Shunosaurus

Shunosaurus, meaning "shu lizard", is a genus of sauropod dinosaur from Early Jurassic (Oxfordian) beds in Sichuan Province in China, approximately 159±2 million years ago[1]. The name derives from "Shu", an ancient name for the Sichuan province.

Shunosaurus
Temporal range: Early Jurassic, 159 Ma
Shunosaurus - Finnish Museum of Natural History
Mount in the Finnish Museum of Natural History
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Eusauropoda
Genus: Shunosaurus
Dong et al., 1983
Type species
Shunosaurus lii
Dong et al., 1983
Other species
  • Shunosaurus jiangyiensis
    Fu & Zhang, 2004

Description

Shunosaurus was first estimated to be 11 metres (36 ft) long; later and more complete finds indicated a somewhat smaller size. In 2010 Gregory S. Paul estimated the length at 9.5 metres (31 ft), the weight at 3 metric tons (3.3 short tons).[2] Shunosaurus was very short-necked for a sauropod, being only "surpassed" in this respect by Brachytrachelopan.[3] The skulls found are mostly compressed or disarticulated and the interpretation of the head form has varied from broad, short and deep[4] to extremely narrow and pointed.[5] The upper and lower jaws were strongly curved upwards, allowing them to function as a pair of garden shears. The teeth were fairly robust but elongated with a crown length of up to 8 centimetres (3.1 in). They show a unique combination of a cylindrical body ending in a spatulate tip. In 1989 it was disclosed that the tail ended in a club,[6] equipped on its top with two successive spikes formed by 5 centimetres (2.0 in)-long cone-shaped osteoderms probably used to fend off enemies.

Shunosaurus life restoration

Life restoration

Shunosaurus李氏蜀龙头骨

Skull

Discovery and species

Shunosaurus-Tianjin Natural History Museum
Skeletal cast mount, Tianjin Natural History Museum

The first fossil of Shunosaurus was discovered in 1977 by a group of students, practising paleontological excavation at a road bank. The type species, Shunosaurus lii, was described and named by Dong Zhiming, Zhou Shiwu and Zhang Yihong in 1983. The generic name derives from "Shu", an ancient name for Sichuan. The specific name honours hydrologist Li Bing, the governor of Sichuan in the third century BC.[7]

The holotype, IVPP V.9065, was collected from the Lower Xiashaximiao Formation near Dashanpu, Zigong. It consists of a partial skeleton. Later about twenty more major specimens were discovered, including several complete or near-complete skeletons, skulls and juveniles,[8] making Shunosaurus one of the best anatomically known sauropods, with 94% of all skeletal elements identified. Shunosaurus skeletons are on display at the Zigong Dinosaur Museum in Zigong, Sichuan Province, and the Tianjin Natural History Museum.

A second species, S. ziliujingensis, a name mentioned in the Zigong museum guide to indicate a smaller and older form, has never been formally described, and thus remains a nomen nudum.

Classification

Shunosaurus Scale
Size comparison

Shunosaurus was originally classified as a member of the Cetiosaurinae; in 1992 Dong assigned it to Shunosaurinae within the Cetiosauridae.[9]

Cladistic analyses have rendered conflicting results. In 1995 Paul Upchurch published a study in which Shunosaurus belonged to the Euhelopodidae together with other Jurassic Chinese sauropods.[10] However, an analysis by Jeffrey Wilson in 2002 indicated it had a very basal position within the Eusauropoda.[11] Shunosaurus is perhaps related to Rhoetosaurus from Queensland in Australia.

