A basal parvicursorine (Theropoda: Alvarezsauridae) from the Upper Cretaceous of China

Xing Xu*, De-You Wang, Corwin Sullivan, David W. E. Hone, Feng-Lu Han, Rong-Hao Yan, Fu-Ming Du

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

31 Citations (Scopus)


A new alvarezsaurid theropod, Xixianykus zhangi gen. et sp. nov., is described based on a partial postcranial skeleton collected from the Upper Cretaceous Majiacun Formation of Xixia County, Henan Province. The new taxon can be diagnosed by the following autapomorphies: sacral rib-transverse process complexes and zygapophyses fused to form separate anterior and posterior laminae; distinct fossa dorsal to antitrochanter on lateral surface of ilium; short ridge along posterior surface of pubic shaft near proximal end; distinct depression on lateral surface of ischium near proximal end; sharp groove along posterior surface of ischium; distal end of femur with transversely narrow ectocondylar tuber that extends considerable distance proximally as sharp ridge; transversely narrow tibial cnemial crest with sharp, ridgelike distal half; lateral margin of tibiotarsus forms step near distal end; fibula with substantial extension of proximal articular surface onto posterior face of posteriorly curving shaft; distal tarsals and metatarsals co-ossified to form tarsometatarsus; and sharp flange along anteromedial margin of metatarsal IV near proximal end. Cladistic analysis places this taxon as a basal parvicursorine within the Alvarezsauridae, a position consistent with the presence of several incipiently developed parvicursorine features in this taxon and also with its relatively early geological age. A brief analysis of vertebral functional morphology, together with data from the hindlimb, suggests that parvicursorines represent extreme cursors among non-avian dinosaurs.

Original languageEnglish
Pages (from-to)1-19
Number of pages19
Issue number2413
Publication statusPublished - 29 Mar 2010


  • Late Cretaceous
  • Majiacun Formation
  • Parvicursorinae
  • Theropoda
  • cursoriality


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