Djadochta Formation

Djadochta Formation
Type	Geological formation
Age	Late Cretaceous (late Santonian?–early Campanian)
Lithology
Primary	Sandstone
Location
Region	Asia

The Djadochta Formation (sometimes transcribed Djadokhta) is situated in central Asia (Gobi Desert) and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya (million years ago). The type locality are the famous "Flaming Cliffs", locally known as Bayanzag ("rich in Haloxylon") or Ulaan-Ereg ("red cliffs").

It preserves an arid habitat of sand dunes, with little freshwater apart from oases and arroyos. In fact, the present-day climate at most Djadochta Formation sites differs little from what it was some 80 Ma, except by being somewhat warmer and perhaps a bit less arid then. This is testimony to the fact that the location has long been so far from any major source of evaporation that little rainfall reached it, even before the Himalayas were uplifted which bar clouds from reaching today's Gobi desert.

Most notable fossil discoveries have been the first confirmed dinosaur eggs (a clutch, probably of Oviraptor) and several dinosaur finds, Protoceratops, Pinacosaurus and Velociraptor being the most prominent.

The Djadochta Formation (sometimes transcribed Djadokhta) is situated in central Asia (Gobi Desert) and dates from the Late Cretaceous Period. Laid down in the early Campanian, possibly starting in the latest Santonian, it is dated somewhat uncertainly at about 84-75 mya (million years ago). The type locality are the famous "Flaming Cliffs", locally known as Bayanzag ("rich in Haloxylon") or Ulaan-Ereg ("red cliffs").

It preserves an arid habitat of sand dunes, with little freshwater apart from oases and arroyos. In fact, the present-day climate at most Djadochta Formation sites differs little from what it was some 80 mya, except by being somewhat warmer and perhaps a bit less arid then. This is testimony to the fact that the location has long been so far from any major source of evaporation that little rainfall reached it, even before the Himalayas were uplifted which bar clouds from reaching today's Gobi desert.

Most notable fossil discoveries have been the first confirmed dinosaur eggs (a clutch, probably of Oviraptor) and several dinosaur finds, Protoceratops, Pinacosaurus and Velociraptor being the most prominent.

Flora and fauna

The fauna of the Djadochta Formation is very similar in composition to the nearby Bayan Mandahu Formation. The two share many of the same genera, but differ in the exact species. For example, the most common mammal in the Djadochta is Kryptobaatar dashzevegi, while in the Bayan Mandahu, it is the closely related Kryptobaatar mandahuensis. Similarly, the dinosaur fauna of the Djadochta includes Protoceratops andrewsi and Velociraptor mongoliensis, which the Bayan Mandahu yields Protoceratops hellenikorhinus and Velociraptor osmolskae.

Amphibians

Amphibians of the Djadochta Formation
Taxa	Presence	Description	Images
Anuran sp.		A frog of uncertain classification.

Birds and other theropods

Theropod dinosaurs of the Djadochta Formation
Taxa	Presence	Description	Images
Apsaravis ukhaana		A basal ornithurine bird.	Khaan Saurornithoides Velociraptor
Archaeornithoides deinosauriscus		A coelurosaur of uncertain relationships.
Citipati osmolskae		An oviraptorid found brooding its eggs.
Citipati sp.		An oviraptorid with a distinctive, tall crest.
Khaan mckennai		An oviraptorid.
Kol ghuva		An alvarezsaurid.
Mahakala omnogovae		A dromaeosaurid.
Oviraptor philoceratops	May also be present in the Bayan Mandahu Formation.	An oviraptorid.
Saurornithoides mongoliensis	Also present in the Bayan Mandahu Formation.	A troodontid.
Shuvuuia deserti		An alvarezsaurid.
Tarbosaurus? sp.		A tyrannosaur.
Tsaagan mangas		A dromaeosaurid.
Velociraptor mongoliensis	Also present in the Bayan Mandahu Formation.	A dromaeosaurid.

Crocodylomorphs

Crocodylomorphs of the Djadochta Formation
Taxa	Presence	Description	Images
Gobiosuchus kielanae		A gobisuchid.
Shamosuchus djadochtaensis		A mesoeucrocodylian.
Zaraasuchus shepardi		A gobisuchid.
Zosuchus davidsoni		A basal crocodyliform.

Lizards

Lizards of the Djadochta Formation
Taxa	Presence	Description	Images
Anchaurosaurus gilmorei		A primitive iguanid.
Estesia mongoliensis		An anguimorph.
Gobiderma pulchra		An anguimorph.
Mimeosaurus crassus		An agamid.
Pleurodontagama aenigmatodes		An agamid.
Priscagama gobiensis		An agamid.
Xihaina aquilonia		A primitive iguanid.
Aiolosaurus oriens

Mammals

Mammals of the Djadochta Formation
Taxa	Presence	Description	Images
Bulganbaatar nemegtbaataroides		A marsupial.
Deltatheridium pretrituberculare		A marsupial.
Deltatheroides cretacicus		A marsupial.
Hyotheridium dobsoni		A therian mammal of uncertain classification.
Kamptobaatar kuczynskii		A multituberculate.
Kennalestes gobiensis	Also present in the Bayan Mandahu Formation.	A placental.
Kryptobaatar dashzevegi		A multituberculate, the most common mammal in this formation.
Zalambdalestes lechei		A placental.

Ornithischians

Ornithischian dinosaurs of the Djadochta Formation
Taxa	Presence	Description	Images
Hadrosaurid sp.		A hadrosaur of uncertain classification.	Protoceratops
Pinacosaurus grangeri		An ankylosaur.
Protoceratops andrewsi		A ceratopsian.

Sauropods

Sauropod dinosaurs of the Djadochta Formation
Taxa	Presence	Description	Images
Sauropod sp.		A sauropod of uncertain classification.

See also

• Barun Goyot Formation
• List of fossil sites (with link directory)
• Nemegt Formation
• List of dinosaur-bearing rock formations

Footnotes