The cladogram below shows a possible phylogenetic position:[12]

Sauropoda

Melanorosaurus

Camelotia

Blikanasaurus

 

Lessemsaurus

Antetonitrus

Gongxianosaurus

Gravisauria

Vulcanodon

Tazoudasaurus

Isanosaurus

Eusauropoda

Shunosaurus

Patagosaurus

Omeisaurus

Mamenchisaurus

Barapasaurus

unnamed

Cetiosaurus

Neosauropoda

Paleobiology

Zigong Dinosaur Museum Shunosaurus tail club
Tail-club

Its neck length indicates that Shunosaurus was a low browser. The form of its jaws is well-adapted to processing large amounts of coarse plant material.[13]

Shunosaurus accounts for 90% of the fossils found in the Dashanpu fauna, showing it was a dominant and/ or common member of its habitat and environment. It shared the local Middle Jurassic landscape with other sauropods, Datousaurus, Omeisaurus and Protognathosaurus, the possible ornithopod Xiaosaurus, and the early stegosaur Huayangosaurus, as well as the carnivorous theropod Gasosaurus.

References

  1. ^ Wang, Jun; Ye, Yong; Pei, Rui; Tian, Yamin; Feng, Chongqin; Zheng, Daran; Chang, Su-Chin (2018-09-01). "Age of Jurassic basal sauropods in Sichuan, China: A reappraisal of basal sauropod evolution". GSA Bulletin. 130 (9–10): 1493–1500. doi:10.1130/B31910.1. ISSN 0016-7606.
  2. ^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 173
  3. ^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 175
  4. ^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 174
  5. ^ Zheng , Zhong (1996). Cranial Anatomy of Shunosaurus and Camarasaurus (Dinosauria: Sauropoda) and the phylogeny of the Sauropoda. Dissertation Texas Tech University. pp. 208
  6. ^ Dong Z., Peng G., Huang D. 1989. [The discovery of the bony tail club of sauropods]. Vertebrata PalAsiatica 27: 219–224
  7. ^ Dong, Z., Zhou, S. & Zhang, Y. 1983. [Dinosaurs from the Jurassic of Sichuan]. Palaeontologica Sinica, New Series C 162(23): 1-136
  8. ^ Zhang Y., Yang D. & Peng G., 1984, "[New materials of Shunosaurus from the Middle Jurassic of Dashanpu, Zigong, Sichuan]", Journal of Chengdu College of Geology 2: 1–12
  9. ^ Dong Zhiming (1992). Dinosaurian Faunas of China. China Ocean Press, Beijing. ISBN 3-540-52084-8.
  10. ^ P. Upchurch. 1995. "The evolutionary history of sauropod dinosaurs". Philosophical Transactions of the Royal Society of London B 349: 365-390
  11. ^ J. A. Wilson. 2002. "Sauropod dinosaur phylogeny: critique and cladistic analysis". Zoological Journal of the Linnean Society 136: 217-276
  12. ^ J.A. Wilson, 2002, "Sauropod dinosaur phylogeny: critique and cladistic analysis", Zoological Journal of the Linnean Society 136: 217-276
  13. ^ Chatterjee, S. & Zheng, Z. 2002. "Cranial anatomy of Shunosaurus, a basal sauropod dinosaur from the Middle Jurassic of China". Zoological Journal of the Linnean Society 136(1): 145–169
  • Dong Zhiming (1988). Dinosaurs from China. China Ocean Press, Beijing & British Museum (Natural History). ISBN 0-565-01073-5.
Austrosaurus

Austrosaurus (meaning "Southern lizard") was an extinct genus of sauropod dinosaur from the Allaru Formation and Winton Formation, from the early Cretaceous (110-105 million years ago) of Central-Western Queensland in Australia.

Barapasaurus

Barapasaurus ( bə-RAH-pə-SAWR-əs) 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.

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.

Chinshakiangosaurus

Chinshakiangosaurus (JIN-shah-jiahng-uh-SOR-us, meaning "Chinshakiang lizard") is a genus of dinosaur and probably one of the most basal sauropods known. The only species, Chinshakiangosaurus chunghoensis, is known from a fragmentary skeleton found in Lower Jurassic rocks in China. Chinshakiangosaurus is one of the few basal sauropods with preserved skull bones and therefore important for the understanding of the early evolution of this group. It shows that early sauropods may have possessed fleshy cheeks.

