Hongshanornithidae is an extinct group of early

ornithuromorph Euornithes (from Greek ' meaning "true birds") is a natural group which includes the most recent common ancestor of all avialans closer to modern birds than to ''Sinornis''. Description Clarke ''et al''. (2006) found that the most primitive know ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s from the early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

period of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. It includes the

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

Hongshanornis ''Hongshanornis'' is a genus of ornithuromorph birds known from early Cretaceous lake deposits of the Yixian Formation, Inner Mongolia, China. The holotype specimen, recovered in 2005, is currently held by the Institute of Vertebrate Paleontology ...

'' (the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...

) and '' Tianyuornis'' from the

Yixian Formation The Yixian Formation (; formerly transcribed as Yihsien Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the late Barremian and early Aptian stages of the Early Cretaceous. It is known for its ex ...

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a ...

, ''

Longicrusavis ''Longicrusavis'' (meaning "long shin bird" in Latin) is an extinct genus of basal ornithuromorph bird found only at Dawangzhangzi village in Liaoning Province, China. ''Longicrusavis'' was a ground dwelling carnivore, a wader, and part of biol ...

'' from the Yixian Formation of

Liaoning Province Liaoning () is a coastal provinces of China, province in Northeast China that is the smallest, southernmost, and most populous province in the region. With its capital at Shenyang, it is located on the northern shore of the Yellow Sea, and i ...

, '' Parahongshanornis'' from the

Jiufotang Formation The Jiufotang Formation (Chinese: 九佛堂组, pinyin: ''jiǔfótáng zǔ'') is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms (see ...

of Liaoning Province, and ''

Archaeornithura ''Archaeornithura'' is an extinct genus of ornithuromorphs from the early Cretaceous period. It is known from two fossil specimens of a single species, ''Archaeornithura meemannae''. The specimens have been dated to the Hauterivian age, 130.7 mil ...

'', the oldest known member, from the

Huajiying Formation The Huajiying Formation is a geological formation in Hebei, People's Republic of China. Known for its fossils including feathered dinosaurs, the age of the formation is uncertain. It may represent an early portion of the Jehol Biota, dating to som ...

Hebei Province Hebei or , (; alternately Hopeh) is a northern province of China. Hebei is China's sixth most populous province, with over 75 million people. Shijiazhuang is the capital city. The province is 96% Han Chinese, 3% Manchu, 0.8% Hui, an ...

Description

Hongshanornithids were small, approximately the size of modern phoebes. Their legs are proportionally long in comparison to the wings, suggesting that they were aquatic wading birds. They most likely lacked beaks and had teeth in their jaws.

Classification

Hongshanornithidae was defined as a node-based clade including the last common ancestor of ''Hongshanornis longicresta'' and ''Longicrusavis houi'' plus all its descendants. Beginning in 2012, several studies began to find that the hongshanornithids were more closely related to

songlingornithids Songlingornithidae is a family of basal euornitheans from the Early Cretaceous of China. All known specimens come from the Jiufotang Formation and the Yixian Formation, dating to the early Barremian and Aptian ages, 125–120 million years ag ...

(yanornithiformes) than to other early birds, making them part of the same clade.

References

Early Cretaceous birds of Asia Early Cretaceous first appearances Early Cretaceous extinctions Prehistoric dinosaur families {{paleo-bird-stub