Djadochta Formation

The Djadochta Formation (sometimes transcribed Djadokhta) is a geological formation situated in central Asia (Gobi Desert), dating 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").

Djadochta Formation
Stratigraphic range: Campanian, 75–71 Ma
↓
Flaming Cliffs (Bayan Dzak), the type locality of the Djadochta Formation
TypeGeological formation
Unit ofShamo Group
Sub-unitsBayn Dzak & Tugrugyin members
UnderliesBarun Goyot Formation
OverliesAlagteeg Formation
ThicknessOver 90 m (300 ft) (composite)
Lithology
PrimarySandstone
OtherMudstone
Location
Coordinates44°08′19″N 103°43′40″E
Approximate paleocoordinates30.7°N 9.2°E / 30.7; 9.2
RegionÖmnögov
Country Mongolia
Djadochta Formation (Mongolia)

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.

Fossil content

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 Bayan 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

A frog of uncertain classification is known from the formation.

Crocodylomorphs
GenusSpeciesLocationStratigraphic positionAbundanceNotes
Gobiosuchus G. kielanae A gobisuchid
Shamosuchus S. djadochtaensis A mesoeucrocodylian
Zaraasuchus Z. shepardi A gobisuchid
Zosuchus Z. davidsoni A basal crocodyliform

Lizards
GenusSpeciesLocationStratigraphic positionAbundanceNotesImages
Aiolosaurus A. oriens
Anchaurosaurus A. gilmorei A primitive iguanid
Estesia E. mongoliensis A varanid
Gobiderma G. pulchra An anguimorph
Mimeosaurus M. crassus An agamid
Pleurodontagama P. aenigmatodes An agamid
Priscagama P. gobiensis An agamid
Saichangurvel S. davidsoni A gobiguanian iguanid
Telmasaurus T. grangeri A varanid
Xihaina X. aquilonia A primitive iguanid

Mammals
GenusSpeciesLocationStratigraphic positionAbundanceNotesImages
Bulganbaatar B. nemegtbaataroides A multituberculate
Deltatheridium D. pretrituberculare A metatherian
Deltatheroides D. cretacicus A metatherian
Hyotheridium H. dobsoni A therian mammal of uncertain classification
Kamptobaatar K. kuczynskii Ukhaa Tolgod A multituberculate
Kennalestes K. gobiensis A eutherian. Also present in the Bayan Mandahu Formation.
Kryptobaatar K. dashzevegi A multituberculate, the most common mammal in this formation.[1]
Zalambdalestes Z. lechei A eutherian

Ornithischians
GenusSpeciesLocationMaterialNotesImages
Minotaurasaurus M. ramachandrani Ukhaa Tolgod[4][5] An ankylosaurid
Pinacosaurus P. grangeri Alag Teg, Bayan Dzak, Tugriken Shire, Ukhaa Tolgod An ankylosaurid
Indeterminate Tugriken Shire[2] An ankylosaurid
Plesiohadros[6] P. djadokhtaensis Alag Teg A hadrosauroid
Protoceratops P. andrewsi Bayan Dzak, Tugriken Shire, Ukhaa Tolgod, Zos Wash A protoceratopsid
Indeterminate Ukhaa Tolgod[2] A protoceratopsid
Udanoceratops U. tschizhovi Udan-Sahr

