Description and feeding
Like all sauropods, it was a large, quadrupedal herbivore with long neck and tail. The body length of the only specimen is estimated at 12 to 13 meters. [2] The remains consists of the dentary (the tooth bearing bone of the mandible) including teeth as well as several parts of the postcranium. By now, only the dentary and the teeth were studied extensively; the remaining skeleton still awaits a proper description. [1]
The dentary was curved in dorsal view, so that the mandibles formed a U-shaped, broad snout. This feature is typical for sauropods – in Prosauropods, on the contrary, the dentary was straight, forming a V-shaped, tapered snout. Paul Upchurch and colleagues (2007) suppose that this differences can give hints about feeding habits: The prosauropods with their tapered snouts possibly where selective feeders, who ate only certain plant parts, whereas sauropods with their broad snouts where bulk feeders, adapted to consume large amounts of foliage. [1]
The tooth size increased towards the tip of the snout, like in sauropods. Another derived, sauropod like feature was a bony plate that lined the tooth row laterally and became thicker towards the tip of the snout. This plate may have hindered the teeth to be displaced while defoliating plants. [1]
The dentary was deep. However, as in prosauropods, it became lower towards the tip of the snout, while in sauropods the dentary became deeper, forming a very deep symphysis. [1] [3] In lateral view, the dentary shows a prominent ridge running diagonally across the bone. Apart from Chinshakiangosaurus, this feature is only known from prosauropods, where it is interpreted as the insertion point of a fleshy cheek. [1] [4] Such cheeks would have prohibited food falling out of the mouth and may be a hint that the food underwent some degree of oral processing before it was swallowed. If Chinshakiangosaurus indeed was a basal sauropod, this would be the first evidence of cheeks in this group. In all other sauropods known from congruous remains this feature had been reduced already. [1]
On each side of the mandible there were 19 teeth – more than in all known sauropods, but fewer than in the prosauropod Plateosaurus . The teeth were lanceolate and furnished with coarse denticles; therewith they resemble those of prosauropods more than those of sauropods. However, the lingual side of the teeth already was slightly concave, possibly an initial state towards the strongly concave, spoon shaped teeth that were typical for sauropods. [1]
Discovery
The fossils were found in 1970 by Zhao Xijin and colleagues in Yongren County [7] in central Yunnan. They come from the Fengjiahe Formation, which is made up of mudstones, siltstones and sandstones that were deposited fluvolacustrine (inside rivers and lakes). Fossils of invertebrates like ostracodes and bivalves were used to determine these sediments as Upper Jurassic in age. A more precise dating could not be made. [1]
The holotype specimen (IVPP V14474) consists of a left dentary, one cervical and several dorsal and caudal vertebrae, both scapulae, some pelvic bones and the hind limbs. C. H. Ye mentioned this specimen in 1975 under the name Chinshakiangosaurus chunghoensis (after the Yangtze River and the village Zhonghe). However, because he did not provide a description of the fossils, the name was a nomen nudum (nacked name) until Dong Zhiming published a short description in 1992. [1] [2] Since then, the authorship is correctly cited as "Chinshakiangosaurus chunghoensis Ye vide Dong, 1992". [1]
After Dong's description, this genus, though potentially valid, remained unnoticed by most paleontologists. It was mentioned by Upchurch and colleagues (2004), who classified it as a nomen dubium inside Sauropoda. [6] In 2007, Upchurch and colleagues published a comprehensive description of the dentary and the teeth and declared Chinshakiangosaurus as a valid taxon. [1]
Barapasaurus is a genus of basal sauropod dinosaur from Early Jurassic rocks of India. The only species is B. tagorei. Barapasaurus comes from the lower part of the Kota Formation, that dates back to the Sinemurian and Pliensbachian stages of the early Jurassic. It is therefore one of the earliest known sauropods. Barapasaurus is known from approximately 300 bones from at least six individuals, so that the skeleton is almost completely known except for the anterior cervical vertebrae and the skull. This makes Barapasaurus one of the most completely known sauropods from the early Jurassic.
Diplodocids, or members of the family Diplodocidae, are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including Diplodocus and Supersaurus, some of which may have reached lengths of up to 42 metres (138 ft).
