Kaijiangosaurus

Kaijiangosaurus (meaning "Kiijiang lizard") is a genus of carnivorous tetanuran theropod dinosaur from the Middle Jurassic of China. In 1984 He Xinlu named and described the type species Kaijiangosaurus lini. The generic name refers to the River (jiang) Kai. The specific name honours the paleontologist Lin Wenqiu.[1]

Kaijiangosaurus
Temporal range: Middle Jurassic
Kaijiangosaurus SW
Speculative life restoration based on other theropods
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Clade: Tetanurae
Genus: Kaijiangosaurus
He, 1984
Type species
Kaijiangosaurus lini
He, 1984

Discovery

The holotype specimen, CCG 20020, was discovered in Sichuan, in a layer of the Xiashaximiao Formation dating from the Bathonian-Callovian. 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, 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.[1] 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 junior synonym of Gasosaurus, which was found in the same strata as Kaijiangosaurus, the Lower Shaximiao Formation section of the Dashanpu Formation, 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 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 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 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.[1]

Classification

He originally placed Kaijiangosaurus in the Megalosauridae.[1] Modern analysis suggests it is a basal member of the Tetanurae, or perhaps the Averostra.[2] 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.[3]

References

  1. ^ a b c d He Xinlu (1984). "The vertebrate fossils of Sichuan." Sichuan Scientific and Technological Publishing House, Chengdu. 40: 1-168
  2. ^ 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
  3. ^ Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Avetheropoda

Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.

Cerapoda

Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.

Gasosaurus

Gasosaurus (simplified Chinese: 气龙; traditional Chinese: 氣龍) () 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 σαῦρος/sauros ("lizard / generic reptile"). Only one species is currently recognised, G. constructus, from which the specific name honours the gasoline company that found the Dashanpu fossil quarry in Sichuan Province, China, now named as the Lower Shaximiao Formation.

Haya griva

Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.

Jeholosauridae

Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.

Jingshanosaurus

Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.

Melanorosauridae

The Melanorosauridae were a family of sauropodomorph dinosaurs which lived during the Late Triassic and Early Jurassic. The name Melanorosauridae was first coined by Friedrich von Huene in 1929. Huene assigned several families of dinosaurs to the infraorder "Prosauropoda": the Anchisauridae, the Plateosauridae, the Thecodontosauridae, and the Melanorosauridae. Since then, these families have undergone numerous revisions. Galton and Upchurch (2004) considered Camelotia, Lessemsaurus, and Melanorosaurus members of the family Melanorosauridae. A more recent study by Yates (2007) indicates that the melanorosaurids were instead early sauropods.

Neotheropoda

Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.

Orionides

Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.

Orodrominae

Orodrominae is a subfamily of parksosaurid dinosaurs from the Cretaceous of North America and Asia.

Powellvenator

Powellvenator is an extinct genus of coelophysoid theropod dinosaur that lived during the latter part of the Triassic Period in what is now northwestern Argentina. Fossils of the dinosaur were found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin. The type species, Powellvenator podocitus, was named by Martin Ezcurra in 2017.

Raeticodactylidae

Raeticodactylidae is a family of eudimorphodontoid eopterosaurian pterosaurs that lived in Switzerland during the Late Triassic. The family includes Caviramus, and the type genus Raeticodactylus, which are both known from the Kössen Formation, around 205 mya. Raeticodactylidae was first used in 2014 by Andres et al., as a group of all pterosaurs closer to Raeticodactylus than Eudimorphodon. The following phylogenetic analysis follows the topology of Andres et al. (2014).

Riojasauridae

Riojasauridae is a family of sauropod-like dinosaurs from the Upper Triassic. It is known primarily from the genera Riojasaurus and Eucnemesaurus. Sites containing Riojasauridae include the Lower Elliot Formation of Orange Free State, South Africa (where fossils of Eucnemesaurus have been found), and Ischigualasto, in La Rioja Province, Argentina ( where fossils of Riojasaurus have been recovered).

Unaysauridae

Unaysauridae is a family of basal sauropodomorphs from the Late Triassic of India and Brazil.

Xixiposaurus

Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.

Yueosaurus

Yueosaurus is an extinct genus of basal ornithopod dinosaur known from Zhejiang Province, China.

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