Nemegt Formation
Geological formation in Mongolia
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The Nemegt Formation (also known as Nemegtskaya Svita) is a geological formation in the Gobi Desert of Mongolia, dating to the Late Cretaceous. The formation consists of river channel sediments and contains fossils of fish, turtles, crocodilians, and a diverse fauna of dinosaurs, including birds.
| Nemegt Formation | |
|---|---|
| Stratigraphic range: Possibly also late Campanian | |
Nemegt, the type locality of the Nemegt Formation | |
| Type | Geological formation |
| Sub-units | Lower, Middle and Upper units |
| Underlies | Alluvium |
| Overlies | Baruungoyot Formation |
| Thickness | Over 235 m (771 ft) |
| Lithology | |
| Primary | Shale, sandstone |
| Other | Mudstone, conglomerate |
| Location | |
| Coordinates | 43.5°N 101.0°E |
| Approximate paleocoordinates | 40.8°N 90.2°E |
| Region | Bayankhongor Aimag, Omnogov, Ovorkhangai |
| Country | Mongolia |
| Extent | Gobi Desert |
  Nemegt Formation (Mongolia) | |
Description
The Nemegt Formation is composed of mudstones and sandstones that were deposited by ancient lakes, streams, and flood plains. The Altan Uul locality was described by Michael Novacek as "a canyon carved out of a very rich series of sedimentary rocks" with "steep cliffs and narrow washes". The climate associated with it was wetter than when preceding formations were deposited; there seems to have existed at least some degree of forest cover as indicated by petrified fossil trunks. When examined, the rock facies of the upper section consist of braided meanders, and oxbow lakes. Alteration of sediment grades indicates frequent hydrodynamic condition changes (seasonal rain). Siltstone pellets indicate desiccation at the channel margins in river low-stand periods. Bank erosion features would form through river channel migration. Generally rivers consisted of low flow regimes with sporadic upper flow regimes indicated by exotic pebbles. The lower sections of the formation may represent lacustrine or palustrine deposition.[1] A study of oxygen-18 isotopes from theropod teeth show seasonal patterns similar to present day continental climates. Mean annual temperatures are estimated to be around 7.6 °C (45.7 °F) with seasonal precipitation patterns compared to meteorological data from Shijiazhuang, China; suggesting a monsoonal, cold semi-arid climate.[2] That same study indicated that due to the greenhouse conditions of the Cretaceous, the East Asian monsoon was strong enough to reach into Mongolia. The Nemegt environment was dominated by araucarian conifers,[2] but it also supported a diverse array of other plants, including ginkgos and a wide variety of angiosperms—ranging from plane trees (sycamores) to duckweeds.[3] The groundcover included quillwort like plants as well as sedges (members of the group Cyperaceae).[3] Grass is also known from the formation, and as in the Laramie Formation of North America,[4] reed grasses (primarily Phragmites) were present.[5] The area also supported Bald Cypress.[5] The area probably resembled the modern day Okavango Delta in Botswana.[6]
Stratigraphy
