[F] Djadochta Formation - [Djadoktha Formation] - Mongolia
Mongolia
The Djadochta Formation of Santonian-Campanian (Late Cretaceous) age is famous for yielding the first unquestionable finds of dinosaur eggs (discovered in 1922 by the third Asiatic Expedition led by Roy Chapman Andrews) and numerous exceptionally well-preserved dinosaur skeletons. The type localities of the formation at Bayn Dzak, Ukhaa Tolgod and Tugrig of pre-Altai Gobi (Mongolia) and correlative strata of the Bayan Madahu Formation of the southern Gobi, Inner-Mongolia, China, have been the subject of many later successful paleontological expeditions.
Barsbold, 1983 The fauna from this horizon contains the first carnivorous dinosaurs, found more than half a century ago in the territory of the MPR. At the present time, a wider distribution of faunal groups from the horizon has been established, and two complexes are identified in its composition that are closely related but differ in age, and which characterize two suites deposited after it – the Djadokhtaskaya and the stratigraphically higher-positioned [Barungoyotskaya] Barun Goyot Formation.
The first of these had already been identified as the Djadokhta Formation at the time of the discovery of the Central Asian fauna in the territory of the MPR (Berkey and Morris, 1927), and this name has been used widely in later works (Gradzinsky, Kazmieczak, and Lefeld, 1969; Gradzinsky and Jerzykiewicz, 1972; Lefeld, 1971; Kielan-Jaworowska and Barsbold, 1972). The goal of consistency for naming in the Russian language corresponds more to the acceptance of this subdivision under the name Djadokhtaskaya Svita.
In the Djadokhtaskaya complex itself, the dromaeosaurid Velociraptor mongoliensis, the saurornithoidid Saurornithoides mongoliensis, and the oviraptorid Oviraptor philoceratops are known, first discovered by investigators from the Central Asiatic Expedition. In the [Barungoyotskaya complex] Barun Goyot Formation, the oviraptorid Ingenia yanshini is present, as well as the remains of a dromaeosaurid similar to Velociraptor, but not yet identified more precisely.
The Djadokhtaskaya Velociraptor is a \\\"narrow-skulled\\\" dromaeosaurid, known so far only from this complex. Oviraptorids characterize both of these complexes, and in the Djadokhtaskaya more primitive oviraptorids are present, while the more specialized Ingenia yanshini is found in the [Barungoyotskaya] Barun Goyot Formation.
Saurornithoidids possibly were more widely distributed stratigraphically, as they are also known from the Nemegtskaya horizon. In this manner, both complexes are characterized by a close connection of the types of forms present, and it is not possible to separate them only on theropod information.
However, with consideration of sauropods and the results from studies of mammals, of which both horizon suites are richly endowed (the remains of small mammals are almost unknown in the beds of other Upper Cretaceous horizons), as well as the freshwater fauna (Gradzinsky, Kielan-Jaworowska, and Maryanska, 1977; Maryanska and Osmólska, 1974, 1975), such a subdivision received a more or less weighty and consistent basis. The conclusion regarding the age of the mammals is provided on the basis of comparison with North American forms (Kielan-Jaworowska, 1969, 1970, 1971, 1974a, b, 1975a, b). Faunal deposits from the Djadokhtaskaya Svita form large localities in the south of the country – Bayn Dzak (Shabarak Usu in American publications), Tugreeken Shira, and the recently discovered Dzamin-Khond. The [Barungoyotskaya Svita] Barun Goyot Formation includes the well-known southwestern localities of Khermeen Tsav and Khulsan.
Apsaravis ukhaana ~/~ - Ornithothoraces Ornithurae - Cretaceous Late Campanian
Archaeornithoides deinosauriscus - Tetanurae Coelurosauria - Cretaceous Late
Citipati osmolskae - Oviraptorosauria Oviraptoridae - Cretaceous Late Campanian
Citipati sp. - Oviraptorosauria Oviraptoridae - Cretaceous Late Campanian
Ichabodcraniosaurus - Dromaeosauridae Nomen Nudem - Cretaceous Late
Khaan mckennai - Oviraptorosauria Oviraptoridae - Cretaceous Late Campanian
Mahakala omnogovae - Coelurosauria Dromaeosauridae - Cretaceous Late Campanian
Mononykus olecranus ~/~ - Avialae Alvarezsauridae - Cretaceous Late Campanian
Oviraptor philoceratops - Oviraptorosauria Oviraptoridae - Cretaceous Late Santonian Campanian
Ovoraptor djadochtari - Dromaeosauridae Nomina Dubia - Cretaceous Late ?Santonian Campanian
Pinacosaurus grangeri - Ankylosauria Ankylosauridae - Cretaceous Late Santonian Campanian
Protoceratops andrewsi - Neoceratopia Protoceratopidae - Cretaceous Late ?Santonian Campanian
Saurornithoides mongoliensis - Maniraptora Troodontidae - Cretaceous Late ?Santonian Campanian
Shuvuuia deserti ~/~ - Avialae Alvarezsauridae - Cretaceous Late Campanian
Tsaagan mangas - Coelurosauria Dromaeosauridae - Cretaceous Late
Velociraptor mongoliensis - Coelurosauria Dromaeosauridae - Cretaceous Late ?Santonian Campanian
Dinosaur eggshell - Dinosauria - Cretaceous Late Santonian Campanian
?Tarbosaurus sp. - Theropoda Tyrannosauridae - Cretaceous Late Santonian Campanian
Hadrosaurid indet. - Ornithopoda - Cretaceous Late Santonian Campanian
Sauropoda indet. - Sauropoda - Cretaceous Late Santonian Campanian
The Djadochta Formation of Santonian-Campanian (Late Cretaceous) age is famous for yielding the first unquestionable finds of dinosaur eggs (discovered in 1922 by the third Asiatic Expedition led by Roy Chapman Andrews) and numerous exceptionally well-preserved dinosaur skeletons. The type localities of the formation at Bayn Dzak, Ukhaa Tolgod and Tugrig of pre-Altai Gobi (Mongolia) and correlative strata of the Bayan Madahu Formation of the southern Gobi, Inner-Mongolia, China, have been the subject of many later successful paleontological expeditions.
