Nemegtomaia

Head reconstruction of Nemegtomaia barsboldi

• Mongolia ( Nemegt Formation)

• Nemegtomaia barsboldi ( Lü et al., 2004)

Nemegtomaia is a theropod dinosaur from the group of Oviraptorosauria, who lived in the Upper Cretaceous of Mongolia.

The only known type ( type species ) of the genus, Nemegtomaia barsboldi, was first described in 2004. Nemegtomaia was derived ( advanced ) Oviraptorosaurier who showed a short, deep skull with toothless, formed into a beak pines as related genera. Presumably it was a plant or omnivores. Within the Oviraptorosauria Nemegtomaia is counted among the Oviraptoridae. Phylogenetic studies show that Nemegtomaia was more closely related to Citipati than with other known Oviraptoriden.

Fund and naming

So far, an incomplete skeleton with a nearly complete skull known ( holotype, catalog number 1001 GIN 2112; originally PC 1001 2112 ).

The fossils were discovered by the team of the Highland International Dinosaur Project in the Nemegt locality in south-western Mongolia in the summer of 1996. Stratigraphy of this locality belongs to Nemegt lineup and was in the middle Maastrichtian, about 68 million years ago, deposited. Lü et al. described the discovery in 2002, initially as Ingenia sp. - For at least five autapomorphies ( unique features ) on the skull, the researchers in 2004, but its own genus and species for the Fund, which they called Nemegtia barsboldi. Later it turned out that the genus name Nemegtia already a fossil shell cancer ( Ostracoda ) was awarded from the same rock formation, so the genus was renamed Nemegtomaia 2005. The skeleton is now in the Paleontological Center of the Mongolian Academy of Sciences in the Mongolian capital of Ulaanbaatar.

In addition to the almost complete skull almost all cervical vertebrae in anatomical composite include get, some vertebrae, the almost complete sacrum ( sacrum ), pelvic bones ( both ilia ( Ilia ), the proximal ends of pubic and ischial ( pubis and ischium ) ) parts of the humerus (upper arm bones), the spoke (radius ) and the proximal end of the femur (thigh bone ).

The original generic name Nemegtia indicates the Nemegt basin, the rock unit from which originate the fossils. The Artepitheth barsboldi honors the paleontologist Rinchen bars Bold, one of the leaders of the Highland International Dinosaur Project. The new valid genus name Nemegtomaia means as much as "Mother of Nemegt ".

Features

Like some other Oviraptoriden Nemegtomaia showed a skull crest, from the nose and premaxillary bone ( premaxilla ) was formed. The front edge of this ridge was more or less vertical, while the highest point ran in a circular arc. As with other Oviraptoriden the Zwischenkieferbein, the upper jaw bone ( maxilla ) and the vomer ( vomer ) formed a hard palate. The lying before the eyes antorbitale cavity consisted of two skulls windows: a large antorbitalen window in the rear area of the cavity and a small Maxillarfenster the front. Between prefrontal and lacrimal bone can be found on the left side of the skull, a triangular bone, which is likely to be a prefrontal. This bone is known by any other Oviraptorosaurier.

In the rest of the skeleton ( Postkranium ) that follows the skull, 8 sacral vertebrae ( sacral vertebrae ) could be identified - a similar number to other Oviraptoriden as Heyuannia, but significantly more than in most other non-avian theropods -. Almost all cervical vertebrae are preserved in natural, anatomical composite; total Nemegtomaia showed 13 cervical vertebrae.