Theropods
Saurischian dinosaurs
GenusSpeciesLocationMaterialNotesImages
Alvarezsauridae indet. Indeterminate Tugriken Shire "Partial braincase with skeleton."[7] An alvarezsaurid originally identified as Mononykus, and often referred as Parvicursor.
Aepyornithomimus[8] A. tugrikinensis Tugriken Shire An ornithomimid
Almas[9] A. ukhaa Ukhaa Tolgod A troodontid
Apsaravis[10] A. ukhaana[10] Ukhaa Tolgod[11] "Partial postcranial skeleton."[12] A basal ornithurine bird
Archaeornithoides[10] A. deinosauriscus[10] Bayn Dzak[13] "Partial skull."[14] A coelurosaur of uncertain relationships
Byronosaurus[10] B. jaffei[10] Ukhaa Tolgod[2] "Skull and fragmentary postcranium, [and a] fragmentary skull."[15] A troodontid
Citipati[10] C. osmolskae[10] Ukhaa Tolgod[2] "Skeleton with skull, partial postcranium, embryo to adult."[16] An oviraptorid
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." [17] A troodontid theropod
Halszkaraptor[18] H. escuilliei Ukhaa Tolgod[2] A halszkaraptorine
Khaan K. mckennai Ukhaa Tolgod[2] "[Three] skeletons with skulls."[16] An oviraptorid
Kol K. ghuva Ukhaa Tolgod[19] "A well-preserved right foot"[19] A large alvarezsaurid
Mahakala M. omnogovae Tugriken Shire[2] A halszkaraptorine
Ornithomimosauria indet. Indeterminate Ukhaa Tolgod Partial braincase, jaw tips, ribs, and vertebral fragments.[20][21] An ornithomimid.
Oviraptor[22] O. philoceratops[22] Bayn Dzak[2] "One partial skeleton with skull, associated nest and juvenile"[23][24] An oviraptorid
Saurornithoides[22] S. mongoliensis[22] Bayn Dzak[2] "Skull with fragmentary postcranial skeleton."[15] A troodontid
Shuvuuia[10] S. deserti[10] Ukhaa Tolgod,[2] Zos Wash[3] "Skull and postcranial skeleton."[25] An alvarezsaurid
cf. Tarbosaurus[26] Indeterminate[26] A tyrannosaurid, may actually be Zhuchengtyrannus.[26] More ancient than Tarbosaurus.
Tyrannosauridae indet. Indeterminate[22] Bayn Dzak,[2] Bayan Mandahu[2][27] A tyrannosaurid possibly referable to Alectrosaurus
Tsaagan T. mangas Ukhaa Tolgod[2] A dromaeosaurid
Velociraptor[22] V. mongoliensis[22] Bayn Dzak, Tugriken Shire, Ukhaa Tolgod[2] A dromaeosaurid
Unnamed dromaeosaurid Unnamed Zos Wash[3]
Unnamed troodontid Unnamed, specimen IGM 100/1005 Ukhaa Tolgod[3]
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.

Eggs
OogenusOospeciesLocationMaterialNotes
Styloolithus[28] S. sabathi Bayn Dzak[28] Probably avian
Protoceratopsidovum[29]
  • P. sincerum
  • P. minimum
  • P. fluxuosum
Elongatoolithus[29]
  • E. frustrabilis
  • E. Subtitectorius
Spheroolithus[29]
  • S. maiasauroides
  • S. tenuicorticus
Macroolithus[29] M. mutabilis
Subtiliolithus[29] spp.

Panorama
Panoramic view of the Flaming Cliffs, type locality of the Djadochta Formation

