''Beipiaognathus'' (meaning

Beipiao Beipiao () is a city in Chaoyang prefecture, Liaoning province, in Northeast China. It has a population of 202,807. The main industry in the area is coal mining. With vertical shafts of almost 1000m, these are some of the deepest coal mines in C ...

jaw) is a dubious genus of

coelurosauria Coelurosauria (; from Greek, meaning "hollow-tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyra ...

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

from the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

Yixian Formation The Yixian Formation (; formerly Romanization of Chinese, transcribed as Yihsien Formation or Yixiang Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the Barremian stage of the Early Cretaceous. I ...

Liaoning ) , image_skyline = , image_alt = , image_caption = Clockwise: Mukden Palace in Shenyang, Xinghai Square in Dalian, Dalian coast, Yalu River at Dandong , image_map = Liaoning in China (+all claims hatched).svg , ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. The type species is ''Beipiaognathus jii'' and it was named and described by Hu ''et al.'' in 2016. The genus was initially assigned to the

Compsognathidae Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Period (geology), Periods. The bird-like features of these species, a ...

by Hu ''et al.'' (2016) based on the presence of two traits: fan-shaped dorsal neural spines and a robust I-1

phalanx The phalanx (: phalanxes or phalanges) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar polearms tightly packed together. The term is particularly used t ...

on the hand. However, it also differs from other compsognathids in several ways: the teeth are unserrated and conical; the ulna is proportionally longer; the II-1 phalanx on the hand is longer and more robust; and the tail is much shorter. However, Andrea Cau informally noted a number of points in the fossil that are indicative of it having been artificially assembled, thus rendering the specimen a phylogenetically uninformative chimaera. Additionally, he argued that the characters cited are not unique to compsognathids, with fan-shaped neural spines being also seen in

ornithomimosaurs Ornithomimosauria ("bird-mimic lizards") are theropod dinosaurs which bore a superficial resemblance to the modern-day ostrich. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period (geology), Period of Laurasia (now Asia ...

and the

troodontid Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinos ...

Sinovenator ''Sinovenator'' (meaning "Chinese hunter") is a genus of troodontid dinosaur from China. It is from the early Cretaceous Period (geology), Period. Discovery and naming Two specimens of a troodontidae, troodontid were described in 2002 in paleo ...

'', and the robust I-1 phalanx also being seen in

alvarezsaurids Alvarezsauridae is a family of small, long-legged dinosaurs. Although originally thought to represent the earliest known flightless birds, they are now thought to be an early diverging branch of maniraptoran theropods. Alvarezsaurids were highly ...

. He also argued that in one case, there has been reportedly found a coracoid in the tail, but maybe that was the way it died, or it belonged to another dinosaur separate from ''Beipiaognathus''. The chimeric status of ''Beipiaognathus'' was noted in the literature for the first time by Xing ''et al.'' in 2020, in their description of '' Xunmenglong''.

References

{{Taxonbar, from=Q26722479 Compsognathidae Dinosaur genera Barremian dinosaurs Yixian Formation Fossil taxa described in 2016 Dinosaurs of China