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Upper Shaximiao Formation

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Upper Shaximiao Formation

Dashanpu Formation
Stratigraphic range: Mid Bathonian-Late Oxfordian
Type Geological formation
Sub-units Xiashaximiao Formation (Lower Shaximiao Formation), Shangshaximiao Formation (Upper Shaximiao Formation), Zhenchuchong Formation, Ziliujing Formation
Location
Region Sichuan
Country China
Type section
Named for Dashanpu

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.

Geology

The Dashanpu Formation includes four layers of rock: The upper and lower Shaximiao Formations (simplified Chinese: ·沙溪庙地层; traditional Chinese: 上·下沙溪廟地層; pinyin: shàng / xià Shāxīmiào dìcéng), although they are commonly referred to as one, simply being called "Shaximiao Formations". The upper Shaximiao Formation is also known as the Shangshaximiao Formation, and the lower Shaximiao Formation is also known as the Xiashaximiao Formation. The Shaximiao Formations are the most productive, despite being only two of four. The last two formations, the Zhenchuchong Formation and the Ziliujing Formation, are noticeably less productive and remain relatively unexplored.

Dinosaur finds

The Dashanpu Formation has produced mainly sauropods, but has also held numerous other dinosaur types, such as theropods and stegosaurians amongst others. In total, over 8,000 pieces of bone have been unearthed from the area – amounting to nearly 40 tonnes. The site was unknown until the early 1970s, when a Chinese gas company unearthed Gasosaurus in 1972. It would be the first of the many dinosaurs to be uncovered from the area. Most specimens found are held at the Zigong Dinosaur Museum which has been placed on the area during the mid-1980s.

Despite being a frequented "dinosaur-quarry" at present, the Dashanpu Formation was once a lush forest, evidence of which has been found alongside dinosaur remains in the form of fossilised wood. Paleontologists speculate that the area also had a lake that was fed by a large river. Dinosaur remains would have been swept toward the lake over millions of years, thus accounting for the hundreds of specimens found. Paleontologists have dated parts of the formation at about 168 to 161 million years old, between the Bathonian to Callovian stages of the Mid Jurassic.

Zhiming's research

The paleontologist who has made the largest contribution to the formation and its excavation is Dong Zhiming. He first examined the formation in 1975, after bone fragments were found embedded in rock from the area. The site was being demolished to make way for both a natural gas field facility and a vehicle park when Zhiming first saw the area. Amongst the extensive clearings, Zhiming found numerous bone fragments which were exposed.

However, the specimens were being damaged due to bulldozers in the area and there would be little chance of closing the area as the state had invested millions of yuan in the site already. It was not until 1985 that the government finally agreed to close the construction on the site, and by then Zhiming and his team had already excavated over 100 dinosaurs from the area, including several rare sauropod skulls. A dinosaur was found in the Dashanpu Formation which was named in tribute of both Dashanpu and Dong Zhiming; Dashanpusaurus dongi.

Paleobiota of the Dashanpu Formation

In addition to dinosaur finds, many other prehistoric finds have been uncovered from the Dashanpu Formation. Amongst these finds are fishes, amphibians, turtles, marine reptiles such as crocodiles and also pterosaurs. Bienotheroides, a Tritylodont Synapsid has been found there, as well as Sinobrachyops, a Labyrinthodont.

Labyrinthodonts

Genus Species Location Member Material Description

Sinobrachyops

Synapsids

Genus Species Location Member Material Description

Bienotheroides

Pterosaurs

Genus Species Location Member Material Description

Angustinaripterus[1]

A. longicephalus[1]

Lower Shaximiao Formation.[1]

Ornithischians

Indeterminate Stegosaurid remains have been found in the Upper Shaximiao Formation of Sichuan.[2]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Genus Species Location Member Material Description Images

Agilisaurus[3]

A. louderbacki[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Nearly complete skeleton with skull."[4]

A. multidens[3]

"Nearly complete skeleton with skull."[4]

Chialingosaurus[2]

C. kuani[2]

Sichuan

Upper Shaximiao Formation.[2]

"Partial postcranial skeleton, subadult."[5]

Chungkingosaurus[2]

C. jiangbeiensis[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"Incomplete skeleton with skull, [three] fragmentary postcrania, adult."[5]

Dianchungosaurus

D. lufengensis

"Fragmentary skull."[6]

Gongbusaurus[2]

G. shiyii[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"Teeth."[7]

Later determined to be indeterminate ornithischian remains.[2]

Gigantspinosaurus[8]

G. sichuanensis

Sichuan

Upper Shaximiao Formation.

Partial postcranial skeleton, subadult.