The most recent stratigraphy divides the Nemegt Formation into three informal members. The lower member is dominated by fluvial deposits, while middle and upper members consist of alluvial plain, paludal, lacustrine, and fluvial deposits. The colour of the sediments is usually light grey to tan in colour in comparison to the typically red colour of the underlying Baruungoyot Formation.[7] It overlies and sometimes interfingers with the Baruungoyot Formation. Interfingering has been noted at the stratotype (Red Walls) and Hermiin Tsav.[7] There has been no absolute dating of the Nemegt Formation. Historically the Nemegt has been considered late Campanian to Maastrichtian, based on comparisons of fossils present, but no exact dating has been performed. U-Pb dating from teeth of Tarbosaurus suggested that the deposition of the middle Nemegt Formation happened before 66.7 ± 2.5 Ma, during the Maastrichtian age, though whether the depositional age of the formation dates back to the late Campanian remains unresolved.[8]
While it has been generally assumed that the Djadochta, Baruungoyot, and Nemegt formations were layered in succession, some geological analysis suggested interfingering rather than superposition of these features. Thus these formations could represent different parts of a single interconnected ecosystem, with the Djadochta reflecting arid dune habitats dominated by small animals, the Baruungoyot representing transitional semi-arid zones, and the Nemegt capturing wetter river plains that supported large dinosaurs.[9]
Paleobiota of the Nemegt Formation
Stratigraphic positions are based on Eberth (2018) who correlated localities to their approximate position within the formation.[7]
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Flora
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image | |
|---|---|---|---|---|---|---|---|
| Araucariaceae[2] | Indeterminate | Altan Ula II | "Petrified wood and trunks" | Araucarian conifer, probably the dominant flora of the formation.[2] |  | ||
| Arundo | A. sp. | Nogon Tsav | "Leaf impressions."[5] | Cane Grass. |  | ||
| Carpinus | C. altanensis | Atlan Uul | "Fruits."[5] | A Hornbeam birch |
| ||
| Cyperaceae indet. | Indeterminate | Ulaan Bulag | "Scattered stem and leaf impressions."[10] | A grass-like monocot. | _Hassk._(AM_AK330056-2).jpg) | ||
| Ginkgo | G. altanensis | Altan Uul | "Leaf impressions."[5] | Ginkgophyte. |  | ||
| G. sp. | Altan Uul | "Leaf impressions."[3] | Ginkgophyte. | ||||
| Lemna | L. chushuensis | Tsagan Khushu | "Fruit."[5] | Duckweed. |  | ||
| Lemnaceae indet. | Indeterminate | Tsagan Khushu, Ulaan Bulag | "Fruits."[11] | Duckweed. | |||
| Monilitheca | M. minuta | Ulaan Bulag | "Two isolated megasporophylls and megaspore casts."[10] | A sporophyll related to quillworts. | |||
| Nelumbo | N. nogontzavensis | Nogon Tsav | "Leaf and fruit impressions."[5] | Water Lotus. |  | ||
| N. sp. | Atlan Uul | "Leaf impressions."[3] | Water Lotus. | ||||
| Nilssonia | N. sp. | Atlan Uul | "Leaf impressions."[5] | Leaves assigned to Cycadophyta or their own order, Nilssoniales. | .jpg) | ||
| Nyssoidea | N. mongolica | Bugiin Tsav | Middle or Upper | "Fruits." | Likely not in the Nyssaceae family. Also in the Bayanshiree formation.[12][13] | ||
| Phragmites | P. sp. | Atlan Uul, Nogon Tsav | "Leaf and stem impressions."[5] | Reed Grass. |  | ||
| Platanus | P. sp. | Altan Uul | "Leaf impressions."[3] | Sycamore. | .jpg) | ||
| Potamogeton-like | Indeterminate | Ulaan Bulag | "Shoots, leaves, and fruits."[11] | Pondweed. |  | ||