See also

References
  1. 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. 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. 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. hdl:2246/5823. ISSN 0003-0082.
  4. Alicea, J.; Loewen, M. (2013). "New Minotaurasaurus material from the Djodokta Formation establishes new taxonomic and stratigraphic criteria for the taxon". Journal of Vertebrate Paleontology. Program and Abstracts: 76.
  5. Penkalski, P.; Tumanova, T. (2017). "The cranial morphology and taxonomic status of Tarchia (Dinosauria: Ankylosauridae) from the Upper Cretaceous of Mongolia". Cretaceous Research. 70: 117–12. doi:10.1016/j.cretres.2016.10.004.
  6. Khishigjav Tsogtbaatar, David Weishampel, David C. Evans, and Mahito Watabe (2014). A new hadrosauroid (Plesiohadros djadokhtaensis) from the Late Cretaceous Djadokhtan fauna of southern Mongolia. [pgs. 108-135] In: David A. Eberth and David C. Evans (eds). Hadrosaurs. Proceedings of the International Hadrosaur Symposium. Indiana University Press. ISBN 978-0-253-01385-9.
  7. Longrich & Currie (2009). Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: Implications for the systematics and ecology of the Alvarezsauridae. Cretaceous Research. 30(1), 239-252.
  8. Chinzorig, T.; Kobayashi, Y.; Tsogtbaatar, K.; Currie, P. J.; Watabe, M.; Barsbold, R. (2017). "First Ornithomimid (Theropoda, Ornithomimosauria) from the Upper Cretaceous Djadokhta Formation of Tögrögiin Shiree, Mongolia". Scientific Reports. 7 (5835): 5835. Bibcode:2017NatSR...7.5835C. doi:10.1038/s41598-017-05272-6. PMC 5517598. PMID 28724887.
  9. Pei, R.; Norell, M.A.; Barta, D.E; Bever, G.S.; Pittman, M.; Xu, Xing (2017). "Osteology of a New Late Cretaceous Troodontid Specimen from Ukhaa Tolgod, Ömnögovi Aimag, Mongolia". American Museum Novitates. 3889 (3889): 1–47. doi:10.1206/3889.1. S2CID 90883541.
  10. "47.4 Ömnögov', Mongolia; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 596.
  11. 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.
  12. "Table 11.1," in Weishampel, et al. (2004). Page 214.
  13. Spelled "Ömnögov'" in "47.4 Ömnögov', Mongolia; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 596.
  14. "Table 4.1," in Weishampel, et al. (2004). Page 76.
  15. "Table 9.1," in Weishampel, et al. (2004). Page 185.
  16. "Table 8.1," in Weishampel, et al. (2004). Page 167.
  17. 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. 101 (2): 131–142. Bibcode:2014NW....101..131T. doi:10.1007/s00114-014-1143-9. PMID 24441791. S2CID 13920021.
  18. Cau, A.; Beyrand, V.; Voeten, D.; Fernandez, V.; Tafforeau, P.; Stein, K.; Barsbold, R.; Tsogtbaatar, K.; Currie, P.; Godefroit, P. (2017). "Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs". Nature.
  19. 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. hdl:2246/5967. S2CID 59459861.
  20. Makovicky, P. J.; Norell, Mark A. (1998). "A partial ornithomimid briancase from Ukhaa Tolgod (Upper Cretaceous, Mongolia)". American Museum Novitates. 3247: 1–16.
  21. Ksepka, Daniel T.; Norell, Mark A. (2004). "Ornithomimosauria cranial material from Ukhaa Tolgod (Omnogov, Mongolia)". American Museum Novitates. 3448: 1–4. doi:10.1206/0003-0082(2004)448<0001:ocmfut>2.0.co;2. hdl:2246/2813. ISSN 0003-0082.
  22. "48.11 Nei Mongol Zizhiqu, People's Republic of China; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 598.
  23. "Table 8.1," in Weishampel, et al. (2004). Page 166.
  24. Norell, Balanoff, Barta and Erickson (2018). A second specimen of Citipati osmolskae associated with a nest of eggs from Ukhaa Tolgod, Omnogov Aimag, Mongolia. American Museum Novitates. 3899, 44 pp.
  25. "Table 11.1," in Weishampel, et al. (2004). Page 211.
  26. Mortimer, M (2004). "Tyrannosauroidea". The Theropod Database. Archived from the original on 2013-09-29. Retrieved 2007-08-21.
  27. "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.
  28. Varricchio, D.J.; Barta, D.E. (2015). "Revisiting Sabath's "Larger Avian Eggs" from the Gobi Cretaceous". Acta Palaeontologica Polonica. 60 (1): 11–25.
  29. Mikhailov, K. E. (1995) "Systematic, faunistic and stratigraphic diversity of Cretaceous eggs in Mongolia: comparison with China." Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Beijing. Short Papers... Beijing. pp. 165-168.

Bibliography
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