''Paraprotopteryx'' is a genus of

enantiornithean 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 ...

birds from the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

of China.Zheng, X. Zhang, Z. & Hou, L. (2007) A new enantiornithine bird with four long rectrices from the Early Cretaceous of northern Hebei, China. ''Acta Geologica Sinica'' 81(5):703-708. In 2007, the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

''Paraprotopeteryx gracilis'' was named and described by Zheng Xiaoting, Zhang Zihui and Hou Lianhai. The generic name means "near '' Protopteryx''", in reference to a presumed similarity with that genus. The specific name is intended to mean "pretty". The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

is specimen STM V001. It consists of a skeleton with skull on a plate and counterplate. The investigation preceding the description of the species proved that fossil traders had added the skull of a different individual to the torso. The description is based on the rump parts. Feathers have been preserved. The rump represents a subadult individual. Though initially reported to be from the Early Cretaceous

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 exq ...

, later investigation showed that the fossil actually came from the Qiaotou Member of 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 s ...

Fengning Fengning Manchu Autonomous County (; Manchu: ; Mölendroff: fengning manju beye dasangga siyan) is a Manchu autonomous county of northern Hebei province, bordering Beijing to the southwest and Inner Mongolia to the north, and lying under the admin ...

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, and 0 ...

, China, and is therefore of uncertain age. While much of the Huajiying Formation underlies the Yixian Formation,Jin, Zhang, Li, Zhang, Li and Zhou (2008). "On the horizon of ''Protopteryx'' and the early vertebrate fossil assemblages of the Jehol Biota." ''Chinese Science Bulletin'', 53(18): 2820-2827. Ji and colleagues suggested in 2008 that the Qiaotou Member correlates with the Dawangzhangzi beds of the Yixian Formation, dated to approximately 122 million years ago by

Zhou Zhonghe Zhou Zhonghe (; born 19 January 1965 in Jiangdu, Jiangsu province) is a Chinese palaeontologist. He described the ancient bird ''Confuciusornis''.. Zhou graduated from Nanjing University and earned a Ph.D. in Biology in 1999 from the University o ...

in 2006.Zhou, Z. (2006). "Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives." ''Geological Journal'', 41: 377–393.

Distinguishing characteristics

The original description suggested a number of distinguishing traits. ''Paraprotopteryx'' would have had a

furcula The (Latin for "little fork") or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two pink clavicles. In birds, its primary function is in the strengthening of the thoracic ...

(wishbone) which is shaped like a Y with a narrow angle between the clavicles. It also was described as having an unusually shaped breastbone, distinguishing it from other birds in the

Enantiornithines 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 ...

. The

carpometacarpus The carpometacarpus is a bone found in the hands of birds. It results from the fusion of the carpal and metacarpal bone, and is essentially a single fused bone between the wrist and the knuckles. It is a smallish bone in most birds, generally flat ...

is only partially fused. ''Paraprotopteryx'' has four, ten centimetres long,

rectrices Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...

(flight feathers on the tail), more than doubling the total body length, which may represent an important step in feather evolution. They have a very elongated ribbon-like shaft and only the tips are barbed and expanded. In ''Paraprotopteryx'' they may have served as a secondary sex characteristic. This was the first time a tail fan was reported for Enantiornithes. Later such a double pair was reported for ''

Shanweiniao ''Shanweiniao'' is a genus of long-snouted enantiornithean birds from Early Cretaceous China. One species is known, ''Shanweiniao cooperorum''. There is one known fossil, a slab and counterslab. The fossil is in the collection of the Dalian ...

''. However, although the presence of two ribbon-like rectrices is certain (as in the related enantiornithean bird ''Protopteryx'') the describers of ''Shanweiniao'' in 2012 voiced a suspicion that the second pair of rectrices in ''Paraprotopteryx'' might be the result of artifice.Jingmai K. O’Connor, Luis M. Chiappe, Cheng-ming Chuong, David J. Bottjer and Hailu You (2012) "Homology and Potential Cellular and Molecular Mechanisms for the Development of Unique Feather Morphologies in Early Birds." ''Geosciences'', 2 157-177.

References

External links

A photograph of the main slab of the type specimen (STM V001), published by Albertonykus's (Albert Chen's) twitter account
Early Cretaceous birds of Asia Enantiornitheans Fossil taxa described in 2007 {{paleo-bird-stub