Adasaurus

Taxobox|
name = "Adasaurus"
fossil_range = Late Cretaceous
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Saurischia
subordo = Theropoda
infraordo = Coelurosauria
familia = Dromaeosauridae
subfamilia = Dromaeosaurinae
genus = "Adasaurus"
genus_authority = Barsbold, 1983
subdivision_ranks = Species
subdivision =
*"A. mongoliensis" Barsbold, 1983

"Adasaurus" (pronEng|ˌɑːdəˈsɔrəs (AH-dah-SAWR-us); "Ada's lizard") is a genus of dromaeosaurid theropod dinosaur from the Late Cretaceous Period of what is now Central Asia. It was a small bipedal carnivore with a sickle-shaped claw on the second toe of each hind foot. An adult was probably about 8 feet (2.5 meters) from the snout to the end of the tail.

Ada is an evil spirit in the national mythology of Mongolia. The name also includes the Greek word "sauros" meaning 'lizard', the most common suffix used in dinosaur names. There is one species ("A. mongoliensis"), named after the country of Mongolia, where the fossil was found. Both genus and species were named and described in 1983 by famous Mongolian paleontologist Rinchen Barsbold.

"Adasaurus" is a member of Dromaeosauridae, a theropod family thought to be very closely related to birds. Relationships within the family are poorly understood, but "Adasaurus" seems to be a member of the subfamily Dromaeosaurinae, along with the Mongolian "Achillobator" and several North American species (Norell & Makovicky 2004; Makovicky et al. 2005). Other dromaeosaurids include "Deinonychus", "Velociraptor", "Microraptor", and "Buitreraptor". "Adasaurus" is unique among dromaeosaurids in having much smaller sickle claws on its hind feet.

Two specimens of "Adasaurus" have been found, both from the Nemegt Formation of Bayankhongor Province in Mongolia. The holotype is an incomplete skull associated with some bones of the skeleton, including all three bones of the pelvis. The second specimen, also described in the original paper, consists of the back end of another skeleton, including the hindlimbs. Both specimens are currently in the collection of the Mongolian Geological Institute in Ulaanbaatar, Mongolia.

The age of the Nemegt, like most of Mongolia's Late Cretaceous sediments, is not known for certain, but it is commonly thought to belong to the Maastrichtian stage of the Late Cretaceous Period (Jerzykiewicz & Russell 1991). Therefore the Nemegt was deposited somewhere between 74 and 65 million years ago. Other dinosaurs found in this formation include "Tarbosaurus", "Anserimimus", and "Saurolophus".

References

*Barsbold, R. 1983. Carnivorous dinosaurs from the Cretaceous of Mongolia. "Transactions of the Joint Soviet-Mongolian Paleontological Expedition". 19. 5-119. [in Russian]
*Jerzykiewicz, T. & Russell, D.A. 1991. Late Mesozoic stratigraphy and vertebrates of the Gobi Basin. "Cretaceous Research" 12(4): 345-446.
*Makovicky, J.A., Apesteguía, S., & Agnolín, F.L. 2005. The earliest dromaeosaurid theropod from South America. Nature 437: 1007-1011.
*Norell, M.A. & Makovicky, J.A. 2004. Dromaeosauridae. In: Weishampel, D.B., Dodson, P. & Osmolska, H. (Eds.). "The Dinosauria" (2nd Edition). Berkeley: University of California Press. Pp. 196-209.