Djadochta Formation

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Djadochta Formation
Stratigraphic range: Campanian, 75–71Ma
Type Geological formation
Lithology
Primary Sandstone
Location
Region Asia
Country  Mongolia

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 75-71 mya (million years ago).[1] 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.

The Flaming Cliffs, type locality of the Djadochta Formation

Fauna[edit]

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.[1] It is likely that the nearby Bayn Mandahu represents a slightly younger, perhaps by 1 million years, assemblage of slightly more derived animals, possibly the direct descendants of their Djadochta counterparts.[2]

Amphibians[edit]

A frog of uncertain classification is known from the formation.

Crocodylomorphs[edit]

Crocodylomorphs of the Djadochta Formation
Genus Species Location Stratigraphic position Abundance Notes

Gobiosuchus

G. kielanae

A gobisuchid.

Shamosuchus

S. djadochtaensis

A mesoeucrocodylian.

Zaraasuchus

Z. shepardi

A gobisuchid.

Zosuchus

Z. davidsoni

A basal crocodyliform.

Lizards[edit]

Lizards of the Djadochta Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Aiolosaurus

A. oriens

Anchaurosaurus

A. gilmorei

A primitive iguanid.

Estesia

E. mongoliensis

An anguimorph.

Gobiderma

G. pulchra

An anguimorph.

Mimeosaurus

M. crassus

An agamid.

Pleurodontagama

P. aenigmatodes

An agamid.

Priscagama

P. gobiensis

An agamid.

Xihaina

X. aquilonia

A primitive iguanid.

Mammals[edit]

Mammals of the Djadochta Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Bulganbaatar

B. nemegtbaataroides

A marsupial.

Deltatheridium

D. pretrituberculare

A marsupial.

Deltatheroides

D. cretacicus

A marsupial.

Hyotheridium

H. dobsoni

A therian mammal of uncertain classification.

Kamptobaatar

K. kuczynskii

  • Ukhaa Tolgod

A multituberculate.

Kennalestes

K. gobiensis

A placental. Also present in the Bayan Mandahu Formation.

Kryptobaatar

K. dashzevegi

A multituberculate, the most common mammal in this formation.[1]

Zalambdalestes

Z. lechei

A placental.

Ornithischians[edit]

A hadrosaur of uncertain classification is known from the formation.

Ornithischian dinosaurs of the Djadochta Formation
Genus Species Location Abundance Notes Images

Pinacosaurus

P. grangeri

  • Bayan Dzak[2]
  • Ukhaa Tolgod[2]

An ankylosaur.

P. mephistocephalus

Indeterminate

  • Tugriken Shireh[2]

An ankylosaur.

Protoceratops

P. andrewsi

  • Bayan Dzak[2]
  • Tugriken Shireh[2]
  • Ukhaa Tolgod[3]
  • Zos Wash[3]

A protoceratopsid.

P. hellenikorhinus

Indeterminate

  • Ukhaa Tolgod[2]

A protoceratopsid.

Saurischians[edit]

A sauropod of uncertain classification is known from the 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.
Saurischian dinosaurs reported from the Djadochta Formation
Genus Species Location Material Notes Images

Apsaravis[4]

A. ukhaana[4]

  • Ukhaa Tolgod[5]

"Partial postcranial skeleton."[6]

A basal ornithurine bird only known from this formation.

Byronosaurus hatchlings
Citipati and nest

Archaeornithoides[4]

A. deinosauriscus[4]

"Partial skull."[8]

A coelurosaur of uncertain relationships

Byronosaurus[4]

B. jaffei[4]

  • Ukhaa Tolgod[2]

"Skull and fragmentary postcranium, [and a] fragmentary skull."[9]

A troodontid

Citipati[4]

C. osmolskae[4]

  • Ukhaa Tolgod[2]

"Skeleton with skull, partial postcranium, embryo to adult."[10]

An oviraptorid found brooding its eggs

Citipati sp.

  • Zamyn Khondt[2]

An oviraptorid with a distinctive, tall crest

Gobipteryx

G. minuta

  • Ukhaa Tolgod

An enantiornithine also known from the Barun Goyot Formation

Gobivenator

G. mongoliensis

"Almost complete skeleton." [11]

A troodontid theropod.

Khaan

K. mckennai

  • Ukhaa Tolgod[2]

"[Three] skeletons with skulls."[10]

An oviraptorid.

Kol

K. ghuva

"A well-preserved right foot"[12]

An alvarezsaurid.

Mahakala

M. omnogovae

  • Tugriken Shireh[2]

A dromaeosaurid.

