Mononykus

Graphical live reconstruction of Mononykus, the fletching shown is based on conjecture

• Asia (Mongolia)

Mononykus is a relatively small, bird-like theropod dinosaur genus from the family of Alvarezsauridae. The only genus of this species is attributed Mononykus olecranus. She lived at the time of the Upper Cretaceous in what is now Mongolia.

Description

The 90 cm long animal was bipedal ( two-legged ) on long hind legs. Like his relatives, he had very short, stubby forelimbs. These ever sat a single claw, which was about five inches long ( Gr. Mononykus = " single claw "). The other claws were regressed. The purpose of this highly specialized arms is controversial, in a study of a similar lifestyle is suspected as the anteaters, the claw has thus served to break insect nests such as termite mounds. The fused wrist bones ( carpal bones ) and the construction of the breastbone ( sternum ) are reminiscent of the anatomy of birds. Mononykus was possibly the feathered dinosaurs.

Finds

The Mononykus attributed finds come from the Djadochta formation and the formation Nemegt Mongolia and the Irish Dabasu Formation of China.

The holotype material (GI N107 / 6; Geological Institute, Mongolian Academy of Sciences) was discovered in 1987 by a dinosaur hunters from the Mongolian Museum of Natural History during the "Soviet - Mongolian expedition Paleontologic ". The site belongs to the geological formation of the Nemegt Nemegt Basin and is located in Bugin Tsav in southwestern Mongolia, a five -square-mile location, which is famous for spectacular finds today. The skeleton consists of front and hind limbs and from vortices when they were discovered the bones were joined together. Within a small radius turtles as well as the remains of Tarbosaurus were discovered bataar.

Relationships

The holotype material was in 1993 by Altangerel Pearl, Luis M. Chiappe, Rinchen bars Bold, James Matthew Clark and Mark Norell, described as a representative of a new basal bird species, briefly mentioned in the journal Nature. An extensive description followed a year later (see references below). You are viewing Mononykus as a sister taxon to all other birds, with the exception of Archaeopteryx. Thus Mononykus would be a side branch of the birds, although it had the Archaeopteryx ancestor, but soon developed back to flightlessness.

The bird status of this species is controversial and has been heavily drawn from various other researchers in doubt. It came between the two opinions to heated debates. Criticisms are particularly unusual forelimbs. Well Hofer ( 1994) commented:

" (...). It would be very difficult to imagine how a primitive bird wing, seeking as did of Archaeopteryx, could have evolved into a forelimb like that of Mononykus " ( in German as: " It would be very difficult to imagine how such a primitive one wing, like that of Archaeopteryx, as could the development of Mononykus to an antecedent. ").

The advocates of the opinion Mononykus was a bird, but defended their opinion ( Chiappe, Norell & Clark, 1997; Padian & Chiappe, 1998).

After 1996, the South African Patagonykus was described, was recognized similarities between this, and the Mononykus urtümlicheren Alvarezsaurus. Alvarezsaurus had already been classified as the sole representative, in the family of Alvarezsauridae within the Ceratosauria. All three species have now been classified as Alvarezsauridae within the Coelurosauria. Shortly thereafter Parvicursor was added to the family, followed Shuvuuia 1998.

The majority of researchers assumed today that it is bird-like Coelurosaurier, but not to birds.