Ajancingenia

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Ajancingenia
Skull of Ajancingenia yanshini

Skull of Ajancingenia yanshini

Temporal occurrence
Upper Cretaceous (early Maastrichtian )
72 to 69.9 million years
Locations
Systematics
Theropoda
Coelurosauria
Maniraptora
Oviraptorosauria
Oviraptoridae
Ajancingenia
Scientific name
Ajancingenia
Easter , 2013
Art
Fossil of ajancingenia yanshini

Ajancingenia is a theropod dinosaur from the group of oviraptorosauria from the Upper Cretaceous of Mongolia . This genus is known from some partial skeletons, on the basis of which the only species ( type species ) Ajancingenia yanshini ( Barsbold , 1981) was first described . The specific epithet yanshini honors the academic AL Yanshin. Like other oviraptorosaurs, Ajancingenia displayeda deep, toothless jaw that was shaped into a beak. Presumably it was herbivorous or omnivorous . Within the Oviraptorosauria Ajancingenia is counted to the Oviraptoridae .

Find and naming

A partial skeleton with skull ( holotype ) and five partial skeletons without skull (postcrania) are known from Ajancingenia , which come from the Mongolian Aimag Ömnö-Gobi . The rocks in which the bones were found belong stratigraphically to the Red Beds of Hermiin Tsav of the Nemegt Formation and are therefore around 70 million years old. The holotype material (MPC-D100 / 30) consists inter alia of a number of cranial bones such as the skull and jaw bone, 9 cervical vertebrae, the sacrum , 30 caudal vertebrae (some with Chevron ), 14 dorsal ribs, sternum , humerus , ulna , radius , metacarpals , Pelvic bones ( iliac , pubic , ischium ), femur , shin , fibula , and foot bones.

The genus was described under the name "Ingenia". Since this name was already assigned to a nematode ( Ingenia , Gerlach, 1957) at the time of the description , the name of the later named Oviraptorosaur had to be replaced by a new name according to the International Rules for Zoological Nomenclature (ICZN). Until such a replacement name was proposed, the generic name “Ingenia” was retained and placed in single quotes. In 2013 the new generic name Ajancingenia was given.

features

Ajancingenia is characterized by a massive skeleton and small size. Although the skull is only partially known, Ajancingenia probably showed, like other oviraptorids, an at least flat crest of bone, which is indicated by the shape of the top of the tear bone (lacrimale). The arms were shorter than other oviraptorids: while the sturdy 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 cruciform vertebral arches , while the chevron bones of the anterior ( proximal ) half of the tail were thin and elongated. The ilium was thin and the metatarsals were short and robust.

A study by Osmólska (2004) found numerous vascular prints of the brain on the inside of the skull (on the parietal and frontal bones ) of Ajancingenia . Such imprints are otherwise only found in the ornithomimid Dromiceiomimus as well as in troodontids and dromeosaurids in dinosaurs . The prints confirm that the brain of these dinosaurs touched the bones of the brain skull, i.e. filled the entire brain skull - similar to that of mammals and birds, but different than that of modern reptiles.

swell

Main source

  • Ринченгийн Барсболд : Беззубые хишные динозавры Монголии. In: Совместная советско-монгольская палеонтологическая экспедиция. Труды. Vol. 15, 1981, ZDB -ID 751007-x , pp. 28-39, (In English in the Polyglot Paleontologist: Rinchen Barsbold: Toothless carnivorous dinosaurs of Mongolia. Online (PDF; 735.01 kB) ).

Individual evidence

  1. ↑ a b Halszka Osmólska : Evidence on relation of brain to endocranial cavity in oviraptorid dinosaurs. In: Acta Palaeontologica Polonica. Vol. 49, No. 2, 2004, ISSN  0567-7920 , pp. 321-324, digital version (PDF; 35.4 kB) .
  2. ↑ Halszka Osmólska, Philip J. Currie , Rinchen Barsbold: Oviraptorosauria. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 165-183, here p. 167.
  3. ↑ a b Michael Mortimer: Oviraptorosauria. In: The Theropod Database. Archived from the original on July 8, 2009 ; Retrieved June 5, 2009 .
  4. ↑ Jess Easter: A new name for the oviraptorid dinosaur "Ingenia" yanshini (Barsbold, 1981; preoccupied by Gerlach, 1957). In: Zootaxa . Vol., No., 2013, pp. 184-190, doi : 10.11646 / zootaxa.3737.2.6 .
  5. ↑ Halszka Osmólska, Philip J. Currie, Rinchen Barsbold: Oviraptorosauria. In: David B. Weishampel, Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 165-183, here p. 182.

Web links

Commons : Ajancingenia  - collection of images, videos and audio files