Shishugou Formation

Shishugou Formation
Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Approximate paleocoordinates	42°30′N 100°30′E / 42.5°N 100.5°E / 42.5; 100.5
Region	Xinjiang
Country	China
Extent	Northern Junggar Basin
Shishugou Formation (Dzungaria)

The Shishugou Formation (

Its strata date back to the

The Wucaiwan Member, once considered a separate, underlying formation,[4] is now considered the lowest unit of the Shishugou Formation.

Lithology

At the Wuwaican locality, the formation is approximately 380 m thick, the lower 30 metres of the formation predominantly consist of conglomerate, with the majority of the formation consisting of red coloured mudstone with frequent channel/sheet sandstone lenses and occasional tuffaceous deposits.^[3] It is laterally equivalent to the Qigu Formation in the southern half of the Junggar Basin.

Shishugou Formation dinosaur traps

The Shishugou Formation dinosaur traps also known as death pits or death traps are pit structures found within the formation that are noted for their fossil content.

Paleontology

These 'traps' or 'bonebeds' are unusual in that they consist of vertically stacked skeletons of numerous non-avian theropods in 1–2 metres (3.3–6.6 ft) deep pits. The pits are filled with a mix of alluvial and volcanic mudstone and sandstone and appear to have been created by the trampling and wallowing of large dinosaurs. Small theropods and vertebrates then became mired in these pits, dying and being forced deeper by the activities of the large dinosaurs and the struggles of later victims. The high quality of preservation suggests a rapid burying of the carcasses. Some scavenging of the bodies took place leading to a dispersal of body parts. Smaller vertebrates were prone to getting stuck in these mudholes, and the small ceratosaur,

At the time the area was covered by marshland, adjoined a small mountain range peppered with volcanoes, and was inhabited by dinosaurs, small crocodilians and amphibians. Currently it is a sparsely settled region of dry washes, arid badlands and dunes along the

When the site was first excavated, new species of turtles, crocodilians, pterosaurs, and early mammals were revealed. Many of these species showed the rudiments of characteristics that would later become their hallmarks. One of the first fossil skeletons exposed proved to be that of an unknown

Genus	Species	Stratigraphic position	Abundance	Notes	Images
" Eugongbusaurus "	"E. wucaiwanensis"	Upper		An unspecified basal neornithischian), previously classified as Gongbusaurus wucaiwanensis.[2] It is estimated at around 1.3 to 1.5 meters (4.3 to 4.9 ft) long.
Hualianceratops	H. wucaiwanensis	Upper		An early ceratopsian.[7]
Jiangjunosaurus	J. junggarensis	Upper		A stegosaurid reaching around 6 meters (20 feet) in length and weighed 2.5 metric tons.[8] It had three distinguishing traits: the crowns of the teeth are symmetrical and in side view wider than tall; the spine of the axis, the second neck vertebra, has a rectangular profile in side view, instead of a triangular one; and the rear neck vertebrae have large vein openings in their sides.
Yinlong	Y. downsi	Upper		A very basal and most primitive ceratopsian (possibly a chaoyangsaurid). It was bipedal and had a total length of about 1.2 meters (3.9 feet) from nose to tail, and a weight of about 15 kilograms (33 pounds).[9]

Pterosaurs

Genus	Species	Stratigraphic position	Abundance	Notes	Images
Kryptodrakon	K. progenitor	Upper		A basal pterodactyloid with an estimated wingspan of 1.47 meters (4.8 feet).
Sericipterus	S. wucaiwanensis	Upper		A rhamphorhynchid with a wingspan that has been estimated at least 1.73 meters.[10]

Sauropods

Sauropods of the Shishugou Formation
Genus	Species	Stratigraphic position	Material	Notes	Images
Bellusaurus	B. sui	base of Upper		A short-necked sauropod only known from juvenile specimens which measured about 4.8 meters (16 feet) long.[4]
Fushanosaurus[11]	F. qitaiensis	Upper	Complete right femur	A titanosauriform estimated to have been approximately 98 feet long, which would then make it one of the longest known dinosaurs.
Klamelisaurus	K. gobiensis	Wucaiwan member		A eusauropod measuring 15 meters and weighing 5 metric tons.
Mamenchisaurus	M. sinocanadorum	Upper	"Partial skull and skeleton."[12]	A mamenchisaurid with a remarkably long neck which made up half the total body length.[2] It is one of the largest dinosaurs known, measuring 35 meters (115 feet) in length with an 18-meter-long (59 feet) neck.
Tienshanosaurus	T. chitaiensis	Upper	"Partial postcranial skeleton."[13]	A mamenchisaurid known from very few remains.[2]

Theropods

Undescribed

Genus	Species	Stratigraphic position	Abundance	Notes	Images
Aorun	A. zhaoi	Wucaiwan member		A basal alvarezsaur that was at best 1 meter (3.3 feet) long and weighed 2 kilograms (4.4 pounds) at most.[3]
Guanlong	G. wucaii	Upper		A tyrannosaurs, about 3 meters (9.8 feet).[14] It has a large distinctive crest on its head, a feature seen in many primitive tyrannosaurs
Haplocheirus	H. sollers	Upper		An alvarezsaur that was the largest known definite member of the superfamily, at around 2 meters long. It had an enlarged thumb claw like other alvarezsaurs, but also retained two other functional fingers, unlike more derived alvarezsaurs, where only the thumb was significantly large and clawed.[15]
Limusaurus	L. inextricabilis	Upper		A toothless, omnivorous Eastern Asia, including China.[16] Limusaurus had a small slender body measuring about 1.7 meters in length.
Monolophosaurus	M. jiangi	Wucaiwan member		A tetanuran named for the single crest on top of its skull. It is estimated to have a length at 5.5 meters (16.4 feet), the weight at 475 kilograms.
Shishugounykus	S. inexpectus	Upper		A little-known early alvarezsaur.
Sinraptor	S. dongi	Upper		A metriacanthosaurine metriacanthosaur theropod standing nearly 3 meters (9.8 feet) tall and measuring roughly 7.6 meters (25 feet) in length.
Zuolong	Z. salleei	Upper		A basal gray wolf. The specimen known is probably from a juvenile individual and is quite complete.[17]

Crocodylomorphs

After an overview of crocodylomorphs of the Junggar Basin, Wings et al. identified the following species from the Shishugou Formation.^[18]

Genus	Species	Stratigraphic position	Abundance	Notes	Images
Crocodyliformes indet.		Upper	A single fully articulated skeleton	Found on the same slab that also preserved the holotype and an associated specimen of Limusaurus inextricabilis[16][5]
Junggarsuchus	J. sloani	Upper
Sunosuchus	S. junggarensis	Upper		Goniopholidid
Nominosuchus	N. matutinus	Upper		Shartegosuchid

Mammaliamorphs

See also

• Jurassic Asia
• Jurassic paleontological sites
• List of dinosaur-bearing rock formations

References