Djadochta Formation


The Djadochta Formation is a geological formation situated in central Asia, 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. The type locality are the famous "Flaming Cliffs", locally known as Bayanzag or Ulaan-Ereg.
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 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. 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.

Amphibians

A frog of uncertain classification is known from the formation.

Crocodylomorphs

Lizards

Mammals

Ornithischians

Saurischians

Eggs

OogenusOospeciesLocationMaterialNotes
StyloolithusS. sabathiBayn DzakProbably avian
Protoceratopsidovum
  • P. sincerum
  • P. minimum
  • P. fluxuosum
Elongatoolithus
  • E. frustrabilis
  • E. Subtitectorius
    • Spheroolithus
  • S. maiasauroides
  • S. tenuicorticus
    • MacroolithusM. mutabilis
    Subtiliolithusspp.

    Panorama