| Silicified Wood | Indeterminate | Altan Uul II, Nemegt | "Petrified wood and trunks."[1] | Indeterminate fossil trees. | |||
| Taxodium | T. sp. | Paleocne border locality, likely Tsagan Khushu | "Leaf impressions."[5] | Cypress. |  | ||
| Trochodendroides | T. sp. | Altan Uul, and Paleocne border locality, likely Tsagan Khushu | "Leaf impressions."[3] | A Katsura relative. |  | ||
| Quereuxia | Q. sp. | Atlan Uul,[3] Nogon Tsav"[5] | "Leaf impressions."[3] | A Water caltrop look-alike. | |||
| Zingiberopsis | Z. sp. | Nogon Tsav | "Leaf impressions."[5] | Ginger relative. |
Invertebrates
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Altanicypris | A. bispinifera | Altan Uul IV, Nemegt | Lower | "Complete carapace and left valve."[14] | An ostracod. | |
| A. multispina | Altan Uul IV, Nemegt | Lower | "Nine carapaces and some detached valves."[14] | An ostracod. | ||
| A. szczechurae | Altan Uul IV, Nemegt | Lower | "Multiple carapaces and detached valves."[14] | An ostracod. | ||
| Candona | C. altanulaensis | Altan Uul IV, Bügiin Tsav, Nemegt | "Multiple specimens with carapaces and valves."[14] | An ostracod. | ||
| cf. C. fabaeformis | Altan Uul IV, Nemegt | Lower | "Several carapaces and detached valves."[14] | An ostracod. | ||
| Candoniella | C. altanica | Altan Uul IV, Bügiin Tsav, Nemegt | "Multiple specimens with carapaces and valves."[14] | An ostracod. | ||
| C. mordvilkoi | Altan Uul IV | Lower | "Three adult carapaces."[15] | An ostracod. | ||
| Cyclocypris | C. transitoria | Bügiin Tsav, Nemegt | "Seven adult carapaces."[14] | An ostracod. | ||
| Cypria | C. elata | Bügiin Tsav, Hermiin Tsav | "Several carapaces and valves."[14] | An ostracod. | ||
| Cypridopsis? | C. bugintsavicus | Altan Uul IV, Bügiin Tsav, Nemegt, Tsagan Khushu | "Ten adult carapaces."[14] | An ostracod. | ||
| Indeterminate | Nemegt | Lower | "Several complete carapaces."[14] | An ostracod. | ||
| Cypris? | C. ectypa | Altan Uul IV, Bügiin Tsav, Nemegt, Ulan Bulag | "Complete carapaces and some detached valves."[14] | An ostracod. | ||
| Cypridea | cf. C. punctilataeformis | Nemegt | "One adult carapace."[15] | An ostracod. | ||
| C. barsboldi | Altan Uul IV, Bügiin Tsav, Nemegt | "Multiple specimens with carapaces and valves."[14] | An ostracod. | |||
| C. cavernosa | Altan Uul IV, Bügiin Tsav, Nemegt, Nogon Tsav | "Multiple specimens with carapaces and valves."[14] | An ostracod. | |||
| C. rostrata | Bügiin Tsav, Nemegt, Nogon Tsav | "Caparaces."[15] | An ostracod. | |||
| Indeterminate | Altan Uul IV, Nemegt | Lower | "Five juvenile carapaces."[14] | An ostracod. | ||
| Gobiella | G. prima | Altan Uul IV, Nemegt | Lower | "Several carapaces and detached valves."[14] | An ostracod. | |
| Khandia | K. stankevitchae | Altan Uul IV, Nemegt | Lower | "Multiple carapaces and valves."[14] | An ostracod. | |
| Leiria | Indeterminate | Nemegt | Lower | "Several detached valves."[14] | An ostracod. | |
| Indeterminate | Nemegt | Lower | "Complete carapace."[14] | An ostracod. | ||
| Limnocythere sp. | Indeterminate | Nemegt | Lower | "Juvenile carapace."[14] | An ostracod. | |
| Lycopterocypris? | cf. L. profunda | Altan Uul IV, Nemegt | Lower | "Multiple complete carapaces and left valve."[14] | An ostracod. | |
