''Kaijiangosaurus'' (meaning "Kaijiang lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of carnivorous

tetanuran Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most theropod dinosaurs, including megalosauroids, allosauroids, tyrannosauroids, ornithomimosaurs, compsognathids and maniraptorans (including birds). Tetanurans ar ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

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

from the Middle

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

of China. In 1984 He Xinlu named and described 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 ...

''Kaijiangosaurus lini''. The generic name refers to the River (''jiang'') Kai. The specific name honours the paleontologist Lin Wenqiu.

Discovery

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 ...

specimen, CCG 20020, was discovered before 1984 in

Sichuan Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of the ...

, in a layer of the

Xiashaximiao Formation The Shaximiao Formation () is a Middle to Late Jurassic aged geological formation in Sichuan, China, most notable for the wealth of dinosaurs fossils that have been excavated from its strata. The Shaximiao Formation is exposed in and around th ...

dating from the

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Str ...

Callovian In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the ...

. The specimen consists of a fragmentary skeleton lacking the skull. The holotype proper contains the intercentrum of the atlas and the third to ninth neck vertebrae. Other elements have been designated as a

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). O ...

, including fragmentary remains of the skull, nine teeth, elements of the pectoral girdle, a forelimb, and a hindlimb. Another paratype is the thighbone of a probably smaller individual.He Xinlu (1984). "The vertebrate fossils of Sichuan." Sichuan Scientific and Technological Publishing House, Chengdu. 40: 1-168 Holtz ''et al.'' (2004) mentioned much more complete specimens, but they are undescribed. There have been doubts about the validity of ''Kaijiangosaurus''. It has been suggested that it should be regarded as a synonym of ''

Gasosaurus ''Gasosaurus'' () is a genus of tetanuran theropod that lived approximately 171.6 to 161.2 million years ago during the middle of the Jurassic Period. The name "''Gasosaurus''" is derived from the English "''gasoline''" and the Greek () ( ...

'', which was found in the same strata as ''Kaijiangosaurus'', the

Lower Shaximiao Formation The Shaximiao Formation () is a Middle Jurassic, Middle to Late Jurassic aged geological formation in Sichuan, China, most notable for the wealth of dinosaurs fossils that have been excavated from its strata. The Shaximiao Formation is exposed in ...

, or of '' Xuanhanosaurus''.

Description

''Kaijiangosaurus'' had a length of about five metres. He mentioned some diagnostic traits. The jugal is straight-edged at the front, deeper at the rear. The teeth are of the megalosaurid type. Their leading edge has only few serrations, near the tip. The cervicals are short, wide and narrow in the middle. The front cervicals have spines with a concave trailing edge. These neck vertebrae are about as wide as they are long; their spines are low and wide. The centra of the rear cervical are concave at their back; their spines are long and narrow. The dorsals are platycoelous and have smooth sides lacking pleurocoels. The front tail vertebrae are also platycoelous, with a flat front and concave rear; the rear caudals are amphicoelous. The

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...

vertebrae have flat undersides without a midline groove. The scapula is rather straight with only a relative constriction at the lower end and a light expansion at the upper end. The

coracoid A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...

is oval and has a thick ridge at the upper outer side. With the humerus, the deltopectoral crest is triangular; the shaft has an oval cross-section. The

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

is short and expanded at both ends. The three claws of the hand are strongly curved. Both ends of the thighbone are expanded; the neck is somewhat directed to the rear. The lesser trochanter is low, with a triangular profile. The middle metatarsals are not fused, nor is the third metatarsal constricted at the top.

Classification

He originally placed ''Kaijiangosaurus'' in the

Megalosauridae Megalosauridae is a monophyletic family of carnivorous theropod dinosaurs within the group Megalosauroidea. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dinosaurs. They were a relatively ...

. Modern analysis suggests it is a basal member of the

Tetanurae Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most theropod dinosaurs, including megalosauroids, allosauroids, tyrannosauroids, ornithomimosaurs, compsognathids and maniraptorans (including birds). Tetanurans ar ...

, or perhaps the

Averostra Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs, namely Ceratosauria and Tetanurae, and represent the only group of post-Early Jurassic theropods. Both survived into the Cretaceous period. When the Cretaceous–Pa ...

.Carrano, M.T.; Benson, R.B.J.; & Sampson, S.D., 2012, "The phylogeny of Tetanurae (Dinosauria: Theropoda)", Journal of Systematic Palaeontology 10(2): 211–300 Due to the fragmentary nature of the remains, it is uncertain what type of tetanuran theropod it is, though it may be a primitive

carnosaur Carnosauria is an extinct large group of predatory dinosaurs that lived during the Jurassic and Cretaceous periods. Starting from the 1990s, scientists have discovered some very large carnosaurs in the carcharodontosaurid family, such as ''Gig ...

.Holtz, Thomas R. Jr. (2012) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'
Winter 2011 Appendix.
/ref>

References

{{Taxonbar, from=Q871868 Middle Jurassic dinosaurs of Asia Prehistoric tetanurans Fossil taxa described in 1984 Paleontology in Sichuan