Vulcanodon is an extinct genus of sauropod dinosaur from the Early Jurassic of southern Africa. The only known species is V. karibaensis. Discovered in 1969 in Zimbabwe, it was regarded as the earliest-known sauropod for decades, and is still one of the most primitive sauropods that has been discovered. As a quadrupedal, ground-dwelling herbivore, Vulcanodon already showed the typical sauropod body plan with column-like legs and a long neck and tail. It was smaller than most other sauropods, measuring approximately eleven metres (36 ft) in length. Vulcanodon is known from a fragmentary skeleton including much of the pelvic girdle, hindlimbs, forearms, and tail, but lacking the trunk and neck vertebrae as well as the skull.
Lufengosaurus is a genus of massospondylid dinosaur which lived during the Early Jurassic period in what is now southwestern China.
Asiatosaurus is an extinct genus of herbivorous sauropod dinosaur which lived during the Early Cretaceous in Mongolia and China. The type species is known only from teeth, making it difficult to rely on information until more specimens are found to expand our knowledge, and another species is known, also based on scant remains; both are now classified as nomina dubia..
Cardiodon was a herbivorous genus of sauropod dinosaur, based on a tooth from the late Bathonian-age Middle Jurassic Forest Marble Formation of Wiltshire, England. Historically, it is very obscure and usually referred to Cetiosaurus, but recent analyses suggest that it is a distinct genus, and possibly related to Turiasaurus. Cardiodon was the first sauropod genus named.
Zigongosaurus is a genus of sauropod dinosaur from the Middle Jurassic-Late Jurassic-age Shaximiao Formation of Zigong, Sichuan, China. Because of incomplete knowledge of Jurassic Chinese sauropods, it has been hard to interpret, with some sources assigning it to Omeisaurus, some to Mamenchisaurus, and some to its own genus.
Trimucrodon is a genus of ornithischian dinosaur from the Late Jurassic of Portugal. Three isolated teeth found at the Porto Dinheiro locality in the Lisboa District of Portugal were given the name in 1973 by Richard A. Thulborn, derived from the Latin words for "three" and a dagger point, tri- and mucro, and the Ancient Greek word ὀδούς for "tooth". The only species in the taxon is Trimucrodon cuneatus, taken from the wedge shape of the teeth. Though the unit the specimens came from was originally unnamed, it was referred to the Alcobaça, and then Lourinhã Formations, specifically the late Kimmeridgian Amoreira–Porto Novo Member. The type specimen, uncovered between 1962 and 1967 by German zoologist and paleontologist Georg Krusat, is distinguished by prominent denticles at the front and rear ends of the crown, and comes from an individual under 2 m (6.6 ft) long. It is currently kept in the collections of the Museu Geológico do Instituto Geológico e Mineiro in Lisbon, Portugal, formerly having been kept in the collections of the Free University of Berlin.
Neosodon was a genus of sauropod dinosaur from the Late Tithonian-age Upper Jurassic Sables et Gres a Trigonia gibbosa of Départment du Pas-de-Calais, France. It has never been formally given a species name, but is often seen as N. praecursor, which actually comes from a different animal. Often in the past, it had been assigned to the wastebasket taxon Pelorosaurus, but restudy has suggested that it could be related to Turiasaurus, a roughly-contemporaneous giant Spanish sauropod. It is only known from six teeth.
Oplosaurus was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is known from a single tooth usually referred to the contemporaneous "wastebasket taxon" Pelorosaurus, although there is no solid evidence for this.
Hudiesaurus is a herbivorous sauropod genus of dinosaur from China. Its fossil remains were found in 1993 by a Chinese-Japanese expedition near Qiketai in Shanshan, Xinjiang province. The genus contains a single species, Hudiesaurus sinojapanorum, was named and described by Dong Zhiming in 1997. The generic name is derived from Mandarin hudie, meaning "butterfly," and refers to a flat butterfly-shaped process on the front base of the vertebral spine. The specific name refers to the members of the Sino-Japan Silk Road Dinosaur Expedition but can also be read as "central part" in Chinese, a pun on the Japanese Chunichi Shinbun press group, which financed the research.