| Mongolianella | M. palmosa? | Altan Uul IV, Bügiin Tsav, Nemegt | "Several adult carapaces."[14] | An ostracod. | ||
| Mongolocypris | M. distributa | Altan Uul IV, Bügiin Tsav, Nemegt, Tsagan Khushu | "Multiple specimens with complete carapaces and valves."[14] | An ostracod. | ||
| Nemegtia | N. biformata | Altan Uul IV, Bügiin Tsav, Nemegt, Tsagan Khushu | "Multiple complete carapaces and several detached valves."[14] | An ostracod. | ||
| N. obliquecostae | Altan Uul IV, Nemegt | Lower | "Multiple carapaces and valves."[14] | An ostracod. | ||
| N. reticulata | Altan Uul IV, Bügiin Tsav, Nemegt, Nogon Tsav, Tsagan Khushu | "Several carapaces and detached valves."[14] | An ostracod. | |||
| Paracypridea? | P. mongolica | Altan Uul IV, Nemegt | Lower | "Multiple carapaces and detached valves."[14] | An ostracod. | |
| Rhinocypris sp. | Indeterminate | Nemegt | Lower | "Several carapaces."[14] | An ostracod. | |
| Scabriculocypris | S. ingenicus? | Altan Uul IV, Bügiin Tsav, Naran Bulag, Nemegt, Tsagan Khushu | "Multiple carapaces and valves."[14] | An ostracod. | ||
| S. rasilis? | Altan Uul IV, Nemegt | Lower | "Several carapaces and detached valves."[14] | An ostracod. | ||
| Timiriasevia | cf. T. miaogouensis | Altan Uul IV, Nemegt | Lower | "Seven valves."[14] | An ostracod. | |
| cf. T. opinabilis | Altan Uul IV | Lower | "Adult carapace."[15] | An ostracod. | ||
| T. minuscula | Altan Uul IV, Bügiin Tsav, Nemegt | "Multiple specimens with carapaces and valves."[14] | An ostracod. | |||
| T. naranbulakensis | Altan Uul IV, Bügiin Tsav, Nemegt | "Four carapaces and one right valve."[14] | An ostracod. | |||
| Ziziphocypris | Z. costata | Altan Uul IV, Bügiin Tsav, Nemegt | "Fourteen carapaces."[14] | An ostracod. | ||
Fish
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Harenaichthys | H. lui | Altan Uul, Bügiin Tsav, Hermiin Tsav, Ulan Khushu | "Partial skull parts, isolated and articulated centra, and articulated caudal fin."[16] | An osteoglossomorph. Includes previously reported material.[17][16] | ||
| Osteichthyes indet. | Indeterminate | Bügiin Tsav | "Vertebrae and scales found within a specimen of Deinocheirus''."[18] | A bony fish. |
Amphibians
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Altanulia | A. alifanovi | Altan Uul II | Middle or Upper | "Partial maxilla."[19] | A discoglossid. Its classification has been criticized.[20] | |
Mammals
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Buginbaatar[21] | B. transaltaiensis[21] | Bügiin Tsav | Middle or Upper | "Fragmentary skull."[21] | A multituberculate. | |
| "Gurlin Tsav skull" | Indeterminate | Middle or | Partial skull | A mysterious metatherian, possibly a sparassodont. | ||
| Cimolomyidae indet. | Indeterminate | Gurilin Tsav | Middle to Upper | Humerus | Shares affinities to taxa from the Hell Creek Formation. [22] |
Crocodylomorphs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Paralligator[23] | P. gradilifrons[23] | Nemegt, Nogon Tsav, Ulaan Bulag | Lower | "Partially complete skulls with sparse body elements."[23] | A paralligatorid. |  |
Pterosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Unnamed azhdarchid | Indeterminate | Guriliin Tsav | Middle or Upper | "Fragmentary cervical vertebrae."[24] | A giant azhdarchid. |  |
Turtles
