Xiaotingia

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Xiaotingia
Temporal range: Late Jurassic, 160Ma
Xiaotingia fossil.jpg
Type specimen
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Suborder: Theropoda
Superfamily: Dromaeosauroidea
Family: Dromaeosauridae
Genus: Xiaotingia
Xu et al., 2011
Species: † X. zhengi
Binomial name
Xiaotingia zhengi
Xu et al., 2011

Xiaotingia is a genus of bird-like theropod dinosaur from early Late Jurassic deposits of western Liaoning, China, containing a single species, Xiaotingia zhengi.[1]

Discovery[edit]

Size of Xiaotingia

Xiaotingia is known from the holotype STM 27-2, an articulated and almost complete skeleton including the skull. It was probably collected in the Linglongta area, Jianchang, from the Tiaojishan Formation.[1]

Etymology[edit]

Xiaotingia was first named by Xu Xing, You Hailu, Du Kai and Han Fenglu in 2011 and the type species is Xiaotingia zhengi. The generic name and specific name together honour Zheng Xiaoting.[1]

Classification[edit]

The initial analysis by Xu et al. showed that Xiaotingia formed a clade with Archaeopteryx, Dromaeosauridae and Troodontidae to the exclusion of other groups traditionally seen as birds. Xu et al therefore (re)defined the concepts of Deinonychosauria and Avialae to the extent that Archaeopteryx and Xiaotingia belonged to the Deinonychosauria in the clade Archaeopterygidae.[1] This led to popular reports that "Archaeopteryx is no longer a bird",[2] although Xu et al noted that there are several competing definitions of the clade Aves currently in use, pointing out that their definitions are compatible with a traditional Aves with Archaeopteryx as a specifier.[1] This was challenged by an analysis using different methods published several months later however, in which Archaeopteryx was again recovered as an avialan, while Xiaotingia remained closely allied to Anchiornis within the Troodontidae.[3] In 2012, an expanded and revised version of the initial analysis also found Archaeopteryx to be avialan and Anchiornis to be troodontid, but recovered Xiaotingia as the most primitive member of the clade Dromaeosauridae rather than a close relative of Anchiornis within Troodontidae.[4]

Life restoration
Skeletal restoration

Relationships found by the revised analysis of Senter et al., 2012:[4]

Paraves

Avialae


Deinonychosauria

Troodontidae


Dromaeosauridae

Xiaotingia




Unenlagiinae




Shanag




Microraptoria



Eudromaeosauria








Relationships found by the initial analysis of Xu et al., 2011:[1]

Paraves

Avialae


Deinonychosauria


Troodontidae



Dromaeosauridae



Archaeopterygidae


Archaeopteryx



Wellnhoferia





Anchiornis



Xiaotingia






References[edit]

  1. ^ a b c d e f Xing Xu, Hailu You, Kai Du and Fenglu Han (28 July 2011). "An Archaeopteryx-like theropod from China and the origin of Avialae". Nature 475 (7357): 465–470. doi:10.1038/nature10288. PMID 21796204. 
  2. ^ "Feathers fly in first bird debate". BBC News. 27 July 2011. 
  3. ^ Lee, M.S.Y. and Worthy, T.H. (2011). "Likelihood reinstates Archaeopteryx as a primitive bird. Biology Letters, published online before print October 26, 2011, doi:10.1098/rsbl.2011.0884
  4. ^ a b Senter, P., Kirkland, J.I., DeBlieux, D.D., Madsen, S., and Toth, N. (2012). "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 PMID 22615813