Adasaurus

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Adasaurus
Temporal range: Late Cretaceous, 70–68 Ma
Adasaurus hip.png
Restored pelvis from the holotype IGM 100/20
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Dromaeosauridae
Genus: Adasaurus
Barsbold, 1983
Type species
Adasaurus mongoliensis
Barsbold, 1983

Adasaurus (/ˌɑːdəˈsɔːrəs/ AH-də-SAWR-əs; "Ada's lizard") is a genus of dromaeosaurid theropod dinosaur that lived in Asia during the Late Cretaceous period. It was a small, ground-dwelling bipedal carnivore with a sickle-shaped claw on the second toe of each hind foot, although very reduced.[1]

Discovery and naming

Adasaurus was named and described in 1983 by Mongolian paleontologist Rinchen Barsbold. Two specimens of Adasaurus have been found, both from the Nemegt Formation in the Gobi Desert of southern Mongolia. The genus name Adasaurus is taken from Ada, an evil spirit in the mythology of Mongolia, and the Greek word sauros meaning 'lizard'. The species name, for the single species, (A. mongoliensis), refers to the country of origin: Mongolia.[1]

Description

Illustration

The holotype, IGM 100/20, is an incomplete skeleton with partial skull, including the vertebral column except the back of the tail, all three bones of the pelvis, the shoulder girdle and the hindlimbs. The second specimen, the paratype IGM 100/51 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.[1] In 2008, Dr. Thomas R. Holtz, JR. estimated its lenght around 1.8 m (5.9 ft) long and a weight comparable to a beaver.[2]

Classification

Adasaurus is a member of Dromaeosauridae, a group that is closely related to living birds. Other dromaeosaurids include Deinonychus, Velociraptor, Microraptor, and Buitreraptor. The relationships of Adasaurus are poorly understood. Traditionally, Adasaurus is assigned to the Dromaeosaurinae, which includes heavily built animals such as Achillobator and Utahraptor [3][4] but several recent studies have suggested that it may be a member of the Velociraptorinae instead.[5][6]

Below is a cladogram based on the phylogenetic analysis, conducted by Andrea Cau et al. in 2017.[7]

Eudromaeosauria

Bambiraptor

Tianyuraptor

Dromaeosaurinae

Achillobator

Utahraptor

Dromaeosaurus

Velociraptorinae

Adasaurus

Deinonychus

Saurornitholestes

Velociraptor

Tsaagan

Linheraptor

Paleoecology

The age of the Nemegt Formation is not known for certain, but it is commonly thought to belong to the Maastrichtian stage of the Late Cretaceous Period.[8] Dr. Thomas R. Holtz, JR. estimated that Adasaurus lived between 70.6 and 68.5 million years ago.[2] Other dinosaurs found in this formation include the famous tyrannosaur Tarbosaurus, the ornithomimid Anserimimus, the troodontid Zanabazar, and the hadrosaur Saurolophus.[9]

See also

References

  1. ^ a b c Barsbold, R. (1983). "Carnivorous Dinosaurs from the Cretaceous of Mongolia". Transactions of the Joint Soviet-Mongolian Paleontological Expedition. 19: 5–119.
  2. ^ a b Holtz, T. R.; Rey, L. V. (2007). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. Random House. Supplementary Information
  3. ^ Norell, Mark A.; Peter J. Makovicky (2004). "Dromaeosauridae". In David B. Weishampel, Peter Dodson and Halszka Osmólska (eds.). The Dinosauria (2nd ed.). Berkeley, California: University of California Press. pp. 196–209. ISBN 0-520-24209-2. OCLC 55000644. Retrieved 24 May 2009.CS1 maint: uses editors parameter (link)
  4. ^ Makovicky, Peter J.; Sebastián Apesteguía; Federico L. Agnolín (2005). "The earliest dromaeosaurid theropod from South America". Nature. 437 (7061): 1007–1011. Bibcode:2005Natur.437.1007M. doi:10.1038/nature03996. PMID 16222297.
  5. ^ Senter, P.; Kirkland, J. I.; Deblieux, D. D.; Madsen, S.; Toth, N. (2012). Dodson, Peter (ed.). "New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail". PLoS ONE. 7 (5): e36790. doi:10.1371/journal.pone.0036790. PMC 3352940. PMID 22615813.
  6. ^ Longrich, N. R.; Philip, J. C. (2009). Kennett, J. P. (ed.). "A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America". Proceedings of the National Academy of Sciences. 106 (13): 5002–7. doi:10.1073/pnas.0811664106.
  7. ^ Cau, A.; Beyrand, V.; Voeten, D.; Fernandez, V.; Tafforeau, P.; Stein, K.; Barsbold, R.; Tsogtbaatar, K.; Currie, P.; Godrfroit, P. (6 December 2017). "Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs". Nature. 552 (7685): 395–399. Bibcode:2017Natur.552..395C. doi:10.1038/nature24679. PMID 29211712.
  8. ^ Jerzykiewicz, T.; D.A. Russell (August 1991). "Late Mesozoic stratigraphy and vertebrates of the Gobi Basin". Cretaceous Research. 12 (4): 345–446. doi:10.1016/0195-6671(91)90015-5.
  9. ^ Weishampel, D. B.; Dodson, P.; Osmolska, H. (2007). The Dinosauria, Second Edition. University of California Press. p. 596.


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