''Graciliraptor'' (meaning "graceful thief") is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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 early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Period. It is a microraptorine

dromaeosaurid Dromaeosauridae () is a family (biology), family of feathered coelurosaurian Theropoda, theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous period (geology), Period. The name Drom ...

. The

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

''Graciliraptor lujiatunensis'' was first named and described in 2004 by Xu Xing and Wang Xiaoling. The generic name is derived from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''gracilis'' and ''raptor''. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

refers to the village Lujiatun where the fossil site is located. Its

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

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 ...

IVPP V 13474, was found in

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 ...

Liaoning Province ) , 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 ...

Description

The type and only known specimen comprised part of the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

with some teeth, nearly complete fore and hind legs; and ten partial tail vertebrae. It is estimated to have been about long in life.Holtz, Thomas R. Jr. (2011) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'
Winter 2010 Appendix.
/ref> In 2010,

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...

gave higher estimations of one metre and 1.5 kilogrammes. ''Graciliraptor'' is extremely lightly built for a non-avian theropod, with very elongated middle caudal vertebrae and lower leg bones. The

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

is thirteen centimetres long and total body length was estimated at one metre. The posterior

articular process The articular process or zygapophysis ( + apophysis) of a vertebra is a projection of the vertebra that serves the purpose of fitting with an adjacent vertebra. The actual region of contact is called the ''articular facet''.Moore, Keith L. et al. ...

es of the tail vertebrae, or postzygapophyses, are connected by a thin bone sheath or lamina, that extends to the back over an eighth of the centrum of the following vertebra, thus further stiffening the middle tail, already immobilised by the typical dromaeosaurid long

prezygapophyses The articular process or zygapophysis ( + apophysis) of a vertebra is a projection of the vertebra that serves the purpose of fitting with an adjacent vertebra. The actual region of contact is called the ''articular facet''.Moore, Keith L. et al. ...

.Xu, X. and Wang, X.-L. (2004). "A New Dromaeosaur (Dinosauria: Theropoda) from the Early Cretaceous Yixian Formation of Western Liaoning." ''Vertebrata PalAsiatica'', 42(2): 11-119. ''Graciliraptor'' has been found in the lowest portions of the

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 ...

, the Lujiatun Member, below the rocks where similar early dromaeosaurids (such as ''

Sinornithosaurus ''Sinornithosaurus'' (derived from a combination of Latin and Ancient Greek, Greek, meaning 'Chinese bird-lizard') is a genus of Feathered dinosaurs, feathered dromaeosaurid dinosaur from the early Cretaceous Period (geology), Period (late Barrem ...

'' and ''

Microraptor ''Microraptor'' (Greek language, Greek, μικρός, ''mīkros'': "small"; Latin language, Latin, ''raptor'': "one who seizes") is a genus of small, four-winged dromaeosaurid dinosaurs. Numerous well-preserved fossil specimens have been recovere ...

'') were found. It is, in geological age, the oldest named dromaeosaurid, and the oldest known from good fossil remains (dromaeosaurid fossils date back all the way to the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

, but consist mostly of teeth).

Classification

As an early dromaeosaurid, ''Graciliraptor'' provided information on the early evolution and diversification of the group. It shares several characteristics in common with both early troodontids and avialan birds, supporting a close relationship between avialans, troodontids, and dromaeosaurids. Xu and Wang considered ''Graciliraptor'' to have been closely related to ''

'', a similar

from the slightly younger

Jiufotang Formation The Jiufotang Formation () is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms (see Jehol Biota). It is a member of the Jehol group. T ...

. Later it was placed in the Microraptorinae.F. Knoll and J. I. Ruiz-Omeñaca. 2009. "Theropod teeth from the basalmost Cretaceous of Anoual (Morocco) and their palaeobiogeographical significance". ''Geological Magazine'' 146(4): 602-616

References

External links

A New Dromaeosaur (Dinosauria: Theropoda) from the Early Cretaceous Yixian Formation of Western Liaoning.
{{Taxonbar, from=Q134623 Microraptoria Dinosaur genera Barremian dinosaurs Yixian Formation Taxa named by Xu Xing Fossil taxa described in 2004 Dinosaurs of China

Description

Classification

See also

References

External links