|Skeletal mount of Gigantspinosaurus in the Zigong Dinosaur Museum|
The first fossil was found in 1985 by Ouyang Hui at Pengtang near Jinquan and was reported upon in 1986 by Gao Ruiqi and colleagues, mistaking it for a specimen of Tuojiangosaurus. The type species, Gigantspinosaurus sichuanensis, was described and named by Ouyang in 1992 in an abstract of a lecture. The generic name is derived from Latin gigas or giganteus, "enormous", and spina, "spine", in reference to the gigantic shoulder spines. The specific name refers to Sichuan.
The name was generally considered a nomen nudum in the West, until in 2006 it was disclosed that the abstract contained a sufficient description. Despite its uncertain nomenclatural status, images of Gigantspinosaurus had appeared in several sources. Public awareness of this animal was increased in early 2006 when Tracy Ford, considering it a validly established taxon, published a short article on reconstructing it. Ford suggested that earlier reconstructions of Gigantspinosaurus attached the shoulder spines upside-down, and his new reconstruction shows the spine extending somewhat upwards, ending higher than the top of the animal's back. Susannah Maidment and Wei Guangbiao in 2006 concluded that G. sichuanensis was a valid taxon in their review of Late Jurassic Chinese stegosaurs, but did not redescribe it because at that time it was under study by Zigong Dinosaur Museum staff. In fact, a Chinese redescription by Peng Guangzhao and colleagues in 2005 would predate Maidment's publication.
The holotype, ZDM 0019, was found in layers of the Upper Shaximiao Formation of Zigong (Sichuan province), which date to the Oxfordian. It consists of a partial skeleton of a probably subadult individual missing the skull (though the lower jaws are present), hind feet, and the tail end. Apart from skeletal elements also plates, spines and scutes have been found. At the left shoulder an impression of the skin had been preserved. The specimen is part of the collection of the Zigong Dinosaur Museum and has as a mounted restored skeleton been on display since 1996. In 2005 Peng e.a. reported a second specimen, ZDM 0156, a pelvis found at Chenjia near Fuquan.
Gigantspinosaurus was described by Peng and colleagues as a "medium-sized stegosaur". It was estimated by Gregory S. Paul in 2010 to have been about 4.2 metres (14 ft) long and 700 kilograms (1,500 lb) in weight. Gigantspinosaurus has a distinctive appearance with relatively small dorsal plates and greatly enlarged shoulder spines, spinae parascapulares, twice the length of the shoulder blades on which they rested via large flat bases. The plates on the neck are small and triangular. The head must have been relatively large with thirty teeth in each lower jaw. The hips are very broad and the low neural spines of the four sacral vertebrae and the first tail vertebra have been fused into a single plate. The forelimbs are robust.
The skin impressions were described by Xing Lida and colleagues in 2008. They cover a surface of 414 square centimetres (64.2 sq in) and show rosettes with a central pentagonal or hexagonal scale surrounded by thirteen to fourteen ridged smaller square, pentagonal or hexagonal scales with a diameter of 5.7 to 9.2 millimetres (0.22 to 0.36 in).
A study by Maidment indicated that Gigantspinosaurus is the most basal known member of the Stegosauria. Peng and colleagues, however, placed it in the Huayangosaurinae. A 2018 redescription by Hao et al clarified aspects of the anatomy and found that it was an intermediate basal stegosaur, sharing basal traits with huayangosaurines as well as somewhat more advanced traits with other stegosaurs. Nevertheless, this analysis found that it was not the most basal stegosaur, as the huayangosaurids Chungkingosaurus and Huayangosaurus were considered more basal.
