Zhou and Hou (2001) distinguish Cathayornis from Sinornis by the former's larger size, a shorter, straighter, finger number I, with a slightly longer claw (ungual), the absence of an atitrochanter, and other features. They give Cathayornis one species name, Cathayornis yandica.[2]
Sereno et al. (2001) see Cathayornis as a junior synonym of Sinornis. They interpret the anatomies of the two as very similar and sharing key autapomorphies of the pygostyle. They give Sinornis one species name, Sinornis santensis.[3]
References
^ Swisher, Carl C., Wang, Yuan-qing, Wang, Xiao-lin, Xu, Xing, Wang, Yuan. (1999). "Cretaceous age for the feathered dinosaurs of Liaoning, China". Nature 400:58-61 1 July 1999.
^ Zhou, Zhonghe, Hou, Lianhai (2001) "The Discovery and Study of Mesozoic Birds in China" in "Mesozoic Birds: above the heads of dinosaurs". Chiappe and Witmer, ed. 2001, University of California Press
^ Sereno, Paul, Chenggang, Rao, Li, Jianjun. (2001) "Sinornis santensis (Aves:Enantiornithes) from the Early Cretaceous of Northeastern China". in "Mesozoic Birds: above the heads of dinosaurs". Chiappe and Witmer, ed. 2001, University of California Press