Andaikhudag Formation

The Andaikhudag Formation, in older literature referred to as Unduruh Formation or Ondorukhaa Formation, is an Early Cretaceous (Hauterivian to Barremian) geologic formation in Mongolia.^[1] Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.^[2]

Andaikhudag Formation
Stratigraphic range: Hauterivian-Barremian ~132–125 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Lithology
Primary	Shale
Other	Sandstone
Location
Coordinates	46.0°N 99.6°E / 46.0; 99.6
Approximate paleocoordinates	47.2°N 100.3°E / 47.2; 100.3
Region	Bayankhongor Province
Country	Mongolia
Andaikhudag Formation (Mongolia)

Fossil content

The following fossils have been reported from the lacustrine shales and secondary sandstones of the formation:^[1]

Birds

• Ambiortus dementjevi^[3] - "Vertebrae and forelimb"^[4]
• Holbotia ponomarenkoi^[5]

Insects

• Hymenoptera
  • Kotujisca kholbotensis^[6]
  • Neoxyelula reducta^[7]
  • Palaeoichneumon townesi^[8]
• Diptera
  • Syntemna tele^[9]
  • Ulaia communis^[10]
• Coleoptera
  • Allophalerus bontsaganensis^[11]
  • Tetraphalerus notatus^[11]
• Plecoptera
  • Accretonemoura radiata^[12]

See also

• List of dinosaur-bearing rock formations
  • List of stratigraphic units with few dinosaur genera
• Tsagaantsav Formation