Oviraptor[13]

O. philoceratops[13]

  • Bayan Dzak[2]

"[One] partial skeleton with skull"[14]

An oviraptorid.

?Parvicursor

Indeterminate

  • Tugriken Shireh[2]

An alvarezsaurid.

Quaesitosaurus

Q. orientalis

"Partial skull."[15]

Saurornithoides[13]

S. mongoliensis[13]

  • Bayan Dzak[2]

"Skull with fragmentary postcranial skeleton."[9]

A troodontid.

Shuvuuia[4]

S. deserti[4]

"Skull and postcranial skeleton."[16]

An alvarezsaurid

Tyrannosauridae indet.

Indeterminate[13]

A tyrannosaurid possible referable to Alectrosaurus.

Tsaagan

T. mangas

  • Ukhaa Tolgod[2]

A dromaeosaurid.

Velociraptor[13]

V. mongoliensis[13]

  • Bayan Dzak[2]
  • Tugriken Shireh[2]

A dromaeosaurid.

Unnamed dromaeosaurid

Unnamed

Unnamed troodontid

Unnamed, specimen IGM 100/1005

See also[edit]

Footnotes[edit]

  1. ^ a b c Godefroit, Pascal; Currie, Philip J.; Li, Hong; Shang, Chang Yong; Dong, Zhi-ming (2008). "A new species of Velociraptor (Dinosauria: Dromaeosauridae) from the Upper Cretaceous of northern China". Journal of Vertebrate Paleontology 28 (2): 432–438. doi:10.1671/0272-4634(2008)28[432:ANSOVD]2.0.CO;2. 
  2. ^ a b c d e f g h i j k l m n o p q r s t u Nicholas R. Longrich, Philip J. Currie, Dong Zhi-Ming (2010). "A new oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of Bayan Mandahu, Inner Mongolia". Palaeontology 53 (5): 945–960. doi:10.1111/j.1475-4983.2010.00968.x. 
  3. ^ a b c d e f g h i Norell, M.A.; Clark, J.M.; Turner, A.H.; Makovicky, P.J.; Barsbold, R.; Rowe, T. (2006). "A new dromaeosaurid theropod from Ukhaa Tolgod (Omnogov, Mongolia)". American Museum Novitates 3545: 1–51. doi:10.1206/0003-0082(2006)3545[1:ANDTFU]2.0.CO;2. ISSN 0003-0082. 
  4. ^ a b c d e f g h i j "47.4 Ömnögov', Mongolia; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 596.
  5. ^ Clarke, Julia A., Norell, Mark A. (2002). "The morphology and phylogenetic position of Apsaravis ukhaana from the Late Cretaceous of Mongolia". American Museum Novitates, No. 3387, American Museum of Natural History, New York, NY.
  6. ^ "Table 11.1," in Weishampel, et al. (2004). Page 214.
  7. ^ Spelled "Ömnögov'" in "47.4 Ömnögov', Mongolia; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 596.
  8. ^ "Table 4.1," in Weishampel, et al. (2004). Page 76.
  9. ^ a b "Table 9.1," in Weishampel, et al. (2004). Page 185.
  10. ^ a b "Table 8.1," in Weishampel, et al. (2004). Page 167.
  11. ^ Tsuihiji, T.; Barsbold, R.; Watabe, M.; Tsogtbaatar, K.; Chinzorig, T.; Fujiyama, Y.; Suzuki, S. (2014). "An exquisitely preserved troodontid theropod with new information on the palatal structure from the Upper Cretaceous of Mongolia". Naturwissenschaften. doi:10.1007/s00114-014-1143-9.  edit
  12. ^ a b Turner, A.H.; Nesbitt, S.J.; Norell, M.A. (2009). "A Large Alvarezsaurid from the Cretaceous of Mongolia". American Museum Novitates 3648: 1–14. doi:10.1206/639.1. 
  13. ^ a b c d e f g "48.11 Nei Mongol Zizhiqu, People's Republic of China; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 598.
  14. ^ "Table 8.1," in Weishampel, et al. (2004). Page 166.
  15. ^ "Table 13.1," in Weishampel, et al. (2004). Page 263.
  16. ^ "Table 11.1," in Weishampel, et al. (2004). Page 211.
  17. ^ "Inner Mongolia" is referred to as "Nei Mongol Zizhiqu" in "48.11 Nei Mongol Zizhiqu, People's Republic of China; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 598.

References[edit]

  • Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.

Coordinates: 44°08′19″N 103°43′40″E / 44.13861°N 103.72778°E / 44.13861; 103.72778