Club (anatomy)

In zoology, a club is a bony mass at the end of the tail of some dinosaurs and of some mammals, most notably the ankylosaurids and the glyptodonts, as well as meiolaniid turtles. It is thought that this was a form of defensive armour or weapon that was used to defend against predators, much in the same way as a thagomizer, possessed by stegosaurids, though at least in glyptodonts it is hypothesized it was used in fighting for mating rights. Among dinosaurs, the club was present mainly in ankylosaurids, although the sauropod Shunosaurus also possessed a tail club. The tail club is most often depicted on Ankylosaurus, especially in encounters with larger predators such as Tyrannosaurus. Victoria Arbour has established that ankylosaurid tails could generate enough force to break bone during impacts.

Dashanpu Formation

The Dashanpu Formation is a Mid to Late Jurassic rock formation in China, most notable for the wealth of dinosaurs that have been excavated from the area. The Dashanpu Formation sits in and around the small township of Dashanpu (simplified Chinese: 大山铺镇; traditional Chinese: 大山鋪鎮; pinyin: Dàshānpū zhèn), situated seven kilometres north-east from Sichuan's third largest city, Zigong, in the Da'an District.

Datousaurus

Datousaurus, meaning "Big-head Lizard" (from the Chinese da tou "Big Head" and Greek sauros/σαυρος "lizard") was a dinosaur from the Middle Jurassic. It was a sauropod collected from the Lower Shaximiao Formation in Dashanpu, Zigong Sichuan province, China. It shared the local Middle Jurassic landscape with other sauropods such as Shunosaurus, Omeisaurus, Protognathosaurus, the ornithopod Xiaosaurus, the early stegosaur Huayangosaurus as well as the carnivorous Gasosaurus.

Dong Zhiming

Dong Zhiming (Chinese: 董枝明, Pinyin: Dǒng Zhimíng; born January 1937), of the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing, is a Chinese vertebrate paleontologist. He began working at the IVPP in 1962, studying under Yang Zhongjian, who was director at the time. He has described fossil remains of many dinosaurs, including sauropods such as Shunosaurus, Datousaurus and Omeisaurus, as well as Archaeoceratops. He investigated and described the Dashanpu Formations; an important contribution to science since they are composed of Middle Jurassic beds which do not commonly yield fossils.

Euhelopodidae

Euhelopodidae is a family of sauropod dinosaurs which includes the genus Euhelopus. All known euhelopodids lived in what is now East Asia. The family name was first proposed by American paleontologist Alfred Sherwood Romer in 1956. The four genera Chiayusaurus, Omeisaurus, Tienshanosaurus, and Euhelopus were the original proposed euhelopodines (subfamily Euhelopodinae). Other genera such as Mamenchisaurus and Shunosaurus were formerly placed within this family, but these are now regarded as more basal sauropods.

Michael D'Emic (2012) formulated the first phylogenetic definition of Euhelopodidae, defining it as the clade containing "neosauropods more closely related to Euhelopus zdanskyi than to Neuquensaurus australis". Below is a cladogram presenting the cladistic hypothesis of Euhelopodidae proposed by D'Emic.

Eusauropoda

Eusauropoda (meaning "true sauropods") 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.Eusauropoda are herbivorous, quadrupedal, and have long necks. They have been found in South America, Europe, North America, Asia, Australia, and Africa. The temporal range of Eusauropoda ranges from the early Jurassic to the Latest Cretaceous periods. The most basal forms of eusauropods are not well known and because the cranial material for the Vulcanodon is not available, and the distribution of some of these shared derived traits that distinguish Eusauropoda is still completely clear.

Gravisauria

Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.