Hexinlusaurus

Huayangosaurus[3]

H. taibaii[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Complete skeleton with complete skull, [five] fragmentary postcrania, adult."[5]

Sanpasaurus[9]

S. yaoi[9]

Sichuan[9]

Ziliujing Formation[9]

Later determined to be indeterminate ornithopod remains.[9]

Tuojiangosaurus[2]

T. multispinus[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"[Two] partial skeletons."[10]

Xiaosaurus[3]

X. dashanpensis[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Teeth and isolated postcranial material."[7]

Yandusaurus[3]

Y. hongheensis[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Nearly complete skeleton with skull."[11]

Sauropodomorphs

Indeterminate prosauropod remains formerly attributed to the anchisauridae have been recovered from Zhenzhunchong outcrops in Sichuan.[9]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Genus Species Location Member Material Description Images

Abrosaurus[9]

A. dongpoi[9]

Sichuan[3]

Lower Shaximiao Formation[3]

"Skull."[12]

Dashanpusaurus

Datousaurus[3]

D. bashanensis[3]

Sichuan[3]

"[Two] partial skeletons without skulls, [and possible] jaws."[13]

Lower Shaximiao Formation[3]

Gongxianosaurus[9]

G. shibeiensis.[9]

Sichuan[9]

Ziliujing Formation[9]

"Postcranial skeleton."[13]

cf. Lufengosaurus[9]

cf. L. huenei[9]

Sichuan[9]

Zhenzhunchong Formation[9]

cf. L magnus[9]

Sichuan[9]

Zhenzhunchong Formation[9]

Actually referrable to cf. L. huenei.[9]

Mamenchisaurus[2]

M. constructus[2]

Sichuan[2]

Upper Shaximiao Formation[2]

M. fuxiensis

"Maxilla, teeth, dentary, basioccipital, dorsal vertebrae, pubis, [and] ischium."[14]

M. hochuanensis.[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"[Four] partial skeletons without skulls."[14]

M. jingyanensis.[2]

Sichuan[2]

Upper Shaximiao Formation[2]

M. youngi.[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"Skull and skeleton."[14]

Omeisaurus[2]

O. changshouensis[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"Partial skeleton."[15]

Later determined to be indeterminate sauropod remains.[2]

O. fuxiensis[2]

Sichuan[2]

Upper Shaximiao Formation[2]

Later determined to be indeterminate sauropod remains.[2]

O. jiaoi[16]

Sichuan

Lower Shaximiao Formation

Nearly complete skeleton

O. junghsiensis[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Several partial skeletons."[14]

O. luoquanensis[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Partial skeleton."[15]

Later determined to be indeterminate sauropod remains.[3]

O. tianfuensis[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Skeleton with partial skull."[14]

Mamenchisaurus fuxiensis[3] may be O. tianfuensis?

Protognathosaurus[3]

P. oxyodon[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Dentary."[15]

Later determined to be indeterminate sauropod remains.[3]

Sanpasaurus[9]

S. yaoi[9]

Sichuan[9]

Ziliujing Formation[9]

"Isolated postcranial elements."[15]

Later determined to be indeterminate sauropod remains.[9]

Shunosaurus[3]

S. lii[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"As many as [twenty] skeletons with [five] skulls."[14]

Zizhongosaurus[9]

Z. chuanchengensis[9]

Sichuan[9]

Ziliujing Formation[9]

Later determined to be indeterminate sauropod remains.[9]

Theropods

Indeterminate Theropod remains have been recovered from the Ziliujing Formation in Sichuan.[2][3][9][9]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Genus Species Location Member Material Description Images

Chuandongocoelurus[3]

C. primitivus[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Vertebrae, [a possible] scapula, pelvis, femur, tibia, fibula, [and] partial pes."[17]

Gasosaurus[3]

G. constructus[3]

Sichuan[3]

Lower Shaximiao Formation[3]

"Postcranial skeleton."[18]

Kaijiangosaurus[3]

K. lini[3]

Sichuan[3]

Lower Shaximiao Formation[3]

Vertebrae.[19]

Leshansaurus[20]

L. qianweiensis

Sichuan

Upper Shaximiao Formation

One fairly complete skeleton and an isolated femur.[21]

Sinraptor[2]

S. hepingensis[2]

Sichuan[2]

Upper Shaximiao Formation[2]

Probably represents a new genus.[22]

Szechuanosaurus[3]

S. campi[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"Isolated teeth."[17]

Later determined to be an indeterminate theropod.[2][22]

S. "yandonensis"

Sichuan[2]

Upper Shaximiao Formation[2]

CV 00214, a partial postcranial skeleton lacking the skull.[22]

A nomen nudum. It was assigned to Szechuanosaurus campi, and later it was reassigned to Yangchuanosaurus shangyouensis.[22]

S. zigongensis[3]

Sichuan[3]

Lower Shaximiao Formation[3]

Fragmentary postcranial remains and two partial skeletons.[23]

Reclassified as Yangchuanosaurus zigongensis.[22]

Xuanhanosaurus[3]

X. qilixaensis[3]

Sichuan[3]

Lower Shaximiao Formation[3]

Vertebrae and a forelimb.[23]

Yangchuanosaurus[2]

Y. magnus[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"Skull, vertebrae, pelvis, [and a] femur."[24]

Junior synonym of Y. shangyouensis.[22]

Y. shangyouensis[2]

Sichuan[2]

Upper Shaximiao Formation[2]

"Skeleton lacking forelimbs, pes, and distal caudal series."[24]

Y. zigongensis[22]

Sichuan[22]

Lower Shaximiao Formation[22]

ZDM 9011 (holotype), a partial postcranial skeleton; ZDM 9012, a left maxilla; ZDM 9013, two teeth and ZDM 9014, a right hind limb.[22]

See also

References

Earth sciences portal
Paleontology portal
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Dinosaurs portal

External links

  • Dong Zhiming account of Dashanpu Formation
  • "Xiashaximiao Formation" at DinoData
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