QIN Zi-Chuan, ZHAO Qi & XU Xing (2019)
Metatarsal II osteohistology of Xixianykus zhangi (Theropoda: Alvarezsauria) and its implications for the development of the arctometatarsalian pes.
Vertebrata PalAsiatica (advance online publication)
The late-branching alvarezsaurian Xixianykus zhangi is among the smallest known non-avialan theropods. With great similarity to its close relatives, it is highly cursorial as indicated by proportionally long lower segments of the hindlimbs and the presence of an arctometatarsalian pesâa highly modified structure that has been suggested to improve cursorial capability in theropods. Here we describe the osteohistology of the metatarsal II of the holotype of X. zhangi (XMDFEC V 0011). Two rarely reported histological features, radial vascular canals and Sharpeyâs fibers, are presented in this study. We suggest that both features are related to the development of the arctometatarsalian pes; however, further investigations of metatarsal osteohistology in theropods are required for the validation of our interpretation.Â