''Xinjiangovenator'' (meaning "

Xinjiang Xinjiang,; , SASM/GNC romanization, SASM/GNC: Chinese postal romanization, previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an Autonomous regions of China, autonomous region of the China, People' ...

hunter") 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 ...

of coelurosaurian

dinosaurs 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 ...

, possibly part of the group

Maniraptora Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Dromaeosauridae, Troodontidae, ...

, which lived during 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 ...

period, sometime between the

Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 137.05 ± 0.2 Ma and 132.6 ± 0.2 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretac ...

and

Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...

stages.

Discovery

The remains of ''Xinjiangovenator'' were found in the Lianmuqin Formation of Wuerho,

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 ...

, and were first described by

Dong Zhiming Dong Zhiming (Chinese language, Chinese: 董枝明, Pinyin: ''Dǒng Zhimíng''; January 1937 – 20 October 2024) was a Chinese vertebrate paleontologist formerly employed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) ...

in 1973. The genus is based on a single specimen, an articulated partial right lower leg, containing the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

, three pieces of the

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

, the

calcaneum In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel; : calcanei or calcanea) or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is t ...

and the

astragalus Astragalus may refer to: * ''Astragalus'' (plant), a large genus of herbs and small shrubs *Astragalus (bone) The talus (; Latin for ankle or ankle bone; : tali), talus bone, astragalus (), or ankle bone is one of the group of foot bones known ...

. This specimen, IVPP V4024-2, is 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 ...

of the genus. The holotype was originally thought to be another specimen of '' Phaedrolosaurus''. However, ''Phaedrolosaurus'' is based only on a non-diagnostic tooth, so the hindlimb bones were given their own genus by Oliver Rauhut and Xu Xing in 2005. 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 ...

is ''Xinjiangovenator parvus''. The generic name is derived from the autonomous region of Xinjiang and

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 ...

''venator'', "hunter". The specific name ''parvus'' means "small" in Latin. The lower leg (tibia plus ankle bones) has a length of 312 millimeters (12.3 inches). Gregory S. Paul estimated in 2010 that ''Xinjiangovenator'' individuals had a length of 3 meters and a mass of 70 kg. Paul, G. S. (2010). '' The Princeton Field Guide to Dinosaurs''. Princeton University Press, p. 100. Rauhut & Xu (2005) established two autapomorphies (unique derived traits) that could be used to characterize ''Xinjiangovenator''. First, the lateral condyle (outer ankle joint) at the lower end of the tibia extends further backwards than the outer edge of the portion of the tibia near the knee. Secondly, the proximal part of the fibula (near the knee) has a longitudinal groove along its front edge.

Classification

Rauhut & Xu (2005) originally placed ''Xinjiangovenator'' within the coelurosaur subgroup

using a phylogenetic analysis. It was considered to be more closely related to paravians such as dromaeosaurids and

birds Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

, rather than oviraptorosaurians and

therizinosaurs Therizinosaurs (; once called segnosaurs) are an extinct group of large herbivorous theropod dinosaurs whose fossils have been mainly discovered from Cretaceous deposits in Asia and North America. Potential fragmentary remains have also been foun ...

. This placement was justified by the presence of a tall and wide ascending process of the astragalus bone. In addition, the fibular condyle of the femur expanded backwards and the fibula tapered drastically towards the ankle. These characteristics were also found to be present in the coelurosaur '' Bagaraatan,'' and Rauhut & Xu (2005) suggested that ''Xinjiangovenator'' and ''Bagaraatan'' were

sister taxa In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

. The 2010 description of '' Zuolong'' by Jonah Choiniere, James M. Clark, Catherine Forster, & Xu Xing found a different position for ''Xinjiangovenator'' in their phylogenetic analysis. Due to its fragmentary nature, ''Xinjiangovenator'' was found to have an unstable position within Coelurosauria. Some, but not all, of the phylogenetic trees found ''Xinjiangovenator'' as the sister taxon to '' Ornitholestes'' based on the proximal part of the tibia being just as wide along its front edge as its rear edge. When ''Xinjiangovenator'' was removed from the analysis, ''Ornitholestes'' was found to be a basal maniraptoran.

References

{{Taxonbar, from=Q609659 Coelurosauria Dinosaur genera Valanginian dinosaurs Barremian dinosaurs Aptian dinosaurs Dinosaurs of China Fossil taxa described in 2005 Taxa named by Xu Xing