# Barun Goyot Formation

The Barun Goyot Formation (also known as Baruungoyot Formation or West Goyot Formation) is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Province of Mongolia.

## Description

It was previously known as the Lower Nemegt Beds occurring beneath the Nemegt Formation and above the Djadokhta Formation. It has been suggested that the Djadokhta and Barun Goyot Formations are lower and upper parts, respectively, of the same lithological unit and the boundary between the two does not exist. The stratotype of the Barun Goyot Formation is the Khulsan locality, east of Nemegt. At Nemegt, only the uppermost barungoyotian beds are visible. The Red Beds of Khermeen Tsav are also considered part of the Barun Goyot Formation. It is approximately 110 metres (360 ft) in thickness, and was laid down roughly 72-71 million years ago. Given the new date for the start of the Maastrichtian (72.1 MYA) a basal Maastrichtian age seems probable. The Barun Goyot Formation preserves an environment of sand dunes, created from wind-eroded rocks (aeolian dunes).

## Paleobiota of the Barun Goyot Formation

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

### Lizards

| Genus | Species | Notes |
| Estesia | Estesia mongoliensis | An anguimorph |
| Gobiderma | Gobiderma pulchrum | A Monstersaur |
| Proplatynotia | Proplatynotia longirostrata | |

### Mammals

| Genus | Species | Notes |
| Asioryctes | A. nemegtensis | An eutherian. |
| Barunlestes | B. butleri | An eutherian. |
| Catopsbaatar | C. catopsaloides | A djadochtatheriid. |
| Chulsanbaatar | C. vulgaris | A multituberculate. |
| Deltatheridium | D. pretrituberculare | A tribosphenid. |
| Nemegtbaatar | N. gobiensis | A multituberculate. |
| Zofialestes | Z. longidens | A eutherian. |

### Dinosaurs
#### Ornithiscians
##### Ankylosaurs

| Genus | Species | Location | Material | Notes |
| Saichania | S. chulsanensis | Hermiin Tsav II, Khulsan | [Three] skulls, mandibles, cervical vertebrae, dorsal vertebrae, ribs, sternum, scapulocoracoids, humerus, ulna, radius, manus, cervical half-rings, and osteoderms. | An ankylosaurid also known from the Nemegt Formation. |
| Tarchia | T. kielanae | Hermiin Tsav II, Khulsan | [Two] partial skulls, osteoderms, and [three] undescribed specimens. | An ankylosaurid also known from a second species, T. teresae, which was found in the Nemegt Formation. |
| Zaraapelta | Z. nomadis | Hermiin Tsav | A partial skull missing the rostrum. | An ankylosaurid known from a subadult individual. |
| Ankylosauridae indet. | Indeterminate | Hermiin Tsav | Dorsal vertebrae, ribs, pectoral girdles, forelimbs, pelvic girdles, hindlimbs, and osteoderms. | An ankylosaurid known from a specimen preserved in a "resting posture". |

##### Ceratopsians

| Genus | Species | Location | Material | Notes |
| Bagaceratops | B. rozhdestvenskyi | Hermin Tsav, Khulsan | "Multiple specimens with partial to nearly complete skulls and skeletons." | A protoceratopsid. Gobiceratops, Lamaceratops, and Platyceratops are now considered synonyms of Bagaceratops. |
| Breviceratops | B. kozlowskii | Khulsan | "Two skulls and partial skeleton remains." | A protoceratopsid. |
| Udanoceratops? | Indeterminate | Baga Tariach | "Partial juvenile specimen." | A giant leptoceratopsid. |

##### Pachycephalosaurs

| Genus | Species | Location | Material | Notes | Images |
| Tylocephale | T. gilmorei | Khulsan | "Partial skull." | A pachycephalosaurid. | |

