''Xunmenglong'' (from ) is a genus of

compsognathid Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other d ...

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 ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

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 ...

from

Hebei Province Hebei is a Provinces of China, province in North China. It is China's List of Chinese administrative divisions by population, sixth-most populous province, with a population of over 75 million people. Shijiazhuang is the capital city. It bor ...

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 Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

and only species is ''Xunmenglong yinliangis''. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

material consists of a pelvis, tail base and hindlimbs that had previously been part of a

chimera Chimera, Chimaera, or Chimaira (Greek for " she-goat") originally referred to: * Chimera (mythology), a fire-breathing monster of ancient Lycia said to combine parts from multiple animals * Mount Chimaera, a fire-spewing region of Lycia or Cilicia ...

containing three different animals. The animal is described as being the smallest known member of Compsognathidae, being about the size of the sub-adult ''

Scipionyx ''Scipionyx'' ( ) was a genus of theropod dinosaur from the Early Cretaceous Pietraroja Formation of Italy, around 113 mya (unit), million years ago. There is only one fossil known of ''Scipionyx'', discovered in 1981 by an amateur paleontolog ...

'' holotype specimen or approximately 0.5 meters (1.6 feet) in length.

Classification

In the original description, ''Xunmenglong'' is recovered as a

in a polytomy including ''

Compsognathus ''Compsognathus'' (; Ancient Greek, Greek ''kompsos''/κομψός; "elegant", "refined" or "dainty", and ''gnathos''/γνάθος; "jaw") is a genus of small, bipedalism, bipedal, carnivore, carnivorous theropoda, theropod dinosaur. Members o ...

'', ''

Huaxiagnathus ''Huaxiagnathus'' is an extinct genus of coelurosaurian theropod dinosaur from the Lower Cretaceous of China. The genus contains a single species, ''Huaxiagnathus orientalis'', known from two immature individuals from the Yixian Formation. ''Hua ...

'' and ''

Juravenator ''Juravenator'' is a genus of small (75 cm long) coelurosaurian theropod dinosaur (although a 2020 study proposed it to be a hatchling megalosauroid), which lived about 151 or 152 million years ago in the area that would someday become the ...

''. However, Andrea Cau (2024) recovered ''Xunmenglong'' not as a compsognathid, but instead as a basal member of

Tetanurae Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most Theropoda, theropod dinosaurs, including Megalosauroidea, megalosauroids, Allosauroidea, allosauroids, and Coelurosauria, coelurosaurs (which includes Tyrannosauroi ...

References

Compsognathidae Dinosaur genera Hauterivian dinosaurs Dinosaurs of China Fossil taxa described in 2019 Taxa named by Philip J. Currie {{Theropod-stub