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Gobiapalone | G. breviplastra | Alak Shand Khuduk, Altan Uul I, Bügiin Tsav, Bügiin Tsav II, Nemegt, Ulan Khushu | "Shell and body elements from multiple specimens."[25] | A trionychid. | ||
| Gravemys | G. barsboldi | Bamba Khuduk, Hermiin Tsav, Ingeni Khobur, Tsagan Khushu | "Partial to complete shells."[26][27] | A lindholmemydid. | ||
|
Nanhsiungchelyidae indet. |
Indeterminate | Hermiin Tsav II | Lower | "Shell fragment."[28] | A nanhsiungchelyid. | |
| Indeterminate | Khuren Tsav | "Damaged shell."[28] | A nanhsiungchelyid. | |||
| Indeterminate | Nemegt | Lower | "Partial plastron."[28] | A nanhsiungchelyid. | ||
| Mongolemys | M. elegans | Bügiin Tsav, Hermiin Tsav, Tsagan Khushu | "Skull, shell and body elements from multiple specimens."[29][30] | A lindholmemydid. |  | |
| Mongolochelys | M. efremovi | Altan Uul II, Altan Uul III, Bügiin Tsav, Guriliin Tsav, Hermiin Tsav, Nemegt, Tsagan Khushu | "Skull, shell and body elements from multiple specimens."[31][32] | A sichuanchelyid. | ||
| Nemegtemys | N. conflata | Bügiin Tsav, Nemegt | "Partial plastron elements."[25] | A trionychid. | ||
|
"Trionyx" |
"T". gilbentuensis | Gilbentu | "Fragmentary shell."[25] | A trionychid. | ||
| "T". gobiensis | Altan Uul III, Bamba Khuduk, Nemegt, Tsagan Khushu | "Fragmentary shell and carapace fragments."[25] | A trionychid. | |||
| Trionychidae indet. | Indeterminate | Bamba Khuduk, Bügiin Tsav, Guriliin Tsav, Ingeni Khobur | "Shell and body remains."[25] | A trionychid. Originally identified as Amyda menneri.[25] | ||
Dinosaurs
Ornithischians
Ankylosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| "Dyoplosaurus"[33] | "D". giganteus[33] | Nemegt | Lower | A series of caudal vertebrae, metatarsals, phalanges, osteoderms, and an undescribed partial tail club.[34] | An ankylosaurid now regarded as nomen dubium. |  |
| Saichania[35] | S. chulsanensis[35] | Altan Uul IV | Lower | Partial vertebrae, tail club, and osteoderms.[36] | An ankylosaurid also present in the Baruungoyot Formation. |  |
| Tarchia[35] | T. teresae[36] | Altan Uul IV, Hermiin Tsav I | Lower | A skull, mandibles, vertebrae, tail club, and other undescribed postcranial material.[36] | An ankylosaurid. |  |
| T. tumanovae[37] | Hermiin Tsav | Lower[7] | "Partial skeleton with complete skull."[37] | An ankylosaurid. |  | |
| Tetrapodosaurus-like indet. | Indeterminate | Bügiin Tsav, Shar Tsav | "Footprint casts."[38] | Ankylosaurid tracks. | ||
| Ankylosauridae indet. | Indeterminate | Altan Uul II-III-IV, Bügiin Tsav, Hermiin Tsav I, Khuree Tsav, Nemegt | A partial dentary, caudal vertebrae, dorsal vertebrae, metatarsals, phalanges, pedal phalanx, humeri, partial pelvis, tail clubs, cervical half-rings, osteoderms, skin impressions, and undescribed juveniles and partial skeletons.[34] | Cranial and postcranial material representing numerous individuals of different ages. |  | |
Hadrosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Amblydactylus-like indet. | Indeterminate | Bügiin Tsav, Bügiin Tsav II, Guriliin Tsav, Yagaan Khovil | Middle & Upper[7] | "Footprint casts."[38] | Three-toed hadrosaurs tracks. Attributed to Saurolophus. Some tracks are huge,those from Guriliin Tsav and Bügiin Tsav up to 1m in length. | |
| Barsboldia[39] | B. sicinskii[39] | Nemegt | Lower[7] | "Partial vertebrae, pelvis, and ribs."[39][40] | A hadrosaurid. | .jpg) |
