The Ergilin Dzo Formation (formerly known as the Ardyn Obo Formation), is a geologic formation in southeastern Mongolia. It preserves fossils of a wide variety of animals, which date back to the late Eocene epoch. The type fauna of the Ergilian Asian land mammal age is defined by the mammalian fossils of this formation.
Depositional environment Based on the presence of brontotheres and the abundance of herbivorous low-crowned mammals, the Ergilin Dzo Formation has been estimated to be humid and warm/hot with a relatively-closed area. However, the absence of primates and rarity of crocodyliforms (known from one specimen currently) in this formation may suggest the paleoenvironment had open areas and was more arid than similarly aged faunal assemblages from elsewhere in Eurasia. Sedimentary analyses suggest the Ergilin Dzo Formation was a floodplain environment with a braided stream network formed by fluvial systems.
Fossil content In their review of the vertebrate fauna of the formation, Tsubamoto et al. (2022) found that 77 genera and 104 species of vertebrate have been reported from the Ergilin Dzo Formation, representing 22 orders and 49 families. Fossils of mammals, reptiles (including birds), fish and amphibians have all been recovered from the formation since the early 20th Century.
Mammals 81 mammal species have been found in the Ergilin Dzo Formation, with perissodactyls being the most diverse group (33 species reported). Ruminant artiodactyls, rhinocerotoids and brontotheres are the most abundant groups in terms of collected specimen numbers.
Artiodactyls Artiodactyls reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesAnthracotheriidae indet.IndeterminateErgilin Dzo locality.Left astragalus.An anthracothere.cf. Bothriodoncf. B. sp.Ergilin Dzo & Khoer Dhan localities.Jaw & limb elements.An anthracothere.BrachyhyopsB. trofimoviKhoer Dzhan locality.Jaw elements.An entelodontid.B. sp.Ergilin Dzo locality.Right maxilla fragment.An entelodontid.EntelodonE. gobiensisKhoer Dzhan & Ergilin Dzo localities.An entelodontid.EumeryxE. sp.A deer.GobiomeryxG. dubiusA leptomerycid.LophiomeryxL. angaraeA lophiomerycid.L. sp.A lophiomerycid.MiomeryxM. altaicusA leptomerycid.M. sp.A leptomerycid.PraetragulusP. electusKhoer Dzhan locality.Numerous jaw & limb elements.A hypertragulid.P. gobiaeErgilin Dzo locality.Jaw elements.A hypertragulid.
Cimolestans Cimolestans reported from the Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesGobiopithecusG. khanKhoer Dzhan locality.Ergilin Member.Mandibles.A pantolestid.
Didymoconids Didymoconids reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesArdynictisA. furunculusSkull & jaws.ErgilictisE. reshetoviErgilin Dzo locality.Jaw elements.
Eulipotyphlans Eulipotyphlans reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesAmphechinusA. sp.Ergilin Dzo locality.Sevkhul Member.Left dentary fragment.A hedgehog.Ictopidium?I.? sp.A changlelestid.OligochenusO. grandisErgilin Dzo locality.Sevkhul Member.Right dentary fragment.A gymnure.Palaeoscaptor?P.? sp.A hedgehog.Soricinae indet.IndeterminateA shrew.Tupaiodontinae indet.IndeterminateErgilin Dzo locality.Ergilin Member.Premolar.A changlelestid.
Ferae Ferae reported from the Ergolin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesAlagtsavbaatarA. indigenusAlag Tsav & Khoer Dzhan localities.Jaw & limb elements.A small feliform.Amphicyonidae indet.IndeterminateErgilin Dzo locality.Tooth.A bear-dog.AsiavoratorA. gracilisErgilin Dzo locality.Right mandible fragment.A small feliform.EofelisE. sp.Khoer Dzhan locality.Jaw elements.A nimravid.HyaenodonH. chunkhtensisKhoer Dzhan locality.Left mandibular corpus.A hyaenodont.H. eminusKhoer Dzhan & Ergilin Dzo localities.Jaw elements.A hyaenodont.H. gigasKhoer Dzhan locality.A hyaenodont.H. incertusKhoer Dzhan & Ergilin Dzo localities.A hyaenodont.H. mongoliensisKhoer Dzhan & Ergilin Dzo localities.A hyaenodont.H. pervagusKhoer Dzhan & Ergilin Dzo localities.A hyaenodont.H. pumilusMandibular ramus.A hyaenodont.NimravusN. mongoliensisKhoer Dzhan locality.Jaw & limb elements.A nimravid.Proviverrinae indet.IndeterminateKhoer Dzhan locality.Tooth.A hyaenodont.
Gliriformes Gliriformes reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesArdynomysA. olseniLower jaw.A rodent.A. silentiumisA rodent.A. sp.A rodent.DesmatolagusD. ardynenseA lagomorph.D. gobiensisA lagomorph.D. robustusLower jaws.A lagomorph.EucricetodonE. sp.A rodent.Lagomorpha indet.IndeterminateA lagomorph.ZofiagaleZ. ergilensisErgilin Dzo locality.Right dentary.An anagalid.