Hexinlusaurus

Hexinlusaurus is a genus of basal ornithischian dinosaur from the Middle Jurassic of China. The holotype (ZDM T6001, Zigong Dinosaur Museum, Dashanpu, People's Republic of China), consists of an almost complete, articulated skull and some postcranial material, collected from a terrestrial sandstone within the Lower Shaximiao Formation (?Bajocian) at the famous dinosaur-bearing quarries at Dashanpu. A paratype (ZDM T6002) consists of a partial skull and postcranial remains. Previously, it had been described as a species of Yandusaurus, Y. multidens (He and Cai, 1983), but was reclassified as a new taxon by Paul M. Barrett, Richard J. Butler and Fabien Knoll in 2005, who diagnosed this anatomically conservative species as follows: "A small ornithischian dinosaur distinguished from all other basal ornithischians by a single autapomorphy, the presence of a marked concavity that extends over the lateral surface of the postorbital." The etymology of the genus name honors Professor He Xin-Lu (from the Chengdu University of Technology) who originally named the specimen as Y. multidens + the Greek sauros (=lizard). Hexinlusaurus was a small, fleet-footed herbivore.

Other dinosaurs known from Dashanpu include the sauropod Shunosaurus, the theropod Gasosaurus, and the stegosaur Huayangosaurus.

Before being officially named Hexinlusaurus, this genus was briefly known under the informal name "Proyandusaurus". This name originally appeared in an abstract attributed to Fabien Knoll, which was apparently published without his consent.[1][2]

Huayangosaurus

Huayangosaurus is a genus of stegosaurian dinosaur from the Middle Jurassic of China. The name derives from "Huayang" (華陽), an alternate name for Sichuan (the province where it was discovered), and "saurus", meaning "lizard". It lived during the Bathonian to Callovian stages, around 165 million years ago, some 20 million years before its famous relative, Stegosaurus appeared in North America. At only 4.5 metres long, it was also much smaller than its famous cousin. Found in the Lower Shaximiao Formation, Huayangosaurus shared the local Middle Jurassic landscape with the sauropods Shunosaurus, Datousaurus, Omeisaurus and Protognathosaurus, the ornithopod Xiaosaurus and the carnivorous Gasosaurus. It was found in Huayang in China.

Nebulasaurus

Nebulasaurus is an extinct genus of basal eusauropod dinosaur known from the early Middle Jurassic Zhanghe Formation (Aalenian or Bajocian stage) of Yunnan Province, China. It is known only from the holotype braincase LDRC-v.d.1. A phylogenetic analysis found Nebulasaurus to be a sister taxon to Spinophorosaurus from the Middle Jurassic of Africa. This discovery is significant paleontologically because it represents a clade of basal eusauropods previously unknown from Asia.

Neosauropoda

Neosauropoda is a clade within Dinosauria, coined in 1986 by Argentine paleontologist José Bonaparte and currently described as Saltasaurus loricatus, Diplodocus longus, and all animals directly descended from their most recent common ancestor. The group is composed of two subgroups: Diplodocoidea and Macronaria. Arising in the early Jurassic and persisting until the Cretaceous-Paleogene extinction event, Neosauropoda contains the majority of sauropod genera, including genera such as Apatosaurus, Brachiosaurus, and Diplodocus. It also includes giants such as Argentinosaurus, Patagotitan and Sauroposeidon, and its members remain the largest land animals ever to have lived.When Bonaparte first coined the term Neosauropoda in 1986, he described the clade as comprising “end-Jurassic” sauropods. While Neosauropoda does appear to have originated at the end of the Jurassic period, it also includes members through the end of the Cretaceous. Neosauropoda is currently delineated by specific shared, derived characteristics rather than the time period in which its members lived. The group was further refined by Upchurch, Sereno, and Wilson, who have identified thirteen synapomorphies shared among neosauropods. As Neosauropoda is a subgroup of Sauropoda, all members also display basic sauropod traits such as large size, long necks, and columnar legs.

Omeisaurus

Omeisaurus (meaning "Omei lizard") is a genus of sauropod dinosaur from the Middle Jurassic Period (Bathonian-Callovian stage) of what is now China. Its name comes from Mount Emei, where it was discovered in the lower Shaximiao Formation of Sichuan Province.

