Dashanpu 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: 上·下沙溪庙地层; 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 found in the Dashanpu Formation, Dashanpusaurus dongi, was named in tribute of both Dashanpu and Dong Zhiming.

Paleobiota

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.

Sauropterygians

Genus	Species	Stratigraphic position	Material	Notes	Images
Pliosauridae	indet.	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A pliosaurid of an indeterminate genus.

Crocodyliformes

Genus	Species	Stratigraphic position	Material	Notes	Images
Teleosaurus	T. sp.	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A teleosaurid.	200px
Sunosuchus	S. shunanensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A goniopholid.	200px
Hsisosuchus	H. dashanpuensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A goniopholid.	200px

Pterosaurs

Genus	Species	Stratigraphic position	Material	Notes	Images
Angustinaripterus	A. longicephalus	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A rhamphorhynchoid.	200px

Dinosaurs

Ornithischians

Genus	Species	Stratigraphic position	Material	Notes	Images
Agilisaurus	A. louderbacki	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation			200px
Hexinlusaurus	H. multidens	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation			200px
Xiaosaurus	X. dashanpuensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation
Yandusaurus	Y. multidens	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation
	Y. hongheensis	Mamenchisaurus assemblage, Upper Shaximiao Formation
Huayangosaurus	H. taibaii	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A stegosaurian.
Gigantspinosaurus	G. sichuanensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A stegosaurian.
	G. sp.	Mamenchisaurus assemblage, Upper Shaximiao Formation		A stegosaurian.
Chungkingosaurus	C. jiangbeiensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A stegosaurian.
Tuojiangosaurus	T. multispinus	Mamenchisaurus assemblage, Upper Shaximiao Formation		A stegosaurian.
Chialingosaurus	C. kuani	Mamenchisaurus assemblage, Upper Shaximiao Formation		A stegosaurian.
Yingshanosaurus	Y. jichuanensis	Upper Shaximiao Formation	Nearly complete skeleton	A stegosaurian.
Gongbusaurus	G. shiyii	Mamenchisaurus assemblage, Upper Shaximiao Formation

Sauropods

Genus	Species	Stratigraphic position	Material	Notes	Images
Shunosaurus	S. lii	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation			200px
Protognathosaurus	P. oxyodon	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao formation
Omeisaurus	O. luoquanensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A mamenchisaurid.
	O. tianfuensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao formation		A mamenchisaurid.	200px
	O. junghsiensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A mamenchisaurid.
	O. changshouensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.
	O. maoi	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.
	O. fuxiensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.
Datousaurus	D. bashanensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A mamenchisaurid.	200px
Mamenchisaurus	M. constructus	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.
	M. hochuanensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.	200px
	M. fuxiensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.
	M. anyueensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.
	M. youngi	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.	200px
	M. jingyanensis	Mamenchisaurus assemblage, Upper Shaximiao Formation		A mamenchisaurid.	200px
Daanosaurus	D. zhangi	Mamenchisaurus assemblage, Upper Shaximiao Formation

Theropods

Genus	Species	Synonyms	Stratigraphic position	Material	Notes	Images
Chuandongocoelurus	C. primitivus		Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation
Leshansaurus	L. qianweiensis		Shunosaurus-Omeisaurus assemblage, Lower Shaximiao formation		A megalosaurid.
Szechuanosaurus	S. campi		Mamenchisaurus assemblage, Upper Shaximiao Formation		A megalosaurid. Remains from the Dashanpu Formation might represent an indeterminate theropod.	200px
Xuanhanosaurus	X. qilixiaensis		Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A megalosaurid.
Kaijiangosaurus	K. lini		Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A megalosaurid.
Gasosaurus	G. constructus		Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation			200px
Coeluroidea	gen. et sp. indet.		Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation
Sinocoelurus	S. fragilis		Mamenchisaurus assemblage, Upper Shaximiao Formation
Yangchuanosaurus	Y. shangyouensis	Y. magnus	Mamenchisaurus assemblage, Upper Shaximiao formation
	Y. hepingensis		Mamenchisaurus assemblage, Upper Shaximiao Formation		Probably represents a new genus.	200px
	Y. zigongensis	Szechuanosaurus zigongensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		ZDM 9011 (holotype), a partial postcranial skeleton; ZDM 9012, a left maxilla; ZDM 9013, two teeth and ZDM 9014, a right hind limb.	200px
Chienkosaurus	C. ceratosauroides		Mamenchisaurus assemblage, Upper Shaximiao Formation			200px

Turtles

Genus	Species	Stratigraphic position	Material	Notes	Images
Chengyuchelys	C. baenoides	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A chengyuchelyid.
	C. zigongensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A chengyuchelyid.
	C. dashanpuensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A chengyuchelyid.
	C. sp.	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A chengyuchelyid.
Sichuanchelys	S. chowi	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A chengyuchelyid.
Chengyuchelyidae	indet.	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		An indeterminate chengyuchelyid.
Plesiochelys	P. jingyanensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A plesiochelyid.	200px
Trionyx	T. sp.	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A trionychid.

Therapsids

Genus	Species	Stratigraphic position	Material	Notes	Images
Bienotheroides	B. zigongensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A tritylodontid.
Polistodon	P. chuannanensis	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		A tritylodontid.
Tritylodontidae	gen. et sp. indet.	Shunosaurus-Omeisaurus assemblage, Lower Shaximiao Formation		An indeterminate tritylodontid.

See also

• List of dinosaur-bearing rock formations

External links

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