There is currently a dispute regarding the correct name for this enantiornithine bird, which may be Sinornis or Cathayornis. In any case, several referred fossils were recovered from the Jiufotang Formation at Liaoning, People's Republic of China. The Jiufotang overlays the Yixian, which suggests an Aptian or Albian age (between 100-120 million years old), according to Swisher et al. (1999).
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.
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.
Early evolution of avian flight and perching: new evidence from the Lower Cretaceous of China. (Sinornis santensis)
Feb 14, 1992; THE SKELETON OF THE OLDEST BIRD, Archaeopteryx, is characterized by elongate grasping forelimbs and a long balancing tail, and...
Evolutionists wing it with a new fossil bird: sparrow-sized bird skeletons from an Early Cretaceous lake bed in China provide clues to the evolution of flight. (Sinoris)
Feb 14, 1992; MOST OF WHAT SCIENTISTS KNOW ABOUT THE origin of birds comes from Archaeopteryx, the 150-million-year-old fossil with its odd mix...