Ankylosaurinae is a subfamily of ankylosaurid dinosaurs, existing from the Early Cretaceous about 105 million years ago until the end of the Late Cretaceous, about 66 mya. Many genera are included in the clade, such as Ankylosaurus, Pinacosaurus, Euoplocephalus, and Saichania.Bienosaurus
Bienosaurus (meaning "Bien's lizard") is a genus of thyreophoran dinosaur from the Lower Jurassic (probably Sinemurian) Lower Lufeng Formation in Yunnan Province in China.Bissektipelta
Bissektipelta is a genus of herbivorous ankylosaurid dinosaur from the Upper Cretaceous of Uzbekistan. Bissektipelta is monospecific, containing only the species B. archibaldi.Chuanqilong
Chuanqilong is an extinct genus of ankylosaurid dinosaur from the Early Cretaceous of China. It is known from the type species, Chuanqilong chaoyangensis. It lived during the Aptian stage of early Cretaceous period (125 - 112 mya) and was about 4.5 meters long. Its weight is estimated at some 450 kg.Dongyangopelta
Dongyangopelta is an extinct genus of nodosaurid ankylosaurian dinosaur known from the "middle" Cretaceous Chaochuan Formation (Albian or Cenomanian stage) of Dongyang, Zhejiang Province, China. Dongyangopelta was first named by Rongjun Chen, Wenjie Zheng, Yoichi Azuma, Masateru Shibata, Tianliang Lou, Qiang Jin and Xingsheng Jin in 2013 and the type species is Dongyangopelta yangyanensis. It differs from Zhejiangosaurus, the second nodosaurid from southeast China, in the characters of presacral rod, ilium, and femur. Donyangopelta is distinguishable from Zhejiangosaurus only on the basis of the morphology of its pelvic shield.Invictarx
Invictarx is a genus of herbivorous nodosaurid dinosaur from New Mexico dating from the early Campanian epoch of the Late Cretaceous.Mongolostegus
Mongolostegus is a genus of stegosaur from the Early Cretaceous (Aptian-Albian) of Mongolia. The type and only species is M. exspectabilis, known from a single specimen previously under the nomen nudum Wuerhosaurus mongoliensis.Nodosaurinae
Nodosaurinae is a group of ankylosaurian dinosaurs named in 1919 by Othenio Abel.Nodosaurus
Nodosaurus (meaning "knobbed lizard") is a genus of herbivorous ankylosaurian dinosaur from the Late Cretaceous, the fossils of which are found in North America.Scelidosauridae
Scelidosauridae is a group of basal thyreophoran dinosaurs that lived during the Early Jurassic in what are now England, China, and North America with possible additional remains known from Portugal. The group was named in 1869 by Thomas Henry Huxley. Today it is generally considered paraphyletic, although Benton (2004) regards it as monophyletic.Silvisaurus
Silvisaurus, from the Latin silva "woodland" and Greek sauros "lizard", is a nodosaurid ankylosaur from the middle Cretaceous period.Stegosauria
Stegosauria is a group of herbivorous ornithischian dinosaurs that lived during the Jurassic and early Cretaceous periods. Stegosaurian fossils have been found mostly in the Northern Hemisphere, predominantly in what is now North America, Europe, Africa, South America and Asia Their geographical origins are unclear; the earliest unequivocal stegosaurian, Huayangosaurus taibaii, lived in China.
Stegosaurians were armored dinosaurs (thyreophorans). Originally, they did not differ much from more primitive members of that group, being small, low-slung, running animals protected by armored scutes. An early evolutionary innovation was the development of tail spikes, or "thagomizers", as defensive weapons. Later species, belonging to a subgroup called the Stegosauridae, became larger, and developed long hindlimbs that no longer allowed them to run. This increased the importance of active defence by the thagomizer, which could ward off even large predators because the tail was in a higher position, pointing horizontally to the rear from the broad pelvis. Stegosaurids had complex arrays of spikes and plates running along their backs, hips and tails. Their necks became longer and their small heads became narrow, able to selectively bite off the best parts of cycads with their beaks. When these plant types declined in diversity, so did the stegosaurians, which became extinct during the first half of the Cretaceous period.
