Gongxianosaurus

Gongxianosaurus is a genus of basal sauropod dinosaur from the early Jurassic Period (Toarcian stage[1]). The only species is Gongxianosaurus shibeiensis. Based on four fragmentary to complete specimens found in China (Sichuan Province), 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.[2] Gongxianosaurus was firstly named and described in a short note published in 1998;[3] however, a comprehensive description has yet to be published.[4] Gongxianosaurus shibeiensis was named for the place it was found, near the village Shibei in Gong County (珙县; Pinyin: Gǒng Xiàn).[2]

Gongxianosaurus
Temporal range: Early Jurassic 183–174 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Genus: Gongxianosaurus
Species:
G. shibeiensis
Binomial name
Gongxianosaurus shibeiensis
He et al., 1998

Description

Gongxianosaurus may have reached 14 metres (46 ft) in length.[2] Like other sauropods, it moved quadrupedally (on four legs), as indicated by the elongated fore limbs that reached 70 to 75% of hind limb length.[2] The pedal phalanges were short and robust, as typical for sauropods. The pedal phalangeal formula, counting the number of phalanges for each digit starting from the innermost, was 2-3-4-5-1. All but the outermost digit ended in claws.[2] Unlike in other sauropods, pleurocoels (deep lateral excavations of the vertebrae) were absent;[2] thus, the vertebrae would have been quite massive. The sacrum was made of three fused sacral vertebrae, fewer than in later sauropods.[2][5] The chevrons were unbifurcated.[2]

An important characteristic of sauropod limbs is their reduced ossification – the tendency to replace bone by cartilage. Gongxianosaurus is the only known sauropod with ossified distal tarsals. Thus, either Gongxianosaurus was one of the basalmost sauropods, or ossified distal tarsals were present in other early sauropods but are simply not preserved due to the fragmentation of the specimens.[5]

Classification

Sauropoda

Melanorosaurus

Camelotia

Blikanasaurus

unnamed

Lessemsaurus

Antetonitrus

Gongxianosaurus

Gravisauria

Vulcanodon

Tazoudasaurus

Isanosaurus

Eusauropoda

Basal Sauropod phylogeny simplified after Apaldetti et al. (2011).[6]

Because the fossils are not fully described yet, available character information that can be used in cladistic analyses is limited. Thus, only few cladistical analyses have incorporated Gongxianosaurus. A recent analysis by Apaldetti et al. (2011) suggests that Gongxianosaurus was more basal than Vulcanodon, Tazoudasaurus and Isanosaurus, but more derived than the early sauropods Antetonitrus, Lessemsaurus, Blikanasaurus, Camelotia and Melanorosaurus.[6]

Discovery

Gongxianosaurus fossils were found near the village of Shibei (Sichuan province) in purple mudstones pertaining to the Ziliujing Formation (Dongyueshan Member), a subunit of the Dashanpu Formation.[3] These rocks are considered to be Toarcian in age (182.7 to 174.1 mya).[1] Thus, Gongxianosaurus is geologically younger than the "prosauropod" Lufengosaurus but older than the basal sauropod Shunosaurus.[3]

The fossils were found in May 1997 during a geological exploration. Excavation started in the same month and led to the recovery of a wealth of fossils in an area of approximately 200 square meters. While most fossils pertain to a new sauropod genus, remains of theropods have also been found.[3] The sauropod material includes four fragmentary to complete individuals similar in size, together encompassing most of the skeleton, though hand and skull bones were not found except a premaxilla and teeth. In 1998, the sauropod material was briefly described as a new genus and species, Gongxianosaurus shibeiensis, in a preliminary note by palaeontologists led by He Xinlu.[3] A more detailed description was announced, noting that excavation was still in progress while the paper was published.[3] In 2000, a second short description was published by Luo Yaonan and Wang Changsheng, also presenting Gongxianosaurus as a new sauropod and without mentioning the first description that was published two years before.[2][7] Also, much of the information published by Luo and Wang was already published by He and colleagues.[7]

Luo and Wang suggest that several bones may do not pertain to the type species Gongxianosaurus shibeiensis but to a second species of Gongxianosaurus.[2]

References

  1. ^ a b "Gongxianosaurus". The Paleobiology Database. Retrieved 24 December 2012.
  2. ^ a b c d e f g h i j Yaonan, Luo; Wang Changsheng (2000). "A New Sauropod, Gongxianosaurus, from the Lower Jurassic of Sichuan, China". Acta Geologica Sinica - English Edition. 74 (2): 132–136. doi:10.1111/j.1755-6724.2000.tb00440.x. ISSN 1755-6724.
  3. ^ a b c d e f He, Xinlu; Wang Changsheng; Liu Shangzhong; Zhou Fengyun; Liu Tuqiang; Cai Kaiji; Dai Bing (1998). "A new species of sauropod from the Early Jurassic of Gongxian Co., Sichuan". Acta Geologica Sichuan. 18 (1): 1–7.
  4. ^ Upchurch, Paul; Paul Barrett; Peter Dodson (2004). "Sauropoda". In Weishampel, Dodson, Osmólska (eds.). The Dinosauria (2nd ed.). University of California Press. p. 298. ISBN 978-0-520-24209-8.CS1 maint: Uses editors parameter (link)
  5. ^ a b Wilson, Jeffrey (2005). "Overview of Sauropod Phylogeny and Evolution". In Rogers and Wilson (eds.). The Sauropods: Evolution and Paleobiology. University of California Press. pp. 26–28. ISBN 978-0-520-24623-2.CS1 maint: Uses editors parameter (link)
  6. ^ a b Apaldetti, Cecilia; Ricardo N. Martinez; Oscar A. Alcober; Diego Pol (9 November 2011). "A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina". PLoS ONE. 6 (11): 16. doi:10.1371/journal.pone.0026964. PMC 3212523. PMID 22096511.
  7. ^ a b Glut, Donald F. (2003). "Gongxianosaurus". Dinosaurs: The Encyclopedia. 3rd Supplement. Jefferson, North Carolina: McFarland & Company, Inc. pp. 349–350. ISBN 978-0-7864-1166-5.
Antetonitrus

