Thecalcaneumlacks a fibular facet. Thetalus bonepossessed deep and narrow trochlea, with a well-developed inner crest.[4]
Classification
[edit]In the original description of the holotype, Matthew and Granger (1924) assigned the species to the genusPalaeoprionodonasP. 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,Stenoplesictissimplex,by Dashzeveg (1996). The author placedS. simplexin the familyViverridaefollowing Hunt (1989), which listed the Stenoplesictinae as a probable subfamily of viverrids.[6][9]This subfamily would later be elevated to family level and renamedStenoplesictidae.The placement ofS. simplexin the genusStenoplesictiswas 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" gracilisand"Stenoplesictis" simplexwere very similar, and that this species likely belonged in the same lineage as"Stenoplesictis" indigenus(later renamedAlagtsavbaatarindigenus).[10]
Spassov and Lange-Badré (1995) did not assignAsiavoratorto any family in their description of the genus, placing it asFeliformiaincertae sedis.[5]Egi et al. (2016) made the same taxonomic placement for the genus, though they do state that the Mongolian small feliforms (Asiavorator,AlagtsavbaatarandShandgolictis) appear to form amonophyleticclade relative to the European generaStenoplesictis,PalaeoprionodonandHaplogale,which independently evolved hypercarnivory. They state this clade is a sister taxon to the extantFeliformiaexcluding theNandiniidae.[8]
Paleoecology
[edit]The oldest known fossils ofAsiavoratororiginate from thelate Eocene-agedErgilin Dzo Formationof Mongolia, suggesting the genus first evolved during theErgilianage. Sedimentary analyses suggest the Ergilin Dzo Formation was afloodplainenvironment with abraided streamnetwork formed by fluvial systems.[11]In this environment,sympatricpredators included the nimravidsNimravusandEofelis,the entelodontidEntelodon,and the related stenoplesictidAlagtsavbaatar.[8][12]
Most known specimens ofAsiavoratorwere found in theHsanda Gol Formation,which is dated to around 33.4 to 31 million years ago (early Oligocene). This formation is believed to have been deposited in an open,semi-aridsteppeenvironment withplaya lakesandephemeral rivers.[13]Many types of small mammals would have coexisted withAsiavoratorin this habitat, such as severalrodentspecies, the lagomorphDesmatolagusand the erinaceidPalaeoscaptor.[14][15]Sympatric predators included several species ofHyaenodon,the feliformsShandgolictis,NimravusandPalaeogale,the amphicynodontidsAmphicynodonandAmphicticeps,and the didymoconidsDidymoconusandErgilictis.[16]Herbivorous mammals were also present, such as the gelocidPseudogelocus,the largest of these being the hornless rhinocerotoidParaceratheriumtransouralicum.[17][18]
References
[edit]- ^Paleobiology Database:Asiavoratorbasic info.
- ^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.
- ^abcdMatthew, William Diller; Granger, Walter (1924)."New Carnivora from the Tertiary of Mongolia".American Museum Novitates(104).hdl:2246/3213.
- ^abSpassov, Nikolay; Lange-Badré, B. (1995)."Asiavorator altidensgen et sp. nov., un mammifere carnivore nouveau de l'Oligocene superieur de Mongolie ".Annales de Paléontologie(in French).81(3): 109–123.
- ^abcdDashzėvėg, Dėmbėrėliĭn; Akademi, Mongolyn Shinzhlėkh Ukhaany (1996)."Some carnivorous mammals from the Paleogene of the eastern Gobi Desert, Mongolia, and the application of Oligocene carnivores to stratigraphic correlation".American Museum Novitates(3179).
- ^Hunt, R. M. (1998). "Evolution of the aeluroid Carnivora: diversity of the earliest aeluroids from Eurasia (Quercy, Hsanda-Gol) and the origin of felids".American Museum Novitates(3252): 1–65.