The first stegosaurian finds in the early 19th century were fragmentary. Better fossil material, of the genus Dacentrurus, was discovered in 1874 in England. Soon after, in 1877, the first nearly-complete skeleton was discovered in the United States. Professor Othniel Charles Marsh that year classified such specimens in the new genus Stegosaurus, from which the group acquired its name, and which is still by far the most famous stegosaurian. During the latter half of the twentieth century, many important Chinese finds were made, representing about half of the presently known diversity of stegosaurians.Tatisaurus
Tatisaurus is a genus of ornithischian dinosaur from the Early Jurassic from the Lower Lufeng Formation in Yunnan Province in China. Little is known as the remains are fragmentary.Texasetes
Texasetes (meaning "Texas resident") is a genus of ankylosaurian dinosaurs from the late Lower Cretaceous of North America. This poorly known genus has been recovered from the Paw Paw Formation (late Albian) near Haslet, Tarrant County, Texas, which has also produced the nodosaurid ankylosaur Pawpawsaurus. Texasetes is estimated to have been 2.5–3 m (8–10 ft) in length. It was named by Coombs in 1995.Tianzhenosaurus
Tianzhenosaurus (Tianzhen + Greek sauros="lizard") is a genus of ankylosaurid dinosaurs discovered in Tianzhen County, at Kangdailiang near Zhaojiagou Village, in Shanxi Province, China, in the Late Cretaceous Huiquanpu Formation. Thus far, a virtually complete skull and postcranial skeleton have been assigned to the genus, which is monotypic (T. youngi Pang & Cheng, 1998).
This was a medium-sized ankylosaurian, the skull measuring 28 cm (11 in) in length, with a total body length around 4 m (13 ft).
Vickaryous et al. (2004) placed Tianzhenosaurus within the Ankylosauridae, nested as the sister group to Pinacosaurus. Some authors have suggested that Tianzhenosaurus is actually a junior synonym of Saichania chulsanensis.Tsagantegia
Tsagantegia (; meaning "of Tsagan-Teg"; Tumanova, 1993) is a genus of medium-sized ankylosaurid dinosaur from the Late Cretaceous of Mongolia, during the Cenomanian stage.
The holotype specimen (GI SPS N 700/17), a complete skull, was recovered from the Bayan Shireh Formation (Cenomanian-Santonian), at the Tsagan-Teg ("White Mountain") locality, Dzun-Bayan, in the southeastern Gobi Desert, Mongolia. The genus is monotypic, including only the type species, T. longicranialis.Wuerhosaurus
Wuerhosaurus is a genus of stegosaurid dinosaur from the Early Cretaceous Period of China and Mongolia. As such, it was one of the last genera of stegosaurians known to have existed, since most others lived in the late Jurassic.Yingshanosaurus
Yingshanosaurus (meaning "Yingshan or Golden Hills reptile") is a genus of stegosaurian dinosaur from the Late Jurassic, around 155 million years ago. It was a herbivore that lived in what is now China. The type species is Yingshanosaurus jichuanensis.Zigong Dinosaur Museum
The Zigong Dinosaur Museum (simplified Chinese: 自贡恐龙博物馆; traditional Chinese: 自貢恐龍博物館; pinyin: Zìgòng Kǒnglóng Bówùguǎn) is located near the city of Zigong, Sichuan, China, in the township of Dashanpu. The museum sits on top of a large concentration of a diverse dinosaur assemblage from the Dashanpu Formation. The museum claims the largest number of dinosaur fossils in the world and covers 25,000 square meters with a display area of 3,600 square meters. It attracts up to seven million visitors a year.In 1980s, vast quantities of dinosaur fossils were excavated in the Middle Jurassic Dashanpu Formation, 7 km north-east from downtown Zigong, including a dinosaur named after the township, Dashanpusaurus. Because of the unique and articulated (intact) bone remains, Zigong is important to paleontologists and dinosaur enthusiasts. The Zigong Dinosaur Museum was established in 1987, becoming the first museum based almost entirely on dinosaurs in Asia. Mounted specimens include Omeisaurus, Gigantspinosaurus, Yangchuanosaurus, Huayangosaurus and Xiaosaurus.