| Hadropodus | Indeterminate | Nemegt | "Numerous footprints."[41] | Hadrosaurid tracks. Attributed to Saurolophus. | ||
| Saurolophus[42] | S. angustirostris[43] | Presence in most localities[44] | "Multiple specimens, including articulated skulls, postcranial skeletons and mass death assemblage."[45][46][47][48] | A saurolophine hadrosaurid which was the most common hadrosaur in the area.[49] |  | |
| Unnamed ichnotaxon | Indeterminate | Nemegt | "Numerous footprint casts with trackways."[50] | Hand and feet hadrosaur tracks. Attributed to Saurolophus. | ||
Pachycephalosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Homalocephale[51] | H. calathocercos[51] | Nemegt | Lower[7] | "Partial skull and skeleton including hindlimbs."[51] | A pachycephalosaurid. |  |
| Prenocephale[51] | P. prenes[51] | Guriliin Tsav, Nemegt | "Complete skull and partial postcranium of several specimens."[51][53] | A pachycephalosaurid. |  | |
| P. sp.[53] | Tsagan Khushu, Nemegt | Lower[7] | "complete left squamosal"; large skull | |||
| Indeterminate | Bugiin Tsav | Middle[52] | "incomplete frontoparietal dome and fragments of associated braincase bones"[53] | |||
Sauropods
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Brontopodus | Indeterminate | Nemegt | Lower | "Large footprint and several four-toed tracks."[54][41] | Sauropod tracks. Tracks were produced by sauropods larger than any in Nemegt known from skeletal remains.[54] Foot measurements vary from 75-90cm in length.[54] Hip height of track maker estimated as 4m.[55] | |
| Brontopodus-like indet. | Indeterminate | Bügiin Tsav, Yagaan Khovil | Middle & Upper [7] | "Footprint casts."[38] | Sauropod tracks. Footprints from Bügiin Tsav are enormous, up to 85 cm in length.[38] | |
| Nemegtosaurus[56] | N. mongoliensis[56] | Nemegt | Lower | "Skulls and body remains from several specimens."[57][58][59] | A titanosaur. |  |
| Opisthocoelicaudia[60] | O. skarzynskii[60] | Altan Uul IV | Lower | "Nearly complete skeleton without the skull and cervical series."[59] | A titanosaur. |  |
| Undescribed sauropods | Indeterminate | Altan Uul I-II-II-IV, Bügiin Tsav, Guriliin Tsav, Hermiin Tsav, Khamaryn Khural, Khuree Tsav, Nemegt, Nogon Tsav, Tsagan Khushu, Ulan Khushu | "Several fragmentary remains.[59] | Sauropod remains that may represent already named taxa,such as Nemegtosaurus.[52] | ||
| Unnamed ichnotaxon | Indeterminate | Nemegt | "Footprint casts with skin impressions."[50] | Four-toed sauropod tracks. Attributed to Opisthocoelicaudia. | ||
Theropods
Alvarezsaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Manipulonyx[61] | M. reshetovi[61] | Hermiin Tsav | Lower | Partial skeleton including several vertebrae, much of the forelimb, and parts of the hindlimb, pectoral girdle, and pelvic girdle[61] | A parvicursorine alvarezsaurid |  |
| Mononykus[62] | M. olecranus[62] | Bügiin Tsav | Middle[52] | "Fragmentary skull, vertebrae, limbs and fragmented pelvis."[63] | An alvarezsaurid |  |
| Indeterminate | Altan Uul III | Lower | "Caudal vertebrae and left hindlimb."[64] | |||
| Nemegtonykus[64] | N. citus[64] | Altan Uul III | Lower | "Partially complete skeleton from two specimens lacking the skull."[64] | An alvarezsaurid | |
Birds