Antetonitrus is a genus of sauropod dinosaur found in Early Jurassic rocks in South Africa. The only species is Antetonitrus ingenipes. As one of the oldest known sauropods, it is crucial for the understanding of the origin and early evolution of this group. It was a quadrupedal herbivore, like all of its later relatives, but shows primitive adaptations to use the forelimbs for grasping, instead of purely for weight support.

Blikanasaurus

Blikanasaurus cromptoni is a genus of sauropodomorph dinosaur from the late Triassic of South Africa. The generic name Blikanasaurus is derived from Greek, meaning “lizard from Blikana.” The species name cromptoni is taken from the surname of A.W. “Fuzz” Crompton, an American paleontologist who led numerous field expeditions in Elliot Formation outcrop localities in South Africa. Blikanasaurus is only known from partial hindlimb bones that were recovered from the lower Elliot Formation (LEF) in the Eastern Cape.

Daxiatitan

Daxiatitan is a genus of titanosaur dinosaur from the Lower Cretaceous of Lanzhou Basin, Gansu Province, northwestern China. It is known from fossils including several neck vertebrae, a shoulder blade, and a thigh bone.It was a very large dinosaur, estimated at 23–30 meters (75–98 feet). Like both Euhelopus and Huanghetitan, it had an enormously long neck.

Diplodocinae

Diplodocinae is an extinct subfamily of diplodocid sauropods that existed from the Late Jurassic to Early Cretaceous of North America, Europe and South America, about 161.2 to 136.4 million years ago. Genera within the subfamily include Tornieria, Supersaurus, Leinkupal, Galeamopus, Diplodocus, Kaatedocus and Barosaurus.Cladogram of the Diplodocidae after Tschopp, Mateus, and Benson (2015).

Ferganasaurus

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Flagellicaudata

Flagellicaudata is a clade of Dinosauria. It belongs to Sauropoda and includes two families, the Dicraeosauridae and the Diplodocidae.

Gravisauria

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

Huangshanlong

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Jiutaisaurus

Jiutaisaurus is a genus of sauropod dinosaur from the Quantou Formation of China. Jiutaisaurus was a sauropod which lived during the Cretaceous. The type species, Jiutaisaurus xidiensis, was described by Wu et al. in 2006, and is based on eighteen vertebrae.

Kaijutitan

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Ledumahadi

Ledumahadi (meaning "a giant thunderclap" in Sesotho language) is a genus of lessemsaurid sauropodomorph dinosaur from the Early Jurassic Elliot Formation in Free State Province, South Africa. The type and only species is L. mafube, known from a singular incomplete postcranial specimen. A quadruped, it was one of the first giant sauropodomorphs, reaching a weight of around 12 tonnes (26,000 lb), despite not having evolved columnar limbs like its later huge relatives.

Oceanotitan

Oceanotitan is a genus of titanosauriform sauropod known from the Upper Jurassic Praia da Amoreira-Porto Novo Formation of Portugal. It contains one species, Oceanotitan dantasi.The holotype consists of the scapula, almost all of the pelvis, a complete leg sans the toes, and nine caudals.

Pilmatueia

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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. The name derives from "Shu", an ancient name for the Sichuan province.

Tambatitanis

Tambatitanis is an extinct genus of titanosauriform dinosaur from the Early Cretaceous (probably early Albian) of Japan. It is known from a single type species, Tambatitanis amicitiae. It was probably around 14 meters long and its mass was estimated at some 4 tonnes. It was a basal titanosauriform and possibly belonged to the Euhelopodidae.

Tengrisaurus

Tengrisaurus (meaning "Tengri lizard") is a genus of lithostrotian sauropod, from the Early Cretaceous (Barremian-Aptian), of the Murtoi Formation, Russia. It was described in 2017 by Averianov & Skutschas. The type species is T. starkovi.

Vulcanodontidae

The Early Jurassic sauropod dinosaurs Zizhongosaurus, Barapasaurus, Tazoudasaurus, and Vulcanodon may form a natural group of basal sauropods called the Vulcanodontidae. Basal vulcanodonts include some of the earliest known examples of sauropods. The family-level name Vulcanodontidae was erected by M.R. Cooper in 1984. In 1995 Hunt et al. published the opinion that the family is synonymous with the Barapasauridae. One of the key morphological features specific to the family is an unusually narrow sacrum.

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