Ajancingenia

Skull of Ajancingenia yanshini

• Mongolia ( Nemegt Formation)

• Ajancingenia yanshini bars Bold 1981

Ajancingenia is a theropod dinosaur from the group of Oviraptorosauria from the Upper Cretaceous of Mongolia. This genus is known from several partial skeletons, based on which the only type ( type species ) Ajancingenia yanshini ( bars Bold, 1981) was first described. The Artepitheth yanshini honors the academics AL Yanshin. Like other Oviraptorosaurier Ajancingenia showed a deep, toothless jaw, which was formed into a beak. Presumably it was a plant or omnivores. Within the Oviraptorosauria Ajancingenia is counted among the Oviraptoridae.

Fund and naming

From Ajancingenia a partial skeleton with skull ( holotype ) and five partial skeletons without skulls ( Postkrania ) are known to originate from the Mongolian Gobi Aimag Ömnö. The rocks in which the bones were found belong stratigraphically to the red beds of Hermiin Tsav the Nemegt formation and are thus about 70 million years old. The holotype material ( MPC-D100/30 ) consists among other things of some skull bones such as the skull and jawbone, 9 cervical vertebrae, the sacrum, 30 caudal vertebrae (some with chevrons ), 14 dorsal ribs, sternum, humerus, ulna, radius, metacarpals, pelvic bone ( ilium, pubis, ischium ), femur, tibia, fibula, and foot bones.

The genus has been described under the name " Ingenia ". As this name was assigned at the time of description but already a nematode ( Ingenia, Gerlach, 1957), had the identical name of the named later Oviraptorosauriers in the International Regulations for Zoological Nomenclature ( ICZN ) are replaced by a new name. Was proposed Until such a substitute name, the generic name " Ingenia " was retained and placed in inverted commas. 2013, the new genus name Ajancingenia was awarded.

Features

Ajancingenia is characterized by a massive skeleton and a small size. Although the skull is only partially known, Ajancingenia was likely as other Oviraptoriden at least one flat bone comb, and then the shape of the top of the lacrimal bone ( lacrimal ) points. The arms were shorter than other Oviraptoriden: While the robust hand showed an enlarged first finger with a thick claw ( ungual ), the third finger was short and thin. The sacrum had seven vertebrae. The caudal vertebrae were characterized by cross-shaped vertebral arches, while the chevron bones of the anterior ( proximal ) half of the tail were thin and elongated. The ilium ( ilium ) was thin, and the metatarsals were short and robust.

A study of Osmólska (2004) found numerous vascular casts of the brain on the inside of the skull ( on the parietal bone and the frontal bone ) of Ajancingenia. Such footprints found in dinosaur otherwise only in the Ornithomimiden Dromiceiomimus and in troodontids and Dromeosauriden. The footprints confirm that the brains of these dinosaurs bones of the skull touched, so the entire cranium filled - similar to mammals and birds, but unlike extant reptiles.

Swell

Main source

• R. bars Bold: Toothless carnivorous dinosaurs of Mongolia. In: Trudy - Sovmestnaya Sovetsko - Mongol'skaya Paleontologicheskaya Ekspeditsiya. No. 15, 1981 ( Original title: Bezzubye khishchnye dinozavry Mongolii ), pp. 28-39 ( English translation in Polyglot Paleontologist: PDF).