#### Sauropods

| Genus | Species | Location | Material | Notes | Images |
| Faveoloolithus | F. ningxiaensis | Hermiin Tsav, Ikh Shunkht, Ologoy Ulan Tsav | "Eggs, egg clutches and shells." | Eggs probably laid by a sauropod. | |
| Quaesitosaurus | Q. orientalis | Shar Tsav | "Partial skull." | A titanosaur. | |

#### Theropods
##### Alvarezsaurs

| Genus | Species | Location | Material | Notes |
| Ceratonykus | C. oculatus | Hermiin Tsav | "Partial skull with skeleton." | An alvarezsaurid. |
| Jaculinykus | J. yaruui | Nemegt | A nearly complete articulated skeleton including much of the skull | A parvicursorine alvarezsaurid. |
| Khulsanurus | K. magnificus | Khulsan | "Partial skeleton, including cervical and caudal vertebrae, scapulocoracoids, humerus, and pubis." | An alvarezsaurid. |
| Ondogurvel | O. alifanovi | Nemegt | "Partial postcranial skeleton," including dorsal and sacral vertebrae and hip and leg bones. | An alvarezsaurid. |
| Parvicursor | P. remotus | Khulsan | "Partial vertebrae, pelvic girdle and hindlimbs." | An alvarezsaurid |

##### Birds

| Genus | Species | Location | Material | Notes |
| Gobioolithus | G. major | Gilbent, Khulsan | "Five eggs." | Eggs probably laid by a bird. |
| Gobioolithus | G. minor | Hermiin Tsav, Khulsan | "Eggs with embryonic remains." | Eggs probably laid by Gobipipus. |
| Gobipipus | G. reshetovi | Hermiin Tsav, Khulsan | "Embryonic skulls and skeletons." | An enantiornithine. |
| Gobipteryx | G. minuta | Hermiin Tsav, Khulsan | "Skulls and partial skeletons, and embryonic remains." | An enantiornithine. Also present in the Djadokhta Formation. |
| Hollanda | H. luceria | Hermiin Tsav | "Partial hindlimbs from several specimens." | An ornithuromorph. |
| Protoceratopsidovum' | P. fluxuosum | Hermiin Tsav, Khulsan | "Clutch of 19 eggs and isolated eggs." | Eggs probably laid by a bird. |
| Protoceratopsidovum' | P. minimum | Ikh Shunkht | "Clutch of eggs." | Eggs probably laid by a bird. |
| Protoceratopsidovum' | P. sincerum | Hermiin Tsav | "Partial egg." | Eggs probably laid by a bird. |
| Styloolithus | S. sabathi | Khulsan | "Partial eggs." | Eggs probably laid by a bird. |

##### Dromaeosaurids

| Genus | Species | Location | Material | Notes |
| Hulsanpes | H. perlei | Khulsan | Partial foot and skull bone | A halszkaraptorine |
| Kuru | K. kulla | Khulsan | "Fragmentary skeleton." | A dromaeosaurid. |
| Natovenator | N. polydontus | Hermiin Tsav | Partial articulated skeleton with skull | A halszkaraptorine |
| Shri | S. devi | Khulsan | "Articulated skeleton lacking skull." | A dromaeosaurid. |
| Velociraptorinae indet. | Indeterminate | Hermin Tsav, Khulsan | Not specified. | A dromaeosaurid. |

##### Troodontids

| Genus | Species | Location | Material | Notes | Images |
| Harenadraco | H. prima | Hermiin Tsav | Partial leg, foot, and hip bones | A troodontid | |

##### Oviraptorosaurs

| Genus | Species | Location | Material | Notes |
| Conchoraptor | C. gracilis | Hermin Tsav, Khulsan | "Multiple specimens with skulls and partial skeletons." | An oviraptorid. Also present in the Nemegt Formation. |
| Heyuannia | H. yanshini | Hermiin Tsav | "Partial skulls and skeletons." | An oviraptorid. Originally identified as Ajancingenia and "Ingenia". |
| Nemegtomaia | N. barsboldi | Nemegt | "Nesting specimen." | An oviraptorid. Also present in the Nemegt Formation. |