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). 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.

 File:Resized pan-flaming-cropped2.jpg

## 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*. 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.

### Amphibians

A frog of uncertain classification is known from the formation.

### Eggs

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## See also

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

## Footnotes

1. ↑ 1.0 1.1 1.2 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. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 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. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 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. ISSN 0003-0082. doi:10.1206/0003-0082(2006)3545[1:ANDTFU]2.0.CO;2.
4. ↑ 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.
5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 "47.4 Ömnögov', Mongolia; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 596.
6. ↑ 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.
7. ↑ "Table 11.1," in Weishampel, et al. (2004). Page 214.
8. ↑ Spelled "Ömnögov'" in "47.4 Ömnögov', Mongolia; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 596.
9. ↑ "Table 4.1," in Weishampel, et al. (2004). Page 76.
10. ↑ 10.0 10.1 "Table 9.1," in Weishampel, et al. (2004). Page 185.
11. ↑ 11.0 11.1 "Table 8.1," in Weishampel, et al. (2004). Page 167.
12. ↑ 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.
13. ↑ 13.0 13.1 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.
14. ↑ 14.0 14.1 14.2 14.3 14.4 14.5 14.6 "48.11 Nei Mongol Zizhiqu, People's Republic of China; 2. Djadochta Formation." Weishampel, et al. (2004). Pg. 598.
15. ↑ "Table 8.1," in Weishampel, et al. (2004). Page 166.
16. ↑ "Table 13.1," in Weishampel, et al. (2004). Page 263.
17. ↑ "Table 11.1," in Weishampel, et al. (2004). Page 211.
18. ↑ 18.0 18.1 18.2 18.3 18.4 18.5 Mortimer, M (2004). "Tyrannosauroidea". *The Theropod Database*. Retrieved 2007-08-21.
19. ↑ "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.
20. ↑ 20.0 20.1 Ksepka, Daniel T.; Norell, Mark A. (2004). "Ornithomimosauria cranial material from Ukhaa Tolgod (Omnogov, Mongolia)". *American Museum Novitates* **3448**: 1–4. ISSN 0003-0082. doi:10.1206/0003-0082(2004)448<0001:ocmfut>2.0.co;2.
21. ↑ 21.0 21.1 Varricchio, D.J. and D.E. Barta (2015). "Revisiting Sabath's "Larger Avian Eggs" from the Gobi Cretaceous" *Acta Palaeontologica Polonica* 60(1):11-25.
22. ↑ 22.0 22.1 22.2 22.3 22.4 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.

## References

* 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

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