Barsbold, 1983 The fauna from this horizon contains the first carnivorous dinosaurs, found more than half a century ago in the territory of the MPR. At the present time, a wider distribution of faunal groups from the horizon has been established, and two complexes are identified in its composition that are closely related but differ in age, and which characterize two suites deposited after it – the Djadokhtaskaya and the stratigraphically higher-positioned [Barungoyotskaya] Barun Goyot Formation.
The first of these had already been identified as the Djadokhta Formation at the time of the discovery of the Central Asian fauna in the territory of the MPR (Berkey and Morris, 1927), and this name has been used widely in later works (Gradzinsky, Kazmieczak, and Lefeld, 1969; Gradzinsky and Jerzykiewicz, 1972; Lefeld, 1971; Kielan-Jaworowska and Barsbold, 1972). The goal of consistency for naming in the Russian language corresponds more to the acceptance of this subdivision under the name Djadokhtaskaya Svita.
In the Djadokhtaskaya complex itself, the dromaeosaurid Velociraptor mongoliensis, the saurornithoidid Saurornithoides mongoliensis, and the oviraptorid Oviraptor philoceratops are known, first discovered by investigators from the Central Asiatic Expedition. In the [Barungoyotskaya complex] Barun Goyot Formation, the oviraptorid Ingenia yanshini is present, as well as the remains of a dromaeosaurid similar to Velociraptor, but not yet identified more precisely.
The Djadokhtaskaya Velociraptor is a \\\"narrow-skulled\\\" dromaeosaurid, known so far only from this complex. Oviraptorids characterize both of these complexes, and in the Djadokhtaskaya more primitive oviraptorids are present, while the more specialized Ingenia yanshini is found in the [Barungoyotskaya] Barun Goyot Formation.
Saurornithoidids possibly were more widely distributed stratigraphically, as they are also known from the Nemegtskaya horizon. In this manner, both complexes are characterized by a close connection of the types of forms present, and it is not possible to separate them only on theropod information.
However, with consideration of sauropods and the results from studies of mammals, of which both horizon suites are richly endowed (the remains of small mammals are almost unknown in the beds of other Upper Cretaceous horizons), as well as the freshwater fauna (Gradzinsky, Kielan-Jaworowska, and Maryanska, 1977; Maryanska and Osmólska, 1974, 1975), such a subdivision received a more or less weighty and consistent basis. The conclusion regarding the age of the mammals is provided on the basis of comparison with North American forms (Kielan-Jaworowska, 1969, 1970, 1971, 1974a, b, 1975a, b). Faunal deposits from the Djadokhtaskaya Svita form large localities in the south of the country – Bayn Dzak (Shabarak Usu in American publications), Tugreeken Shira, and the recently discovered Dzamin-Khond. The [Barungoyotskaya Svita] Barun Goyot Formation includes the well-known southwestern localities of Khermeen Tsav and Khulsan.
Apsaravis ukhaana ~/~ - Ornithothoraces Ornithurae - Cretaceous Late Campanian
Archaeornithoides deinosauriscus - Tetanurae Coelurosauria - Cretaceous Late
Citipati osmolskae - Oviraptorosauria Oviraptoridae - Cretaceous Late Campanian
Citipati sp. - Oviraptorosauria Oviraptoridae - Cretaceous Late Campanian
Ichabodcraniosaurus - Dromaeosauridae Nomen Nudem - Cretaceous Late
Khaan mckennai - Oviraptorosauria Oviraptoridae - Cretaceous Late Campanian
Mahakala omnogovae - Coelurosauria Dromaeosauridae - Cretaceous Late Campanian
Mononykus olecranus ~/~ - Avialae Alvarezsauridae - Cretaceous Late Campanian
Oviraptor philoceratops - Oviraptorosauria Oviraptoridae - Cretaceous Late Santonian Campanian
Ovoraptor djadochtari - Dromaeosauridae Nomina Dubia - Cretaceous Late ?Santonian Campanian
Pinacosaurus grangeri - Ankylosauria Ankylosauridae - Cretaceous Late Santonian Campanian
Protoceratops andrewsi - Neoceratopia Protoceratopidae - Cretaceous Late ?Santonian Campanian
Saurornithoides mongoliensis - Maniraptora Troodontidae - Cretaceous Late ?Santonian Campanian
Shuvuuia deserti ~/~ - Avialae Alvarezsauridae - Cretaceous Late Campanian
Tsaagan mangas - Coelurosauria Dromaeosauridae - Cretaceous Late
Velociraptor mongoliensis - Coelurosauria Dromaeosauridae - Cretaceous Late ?Santonian Campanian
Dinosaur eggshell - Dinosauria - Cretaceous Late Santonian Campanian
?Tarbosaurus sp. - Theropoda Tyrannosauridae - Cretaceous Late Santonian Campanian
Hadrosaurid indet. - Ornithopoda - Cretaceous Late Santonian Campanian
Sauropoda indet. - Sauropoda - Cretaceous Late Santonian Campanian
Theropoda indet. - Theropoda - Cretaceous Late Santonian Campanian