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Brodavis[65] | B. mongoliensis[65] | Bügiin Tsav | "Nearly complete left tarsometatarsus."[65] | A hesperornithine. | ||
| Gurilynia[66] | G. nessovi[66] | Guriliin Tsav | Middle[52] | "Left coracoid and partial humerii."[66] | An enantiornithine. | |
| Judinornis[67] | J. nogontsavensis[67] | Nogon Tsav | "Dorsal vertebra."[67] | A hesperornithine. | ||
| Laevisoolithus[68] | L. sochavai | "Whole egg with partly broken pole"[68] | Laid by a bird or small theropod.[68] | |||
| Subtiliolithus[68] | S. microtuberculatus[68] | "Eggshell fragments"[68] | ||||
| Teviornis[69] | T. gobiensis[69] | Guriliin Tsav | Middle[52] | "Partial forelimbs."[69] | A presbyornithid anseriform. | |
| Unnamed ornithurans | Indeterminate | Tsagan Khushu | "A humerus and two tibiotarsi."[70] | Ornithuran remains. | ||
Dromaeosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Adasaurus[71] | A. mongoliensis[71] | Bügiin Tsav | Middle[52] | "Partial skull and fragmentary postcrania from two specimens."[72] | A dromaeosaurid. |  |
|
Dromaeosauridae indet. |
Indeterminate | Bügiin Tsav | Middle[52] | "Cervical vertebra."[73] | A dromaeosaurid. | |
| Indeterminate | Hermiin Tsav | Lower | "Dorsal vertebra."[74] | |||
| Indeterminate | Khaichin I | "Three teeth."[75] | ||||
| Indeterminate | Nemegt | Lower | "Dorsal vertebra and other elements."[74][76] | |||
| Indeterminate | Indeterminate | Bügiin Tsav | "Footprints with poor claw marks."[77] | Two-toed theropod tracks. Attributed to either Adasaurus or Zanabazar. | ||
| Velociraptor?[78] | V. sp |  |
Ornithomimosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Anserimimus[79] | A. planinychus[79] | Bügiin Tsav | Middle or Upper[7] | "Partial skeleton lacking the skull."[79][80] | An ornithomimid. |  |
| Deinocheirus[81] | D. mirificus[81] | Altan Uul III-IV, Bügiin Tsav | "Complete skull with virtually complete postcranial remains from three specimens."[18] | A giant deinocheirid. |  | |
| Gallimimus[82] | G. bullatus[82] | Presence in most localities[83] | "Multiple specimens with nearly complete skull and postcranial elements."[83][84] | An ornithomimid. |  | |
| Indeterminate | Indeterminate | Bügiin Tsav | "Nine trackways including an articulated Gallimimus foot."[77] | Three-toed theropod tracks. Attributed to ornithomimids. | ||
| Unnamed ornithomimid[85] | Indeterminate | Tsagan Khushu | "Partial vertebral column with fore and hindlimbs."[85][83] | An ornithomimid. | ||
Oviraptorosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Avimimus[86] | A. portentosus[86] | Shar Tsav
Bügiin Tsav[87] |
Middle & Upper [7] | "Skull roof with fragmentary body elements."[88] | An avimimid. |  |
| A. nemegtensis[88] | Nemegt | Lower[7] | "Fragmented skull with partial skeleton."[88] | An avimimid. |  | |
| Conchoraptor? | C. gracilis? | Guriliin Tsav | Middle[52] | "Skull and a flock of articulated individuals."[89] | An oviraptorid. Also present in the Baruungoyot Formation. Possibly representatives of Conchoraptor. |  |
| Elmisaurus[90] | E. rarus[90] | Altan Uul II, Nemegt |
|
"Fragmentary skull and partially skeletons from several specimens."[88][91] | A caenagnathid. |  |
| Elongatoolithidae indet. | Indeterminate | Bügiin Tsav | "Three eggs containing embryonic remains."[92] | Oviraptorid eggs. | ||
| Gobiraptor[93] | G. minutus[93] | Altan Uul III | Lower | "Partial crania with complete lower jaws and fragmented postcrania."[93] | An oviraptorid. | |