Mesonychians Mesonychians reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesMetahapalodectesM. sp.A hapalodectid.MongolestesM. hadrodensA mesonychid.
Perissodactyls Perissodactyls reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes Imagescf. Allaceropscf. A. sp.Khoer Dzhan.Jaw elements.An eggysodontid."Amynodon"A. sp.An amynodont. Amynodon is generally treated as an exclusively North American genus; Asian fossils attributed to Amynodon are in need of reexamination.A. lunanensisAn amynodont. Classified as a species of Amynodontopsis by Tsubamoto et al. (2022).ArdyniaA. praecoxKhoer Dzhan.Sevkhul & Ergilin members.Jaw elements.A hyracodontid.A. sp.Khoer Dzhan.Sevkhul & Ergilin members.Jaw fragments.A hyracodontid.ArmaniaA. asianaKhoer Dzhan & Ergilin Dzo.Sevkhul & Ergilin Members.Jaw elements.An amynodont or hyracodontid.Brontotheriidae indet.IndeterminateA brontothere.CadurcodonC. ardynensisAn amynodont.C. sp.An amynodont.cf. Deperetellacf. D. sp.A deperetellid.EmbolotheriumE. andrewsiSkull.A brontothere.E. grangeriKhoer Dzhan.Partial skull.A brontothere.E. sp.A brontothere.EomoropusE. sp.An eomoropid.EubrontotheriumE. clarnoensisErgilin Dzo.Partial skeleton.A brontothere.HypsamynodonH. progressusAn amynodont.JuxiaJ. borissiakiErgilin Dzo locality.Ergilin Member.Jaws & teeth.A paraceratheriid.Paraceratheriidae indet.IndeterminateKhoer Dzhan.Ergilin Member.Teeth.Initially reported as Urtinotherium (or Paraceratherium) sp.ParacolodonP. inceptusA helaletid.P. sp.A helaletid.ProhyracodonP. meridionalisKhoer Dzhan.Sevkhul Member.Jaw elements.A hyracodontid.P. obrutschewiA hyracodontid.?P. parvumKhoer Dzhan.Zangut-Sevkhul member.Jaw elements.A hyracodontid.Protitan?"P." robustumA brontothere, variously treated as a species of Epimanteoceras, a synonym of Protitan grangeri, or a possible synonym of Nasamplus progressus.ProtembolotheriumP. efremoviErgilin Dzo.Skull elements.A brontothere.RonzotheriumR. brevirostrisA rhinoceros.R. orientaleErgilin Dzo, Bayan Tsav ravine & Khoer Dzhan.Ergilin Member.Jaw elements.A rhinoceros.R. sp.Khoer Dzhan.Ergilin Member.Fragment of mandibular ramus.A rhinoceros.SchizotheriumS. avitumA chalicothere.SharamynodonS. mongoliensisAn amynodont.TeleolophusT. magnusA deperetellid.UrtinotheriumU. parvumA paraceratheriid.cf. Zaisanamynodoncf. Z. sp.An amynodont.
Reptiles Reptiles are represented by 20 known species in the formation, with 11 of these being birds.
Birds Birds reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesAccipitridae indet.IndeterminateKhoer Dzhan.Leg bones.An accipitrid.Anatidae indet.IndeterminateKhoer Dzhan.An anatid.Ardeidae indet.IndeterminateKhoer Dzhan.A heron.Cygninae indet.IndeterminateKhoer Dzhan.A swan.EogrusE. sp.Ergilin Dzo.An eogruid.ErgilornisE. minorErgilin Dzo.An eogruid.E. rapidusErgilin Dzo.An eogruid.E. sp.An eogruid.GobicathartesG. prodigialipesErgilin Dzo.A New World vultureLari indet.IndeterminateKhoer Dzhan.Skull fragment.A shorebird.Rallidae indet.IndeterminateKhoer Dzhan.A rail.SonogrusS. gregalisAn eogruid.
Crocodyliforms Crocodyliforms reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesCrocodyliformes indet.IndeterminateErgilin Dzo.Tooth.
Squamates Squamates reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesAgamidae indet.IndeterminateAn agamid lizard.Lacertilia indet.IndeterminateA lizard.
Turtles Turtles reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesChrysemysC. sp.Emydidae gen. et. sp. indet.IndeterminateA terrapin.ErgilemysE. insolitusA tortoise.?Melanochelys?M. elongataPlatysternidae gen. et. sp. indet.IndeterminateTrionychidae gen. et. sp. indet.IndeterminateA softshell turtle.
Amphibians Amphibians reported from the Ergilin Dzo Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesUrodela gen. et. sp. indet.IndeterminateA salamander.
Fish Fish reported from the Formation Genus Species Presence Stratigraphic memberMaterial Notes ImagesAmiaA. sp.A bowfin.ParasilurusP. sp.A catfish.
See also
List of fossiliferous stratigraphic units
References