- ^abcdEgi, Naoko; Tsubamoto, Takehisa; Saneyoshi, Mototaka; Tsogtbaatar, Khishigjav; Watabe, Mahito; Mainbayar, Buuvei; Chinzorig, Tsogtbaatar; Khatanbaatar, Purevdorg (2016-02-17)."Taxonomic revisions on nimravids and small feliforms (Mammalia, Carnivora) from the Upper Eocene of Mongolia".Historical Biology.28(1–2): 105–119.Bibcode:2016HBio...28..105E.doi:10.1080/08912963.2015.1012508.ISSN0891-2963.S2CID86239933.
- ^Hunt, Robert (1989-01-01)."Evolution of the Aeluroid Carnivora: Significance of the Ventral Promontorial Process of the Petrosal, and the Origin of Basicranial Patterns in the Living Families".Papers in the Earth and Atmospheric Sciences.
- ^Peigné, Stéphane; De Bonis, Louis (1999-09-14)."The genusStenoplesictisFilhol (Mammalia, Carnivora) from the Oligocene deposits of the Phosphorites of Quercy, France ".Journal of Vertebrate Paleontology.19(3): 566–575.Bibcode:1999JVPal..19..566P.doi:10.1080/02724634.1999.10011165.ISSN0272-4634.
- ^Watabe, Mahito (2010-03-31)."Lithostratigraphic and sedimentological analysis of the upper Eocene Ergilin Dzo Formation of Ergilin Dzo locality, Mongolia".Hayashibara Museum of Natural Sciences Research Bulletin.3:149–153.
- ^Watabe, Mahito (2013-11-29)."New specimens ofEntelodon gobiensis(Mammalia; Artiodactyla; Entelodontidae) from the Eocene Ergilin Dzo Formation, Mongolia ".Bull. Res. Inst. Nat. Sci., Okayama Univ. Of Sci.(39): 37–41.
- ^Richoz, Sylvain; Baldermann, Andre; Frauwallner, Andreas; Harzhauser, Mathias; Daxner-Höck, Gudrun; Klammer, Dietmar; Piller, Werner E. (March 2017)."Geochemistry and mineralogy of the Oligo-Miocene sediments of the Valley of Lakes, Mongolia".Palaeobiodiversity and Palaeoenvironments.97(1): 233–258.Bibcode:2017PdPe...97..233R.doi:10.1007/s12549-016-0268-6.ISSN1867-1594.PMC5367698.PMID28450967.
- ^Matthew, William Diller; Granger, Walter (1923)."Nine new rodents from the Oligocene of Mongolia".American Museum Novitates(102).hdl:2246/3214.
- ^Matthew, William Diller; Granger, Walter; Expeditions (1921-1930), Central Asiatic (1924)."New insectivores and ruminants from the Tertiary of Mongolia, with remarks on the correlation".American Museum Novitates(105).hdl:2246/3212.
{{cite journal}}:CS1 maint: numeric names: authors list (link) - ^Morlo, Michael; Nagel, Doris (2006)."The carnivore guild of the Taatsiin Gol area: Hyaenodontidae (Creodonta), Carnivora, and Didymoconida from the Oligocene of Central Mongolia".Annalen des Naturhistorischen Museums in Wien. Serie A für Mineralogie und Petrographie, Geologie und Paläontologie, Anthropologie und Prähistorie.108:217–231.ISSN0255-0091.
- ^Vislobokova, Inesa; Daxner-Höck, Gudrun (2001)."Oligocene - Early Miocene Ruminants from the Valley of Lakes (Central Mongolia)".Annalen des Naturhistorischen Museums in Wien. Serie A für Mineralogie und Petrographie, Geologie und Paläontologie, Anthropologie und Prähistorie.103:213–235.ISSN0255-0091.
- ^Osborn, Henry Fairfield; Berkey, Charles Peter (1923)."Baluchitherium grangeri,a giant hornless rhinoceros from Mongolia ".American Museum Novitates(78).hdl:2246/3262.