''Liaoxiornis'' is a dubious

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

enantiornithine The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

bird. The only named species is ''Liaoxiornis delicatus'', described by Hou and Chen in 1999.Hou, L., Chen, P.-J. (1999) "Liaoxiornis delicatus gen. et sp. nov., the smallest Mesozoic bird. Chinese Science Bulletin 44(9):834-838. Because the species was named for a hatchling specimen, it cannot be matched with adult specimens, and so it is impossible to determine which, if any, birds from the same rocks represent adults of this species.

Luis Chiappe Luis María Chiappe (born 18 June 1962) is an Argentine paleontologist born in Buenos Aires who is best known for his discovery of the first sauropod nesting sites in the badlands of Patagonia in 1997 and for his work on the origin and early evo ...

and colleagues therefore regarded it as a ''nomen vanum'' ("empty name") or at least a ''nomen dubium'', and recommended that use of the name be abandoned.Chiappe, L.M., Ji S. and Ji Q. (2007). "Juvenile Birds from the Early Cretaceous of China: Implications for Enantiornithine Ontogeny." ''American Museum Novitates'', 3594: 46pp. Liaoxiornis delicatus 3

History

In 1999, Hou and Chen of the Nanjing Institute of Paleontology and Geology briefly described a specimen of very small bird obtained by the museum and named it ''Liaoxiornis delicatus''. One month later, another specimen, obtained by the National Geological Museum of China (

Beijing } Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...

), was named by Li and Li as ''Lingyuanornis parvus''.Ji, Qiang, Ji, S.-A. (1999) "A new genus of the Mesozoic birds from Lingyuan, Liaoning, China". "Chinese Geology" 262:45-48. Soon afterwards, it was found that both museums had obtained different slabs of exactly the same specimen; because ''Liaoxiornis delicatus'' was named slightly earlier, that name takes precedence.Chiappe, Luis, Walker, Cyril A. (2001) "Euenantiornithes" in "Mesozoic Birds: above the heads of dinosaurs". Chiappe and Witmer, ed. 2001, University of California Press The type specimen is complete and articulated, and while it has mature flight feathers, features such as bones tipped in cartilage, small breastbone, large head and eye and unfused skeleton indicate that it was a juvenile. Zhou and Hou (2001) assigned it to the group

Enantiornithes The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

, and described it as being equally as advanced as ''

Cathayornis ''Cathayornis'' is a genus of enantiornithean 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 Enantiornithes found in China. Se ...

''.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 Several other specimens of juvenile enantiornithines have been found in the same strata, but because all of them are juveniles, it is impossible to discern whether or not they represent the same species, and later authors have suggested that the taxon should be ignored as invalid for this reason.

References

Enantiornitheans Bird genera Early Cretaceous birds of Asia Prehistoric animals of China Nomina dubia Fossil taxa described in 1999 {{paleo-bird-stub