Cathayornis

Cathayornis Temporal range: Early Cretaceous, 120 Ma PreЄ Є O S D C P T J K Pg N ↓
Skull reconstruction of C. yandica
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	†Enantiornithes
Clade:	†Euenantiornithes
Genus:	†Cathayornis Zhou, Jin & Zhang, 1992
Type species
†Cathayornis yandica Zhou et al., 1992
Other Species
†C. aberransis? Hou et al., 2002 †C. chabuensis? Li et al., 2008

Cathayornis is a genus of enantiornithine birds from the Jiufotang Formation of Liaoning, People's Republic of China. It is known definitively from only one species, Cathayornis yandica, one of the first enantiornithines found in China. Several additional species were once incorrectly classified as Cathayornis, and have since been reclassified or regarded as nomina dubia.

Cathayornis yandica was a small enantiornithine with a slightly elongated, toothy snout and perching feet. Like most other enantiornithines, it had large claws on the first two fingers that supported the wing. According to most recent studies, only one specimen can be definitively assigned to this species, a fossil catalogued as number IVPP V9769 and currently housed in the collections of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.Cathayornis can be told apart from similar enantiornithines (especially Sinornis, Eocathayornis, and Houornis) by its larger size, a shorter and straighter first finger with a slightly longer claw, and other anatomical details. Two additional but very fragmentary specimens, IVPP V9936 and V10896, have been referred to C. yandica in the past, but cannot be directly compared with the type specimen because they do not preserve any of the same key parts of the skeleton.

Paul Sereno et al., in 2002, considered Cathayornis a junior synonym of Sinornis. They interpreted the anatomies of the two as very similar and sharing key autapomorphies of the pygostyle. The first thorough review of Sinornis and Cathayornis was published by Jingmai O'Connor and Gareth Dyke in 2010. O'Connor and Dyke concluded that despite the earlier opinion of Sereno and colleagues, the two birds were not synonyms and in fact differ in several clear ways, including different proportions in the wing claws and digits, differences in the pelvis, and size of the pygostyle.