''Xixianykus'' is a genus of alvarezsaurid theropod dinosaur from the late Cretaceous period of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

.Xu, X., Wang, D.Y., Sullivan, C., Hone, D.W.E., Han, F.L., Yan, R.H. and Du, F.M. (2010). "A basal parvicursorine (Theropoda: Alvarezsauridae) from the Upper Cretaceous of China.". ''Zootaxa'', 2413: 1-19.

Discovery and naming

The fossil, holotype XMDFEC V0011, was found in the Majiacun Formation in Henan Province,

. The fossil consists of a partial skeleton, without the skull. Parts of the hind legs, pelvis and spine has also been recovered. ''Xixianykus'' is among the oldest of the derived alvarezsauroids, the parvicursorines, dated to the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The ...

–

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...

, as opposed to other parvicursorines, which are either Campanian or Maastrichtian.Hone, D. (2010)
''Xixianykus zhangi'' - A New Alvarezsaur
Dave Hone's Archosaur Musings, April 23, 2011. The type species is ''Xixianykus zhangi'' described in 2010 by Xu Xing. The genus name refers to Xixia County and to the Greek word for claw ("''onyx''"). The latter is a common element used in names for Alvarezsaurids. The species name is in honor of Zhang Xinglao.

Description

''Xixianykus'' was a small animal, about long and high. It is one of the smallest-known dinosaurs (not counting

avians Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

). It appears to have many adaptations towards a

cursorial A cursorial organism is one that is adapted specifically to run. An animal can be considered cursorial if it has the ability to run fast (e.g. cheetah) or if it can keep a constant speed for a long distance (high endurance). "Cursorial" is often u ...

(running) lifestyle. It was about 50 centimetres long but had legs and a short femur combined with a long tibia and metatarsus, which are good indicators of it being a fast runner. It was probably covered in

feather Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier ...

References

External links

Agile 'roadrunner' dinosaur fossil discovered in China
Alvarezsaurids Late Cretaceous dinosaurs of Asia Fossil taxa described in 2010 Taxa named by Xu Xing {{Theropod-stub