| Indeterminate | Indeterminate | Hermiin Tsav, Shar Tsav, Yagaan Khovil | "Footprint casts."[38] | Three-toed theropod tracks. Attributed to Avimimus. | ||
| Nemegtomaia[94] | N. barsboldi[94] | Nemegt | Lower | "Multiple specimens including a nesting specimen and eggs."[95] | An oviraptorid also present in the Baruungoyot Formation. |  |
| Nomingia[96] | N. gobiensis[96] | Bügiin Tsav, Nemegt |
|
"Vertebral series with partial hindlimbs and a referred pygostyle."[88] | A caenagnathid. May be synonymous with Elmisaurus.[91] |  |
| Oksoko[97] | O. avarsan | Bügiin Tsav, Guriliin Tsav | Middle[52] | "Multiple associated skeletons."[97] | An oviraptorid. |  |
| Rinchenia[98] | R. mongoliensis[98] | Altan Uul II | Middle or Upper | "Skull with nearly complete skeleton."[88] | An oviraptorid. |  |
Therizinosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Therizinosaurus[99] | T. cheloniformis[99] | Altan Uul II, Hermiin Tsav, Nemegt | Lower & Middle[7] | "Fore and hindlimb elements from multiple specimens."[100][101] | A giant therizinosaurid. |  |
| Undescribed therizinosaurids | Indeterminate | Altan Uul IV, Bügiin Tsav, Tsagan Khushu [102] | Lower [7]
Middle & Upper [7] |
"Partial remains."[103] | Therizinosaurid remains.[102] Possibly Therizinosaurus. | |
Troodontids
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Borogovia[104] | B. gracilicrus[104] | Altan Uul IV | Lower | "Partial hindlimbs."[104] | A troodontid. | |
| Indeterminate | Indeterminate | Bügiin Tsav | "Footprints with poor claw marks."[77] | Two-toed theropod tracks. Attributed to either Adasaurus or Zanabazar. | ||
| Tochisaurus[105] | T. nemegtensis[105] | Nemegt | Lower | "Left metatarsus."[105] | A troodontid. | |
| Zanabazar[106] | Z. junior[107] | Bügiin Tsav | Middle[52] | "Skull with fragmentary postcranial skeleton."[106] | A troodontid originally identified as "Saurornithoides junior". |  |
Tyrannosaurs
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
|---|---|---|---|---|---|---|
| Alioramus[108] | A. remotus[108] | Nogon Tsav | "Partially preserved skull with very sparse postcranial remains."[108] | An alioramin. |  | |
| A. altai[109] | Tsagan Khushu | "Nearly complete skull with partial postcrania."[109] | An alioramin. |  | ||
| Bagaraatan[110] | B. ostromi[110] | Nemegt | Lower[7] | "Fragmentary lower jaw, hindlimb and caudal vertebrae."[110] | A tyrannosauroid. | |
| Indeterminate | Indeterminate | Bügiin Tsav, Bügiin Tsav II | "Footprint casts."[38] | Three-toed theropod tracks. Attributed to Tarbosaurus. | ||
|
R. kriegsteni[111] |
"Nearly complete skeleton including the skull."[111] | A controversial genus of tyrannosaurid that could be a juvenile Tarbosaurus.[112] |  | |||
| Tarbosaurus[113] | T. bataar[114] | Presence in most localities[2] | "Nearly complete skeletons from multiple specimens."[113][114][2] | A large tyrannosaurid which was the most common large carnivore in the area.[115] |  | |
| Unnamed ichnotaxon | Indeterminate | Nemegt | "Footprint casts with skin impressions."[50] | Three-toed theropod tracks. Attributed to Tarbosaurus. | ||
| Tyrannosauripodidae indet. | Indeterminate | Nemegt | "Five tracks."[41] | Three-toed tyrannosaurid tracks. Attributed to either Alioramus or Tarbosaurus. | ||