Like other sauropods, Omeisaurus was herbivorous and large. It measured 20.2 metres (66 ft) long, and weighed 9.8 tonnes.

Rhoetosaurus

Rhoetosaurus (meaning "Rhoetos lizard"), named after Rhoetus, a titan in Greek Mythology, is a genus of sauropod dinosaur from the Jurassic Hutton Sandstone of what is now eastern Australia. Rhoetosaurus is estimated to have been about 15 metres (49 ft) long, weighing about 9 tonnes (8.9 long tons; 9.9 short tons). Subsequent authors have sometimes misspelled the name: Rhaetosaurus (de Lapparent & Laverat, 1955); Rheteosaurus (Yadagiri, Prasad & Satsangi, 1979).

Spinophorosaurus

Spinophorosaurus is a genus of sauropod dinosaur that lived in what is now Niger during the Middle Jurassic period. The first two specimens were excavated in the 2000s by German and Spanish teams under difficult conditions. The skeletons were brought to Europe and digitally replicated, making Spinophorosaurus the first sauropod to have its skeleton 3D printed, and were to be returned to Niger in the future. Together, the two specimens represented most of the skeleton of the genus, and one of the most completely known basal sauropods of its time and place. The first skeleton was made the holotype specimen of the new genus and species Spinophorosaurus nigerensis in 2009; the generic name ("spine-bearing lizard") refers to its spiked osteoderms, and the specific name refers to where it was found. A juvenile sauropod from the same area was later assigned to the genus.

The subadult holotype specimen is estimated to have been around 13 m (43 ft) in length, whereas the paratype was about 14 m (46 ft) long. The shoulder height reached by these individuals was estimated at around 4 m (13 ft), and the weight at about 7 metric tons (7.7 short tons). The braincase was short, deep, and broad, and the neuroanatomy was in some ways intermediate between that of basal sauropodomorphs and the more derived neosauropods. The teeth were spatulate (spoon shaped) and had large spaced denticles at the top of the crown, an ancestral feature in sauropods. The neck of Spinophorosaurus is one of the most completely known among sauropods, containing 13 vertebrae. The dorsal vertebrae had multiple small, air-filled internal chambers, a feature typical of later, more derived sauropods. The tail was powered by strong musculature and had a rear section that was rather rigid due to long and overlapping chevron bones. Osteoderms bearing spikes appear to have been placed on the tail tip in two pairs); a similar feature is seen in the related Shunosaurus.

Spinophorosaurus has been classified as either a very basal sauropod, or inside Eusauropoda, a more derived group. The anatomy, age, and location of specimens indicate that important developments in sauropod evolution may have occurred in North Africa, possibly controlled by climatic zones and plant biogeography. Features of the vestibular apparatus suggest that vision and coordinated eye, head, and neck movements were important in Spinophorosaurus. Due to the completeness of Spinophorosaurus, 3D models have been made of the skeleton, and used to test its range of motion. One study suggests it may have been a high browser, and another examined possible mating postures. The spikes on the tail may have been used for defence. Sutures between the neural arches with the centra of the vertebrae were more complex in the front part of the trunk of Spinophorosaurus, since stresses were probably greatest in that region. Spinophorosaurus is known from the Irhazer Shale, a geological formation thought to be Middle Jurassic in age. It was formed by deposits from rivers and lakes in a great river-valley system.

Yuanmousaurus

Yuanmousaurus ("Yuanmou lizard") was a sauropod dinosaur from the Middle Jurassic period of China. It is known from incomplete remains, recovered in 2000 from the Zhanghe Formation in Yuanmou County in Yunnan Province. Yuanmousaurus was a relatively large sauropod and may have reached about 17 meters (56 ft) in length. It was a basal member of the Sauropoda, but its exact systematic position is unclear. A recent study placed Yuanmousaurus within the family Mamenchisauridae. The only and type species was Yuanmousaurus jiangyiensis.

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