- Adasaurus mongoliensis
Adasaurus is a genus of carnivorous dinosaur from the group of Dromaeosauridae. So far, two incomplete skeletons are known to originate from the Upper Cretaceous of Mongolia. The only type ( type species ) is Adasaurus mongoliensis. The characteristic sickle Dromaeosauriden claw at the second (inner) of the foot toe was smaller than in Adasaurus related genera and not greater than the remaining claws of the foot.
Adasaurus is estimated to have a length of about 2.4 meters and a weight of about 36 kg. Unlike other Dromaeosauriden the penultimate phalanx lacked ( Phalange ) of the second, the sickle claw -bearing toe asymmetric ridges. Therefore, it is believed that the crescent claw at Adasaurus may be another function than others had Dromaeosauriden. The hind legs appear in comparison with other Dromaeosauriden very robust.
This species shows some similarities with Velociraptor mongoliensis, another Mongolian Dromaeosauriden: To show both classes a fused Scapulocoracoid ( scapula and coracoid ) and merged with the metatarsal distal (lower ) foot bones. However, differences can be seen in some cranial bones and the Pleurocoelen ( air-filled chambers ) of the sacral vertebrae, which were present only in the anterior sacral vertebrae in Adasaurus. From other Dromaeosauriden to Adasaurus be in addition to the reduced sickle claw by features in the skull and pelvis delimit: So the frontal bone ( frontal ) shows a flat dorsal ridge; also the opening ( foramen ) of the Surangulare was ( a bone of the lower jaw ) is relatively large. The Präacetabular process of the ilium ( ilium ) shows a notched front edge.
The systematic position within the Dromaeosauridae is controversial. Rinchen bars Bold arranged Adasaurus to in his first description of Dromaeosaurinae; This assignment was followed by a series of later authors. However, a recent study by Currie and Rich Long (2009 ) provides Adasaurus representing the Velociraptorinae.
Findings, research history and naming
So far, two fragmentary skeletons are known to originate from the Nemegt Formation, a rock unit in the southwestern Mongolia. The holotype specimen ( specimen number MPD 100/20 ) comes from the Bugin - Tsav locality and consists of the back of the skull and the Postkranium (residual skeleton); missing ribs, arms and some foot bones. A second skeleton ( copy number MPD 100/21 ) consists of the right foot and two tail vertebrae. The fossils date from the early Maastrichtian and are approximately 72-69 million years old.
The name Adasaurus first appeared in 1977 in a short publication of the famous Mongolian paleontologist Rinchen bars Bold; here the fossils but were merely illustrates. In 1983, Rinchen bars Bold published a very brief description based on the two skeletons. In 2006, Kubota and bars Bold presented a re-examination of the fossils.
Rinchen bars Bold named the genus after Ada, an evil spirit from the Mongolian mythology. The Style epithet mongoliensis has the locality, the country Mongolia.