Gongbusaurus is a genus of ornithischian, perhaps ornithopod, dinosaur that lived between about 160 and 157 million years ago, in the Late Jurassic period. A small herbivore, it is very poorly known. Two species have been assigned to it, but as the original name is based on teeth, there is no concrete evidence to connect the two species. Its fossils have been found in China.
Gongxianosaurus is a genus of basal sauropod dinosaur from the early Jurassic Period. The only species is Gongxianosaurus shibeiensis. Based on four fragmentary to complete specimens found in China, it is one of the most completely known early sauropods. The skeleton is known in large part, missing both the hand and the majority of the skull. Gongxianosaurus was firstly named and described in a short note published in 1998; however, a comprehensive description has yet to be published. Gongxianosaurus shibeiensis was named for the place it was found, near the village Shibei in Gong County.
Microhadrosaurus is a genus of hadrosaurid dinosaur from the Campanian or Maastrichtian-age Upper Cretaceous Yuanpu Formation of Guangdong, China. Although its name identifies it as a small hadrosaur, it is based on juvenile remains, and the size of the adult hadrosaur is unknown.
Lourinhasaurus was an herbivorous sauropod dinosaur genus dating from Late Jurassic strata of Estremadura, Portugal.
Camarasauridae is a family of sauropod dinosaurs. Among sauropods, camarasaurids are small to medium-sized, with relatively short necks. They are visually identifiable by a short skull with large nares, and broad, spatulate teeth filling a thick jaw. Based on cervical vertebrae and cervical rib biomechanics, camarasaurids most likely moved their necks in a vertical, rather than horizontal, sweeping motion, in contrast to most diplodocids.
Dongbeititan is a genus of sauropod dinosaur from the Early Cretaceous-age Yixian Formation of Beipiao, Liaoning, China. It is based on holotype DNHM D2867, a partial postcranial skeleton including bones from the limbs, shoulder and pelvic girdles, and vertebrae, which was described in 2007. Its describers suggested it was as a basal titanosauriform, not as derived as Gobititan or Jiutaisaurus, but more derived than Euhelopus, Fusuisaurus, and Huanghetitan. The type species is D. dongi, and it is the first named sauropod from the Yixian Formation, which is part of the well-known Jehol Group. The genus name refers to the region Dongbei and to Greek titan, "giant". The specific name honours the Chinese paleontologist Dong Zhiming. Like other sauropods, Dongbeititan would have been a large quadrupedal herbivore.
Uberabatitan is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous of Brazil. It is known from bones including neck, back, and tail vertebrae, pelvic bones, and limb bones. These fossils were found in the uppermost portion of the Maastrichtian-age Marília Formation of the Bauru Group, in Uberaba, Minas Gerais. The type species, described by Salgado and Carvalho in 2008, is U. ribeiroi. To date, it is the most recent titanosaur from Bauru Group rocks; other titanosaurs from the Bauru Group, including Baurutitan and Trigonosaurus, come from lower levels. Like other sauropods, Uberabatitan would have been a large quadrupedal herbivore.
Duriavenator is a genus of theropod dinosaur that lived in what is now England during the Middle Jurassic, about 168 million years ago. In 1882, upper and lower jaw bones of a dinosaur were collected near Sherborne in Dorset, and Richard Owen considered the fossils to belong to the species Megalosaurus bucklandii, the first named non-bird dinosaur. By 1964, the specimen was recognised as belonging to a different species, and in 1974 it was described as a new species of Megalosaurus, M. hesperis; the specific name means 'the West' or 'western'. Later researchers questioned whether the species belonged to Megalosaurus, in which many fragmentary theropods from around the world had historically been placed. After examining the taxonomic issues surrounding Megalosaurus, Roger B. J. Benson moved M. hesperis to its own genus in 2008, Duriavenator; this name means "Dorset hunter".
Eusauropoda is a derived clade of sauropod dinosaurs. Eusauropods represent the node-based group that includes all descendant sauropods starting with the basal eusauropods of Shunosaurus, and possibly Barapasaurus, and Amygdalodon, but excluding Vulcanodon and Rhoetosaurus. The Eusauropoda was coined in 1995 by Paul Upchurch to create a monophyletic new taxonomic group that would include all sauropods, except for the vulcanodontids.
