Gongxianosaurus

Gongxianosaurus
Temporal occurrence
Lower Jurassic ( Toarcium )
182.7 to 174.1 million years
Locations
Sichuan , China ( Dashanpu Formation )
Systematics
Dinosaur (dinosauria) Lizard dinosaur (Saurischia) Sauropodomorpha Sauropods (Sauropoda) Gongxianosaurus
Scientific name
Gongxianosaurus
He et al., 1998
Art
Gongxianosaurus shibeiensis He et al., 1998

Gongxianosaurus is a genus of very original sauropod dinosaurs from the lower Jurassic of China . The only species is Gongxianosaurus shibeiensis . Gongxianosaurus is one of the most fully transmitted original sauropods: the skeleton is largely known, only the hand skeleton and most of the skull are missing. The genus was first described in a brief report in 1998 , but extensive scientific work is still pending.

The name Gongxianosaurus shibeiensis refers to the site near the village of Shibei in Gong district (珙 县; Pinyin : Gǒng Xiàn).

description

Gongxianosaurus is estimated to be 14 meters long. Like all sauropods, this genus moved four-legged, as shown by the elongated front legs, which made up 70 to 75% of the length of the hind legs. The phalanges (phalanges) were typically short and robust, the phalangeal formula of the foot (the number of phalanges , counted from the innermost to the outermost ray) was 2-3-4-5-1. All but the extreme toe ended in claws. Weight-saving lateral cavities in the vertebrae ( pleurocoele ), as demonstrated by later sauropods, were missing, making the vertebrae quite massive. The sacrum consisted of three sacral vertebrae fused together. The chevron bones were not bifurcated.

Typical of all sauropods was the low level of ossification of the limbs - the tendency to replace bone mass in the joints with cartilage . Gongxianosaurus is the only sauropod of which ossified lower (distal) tarsal bones have survived. This very original feature could suggest that the ancestors of Gongxianosaurus split off from the main line of development of the sauropods very early. It is unclear whether this characteristic was actually missing in other early sauropods or whether it is simply not known as a result of the fragmentary preservation.

Systematics

Cladogram , simplified after Apaldetti and colleagues (2011)
Sauropoda  Melanorosaurus     Camelotia     Blikanasaurus  unnamed  Lessemsaurus     Antetonitrus  unnamed  Gongxianosaurus  Gravisauria  Vulcanodon     Tazoudasaurus     Isanosaurus     Eusauropoda
Systematic position of Gongxianosaurus

Since an exact description is still pending, Gongxianosaurus has so far only been considered in a few cladistic analyzes. A recent analysis by Cecilia Apaldetti and colleagues (2011) suggests that Gongxianosaurus was more basal (primitive) than Vulcanodon , Tazoudasaurus, and Isanosaurus , but more derived (more advanced) than the early sauropods Antetonitrus , Lessemsaurus , Blikanasaurus , Camelotia, and Melanorosaurus .

Find history

Gongxianosaurus comes from a locality near the village of Shibei in the Chinese province of Sichuan . The location includes purple-colored pelites of the Ziliujing Formation (Dongyueshan Member), a layer member of the Dashanpu Formation , and can be dated to the Toarcian . This means that the fossils are younger than those of the " prosauropod " Lufengosaurus , but older than those of the very well known early sauropod Shunosaurus .

The fossils were discovered in May 1997 during a geological survey. The excavation work, which began that same month, uncovered numerous fossils over an area of ​​around 200 square meters, including four fragmentary to complete Gongxianosaurus skeletons, but also remains of theropods . In 1998 the first description followed in the form of a short report by a research group around He Xinlu , who named and described the new genus of sauropods Gongxianosaurus . The excavation work had not yet been completed at this point, and more extensive investigations were announced. In 2000, a second brief description by Luo Yaonan and Wang Changsheng appeared. This publication, held in the style of a first description, presented Gongxianosaurus as a new sauropod, the first description by He and colleagues, published two years earlier, is not mentioned. The content also largely coincides with the first description by He and his colleagues.

Luo and Wang report that various bones found in Shibei may not belong to Gongxianosaurus shibeiensis , but belong to a second Gongxianosaurus species.

Individual evidence

1. ↑ ^{a b} Gongxianosaurus . In: The Paleobiology Database. Retrieved August 15, 2014 . 
2. ↑ ^{a b c d e f} Luo Yaonan, Wang Changsheng: A New Sauropod, Gongxianosaurus, from the Lower Jurassic of Sichuan, China. In: Acta Geologica Sinica. English edition. Vol. 74, No. 2, 2000, ISSN  1000-9515 , pp. 132-136, doi : 10.1111 / j.1755-6724.2000.tb00440.x .
3. ↑ ^{a b c} He Xinlu, Wang Changsheng, Liu Shangzhong, Zhou Fengyun, Liu Tuqiang, Cai Kaiji, Dai Bing: A new species of sauropod from the Early Jurassic of Gongxian Co., Sichuan. In: Acta Geologica Sichuan. Vol. 18, No. 1, 1998, ISSN  1006-0995 , pp. 2-7, (In Chinese language and writing).
4. ^ Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 259-324, here p. 298.
5. ↑ Jeffrey Wilson: Overview of Sauropod Phylogeny and Evolution. In: Kristina Curry Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. 2005, ISBN 0-520-24623-3 , pp. 26-27.
6. ↑ ^{a b} Cecilia Apaldetti, Ricardo N. Martinez, Oscar A. Alcober, Diego Pol: A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina. In: PLoS ONE . Vol. 6, No. 1, 2011, doi : 10.1371 / journal.pone.0026964 .
7. ↑ Donald F. Glut : Gongxianosaurus. In: Donald F. Glut: Dinosaurs. The Encyclopedia. 3rd supplement. McFarland, Jefferson NC et al. 2003, ISBN 0-7864-1166-X , pp. 349-350.