Xinminbao Group

Xinminbao Group Stratigraphic range: Early Cretaceous
Type	Geological formation
Location
Region	Asia

The Xinminbao Group is a group of geological formations in north central China. They occur across a large depression between the Altai mountains of Mongolia to the north and the Qilian mountains of the Qinghai Plateau to the south, in the Gonpoquan and Suanjingze basins, and also in the neighbouring Jiuquan Basin.

Both of these areas are inland basins consisting of fluvial (river), lacustrine (lake), and intermontane (between mountains) alluvial fan (floodplain) sediments that were deposited during the Early Cretaceous, probably during the Aptian or possibly late Barremian stage, when the climate was semi-arid and subtropical.

The Group has been visited by many expeditions including the Silk Road dinosaur expedition of 1992 which concentrated on the area around Mazong Shan.

Contents 1 Geology 1.1 Chijinbao Formation 1.2 Digou Formation 1.3 Zhonggou Formation 2 Vertebrate Fauna 2.1 Ceratopsians 2.2 Crocodilians 2.3 Fish 2.4 Ornithopods 2.5 Pterosaurs 2.6 Saurischians 2.7 Thyreophorans 2.8 Turtles 3 See also 4 References

Geology

The Group is made up of three main formations.

Chijinbao Formation

This consists of a lower Red Unit of coarse conglomerates grading to fine sandstones representing river channel to alluvial fan deposits, and an upper unit of red clastic sediments from either overbank deposits in a meandering fluvial environment, or accumulation in a shallow lacustrine or paludal (marsh) environment.

Digou Formation

This consists of grey siltstones and calcareous mudstones comprising two sequences of fluvio-lacustrine sedimentation with some alluvial fan and littoral (lake-shore) deposits.

Zhonggou Formation

This consists of red siltstones and mudstones in a series of upwardly coarsening cycles of lacustrine sediments.

Vertebrate Fauna

Ceratopsians

Ceratopsians reported from the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Archaeoceratops	Archaeoceratops oshimai			"[Two] individuals lacking forelimbs."[1]
Auroraceratops	Auroraceratops rugosus
Microceratus	Microceratus gobiensis
	Microceratus sulcidens
Psittacosaurus	Psittacosaurus mazongshanensis			"One individual lacking caudal and hindlimb."[1]

Crocodilians

Indeterminate crocodilian remains are known from the group.

Crocodilians reported from the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Chiayusuchus	Chiayusuchus cingulatus

Fish

Ray-finned fishes reported from the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Xixiaichthys	Xixiaichthys tongxinensis

Ornithopods

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative data are in small text; crossed out data are discredited.

Ornithopods reported from the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Equijubus	Equijubus normani			"Skull and partial postcranial skeleton."[2]	(both this and Probactrosaurus are properly hadrosauroids rather than hadrosaurids)
Probactrosaurus	Probactrosaurus mazongshanensis			"Partial skull and postcranial skeleton."[3]
Siluosaurus	Siluosaurus zhangqiani			"Teeth."[4]	Nomen dubium, tentatively classified as a Hypsilophodontid.

Pterosaurs

Pterosaurs reported from the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Material	Notes
Noripterus	Indeterminate

Saurischians

Indeterminate allosaurid, dromaeosaurid, and ornithomimmid, remains are known from the Xinminbao Group. Indeterminate nemegtosaurid remains are also known from the group.

Saurischians reported from the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Asiatosaurus	Asiatosaurus mongoliensis
Chiayusaurus
Gobititan	Gobititan shenzhouensis
Nanshiungosaurus	Nanshiungosaurus bohlini			"[Sixteen] cervical and dorsal vertebrae."[5]	This species may not belong in Nanshiungosaurus.
Sinornithoides	Indeterminate

Thyreophorans

Indeterminate ankylosaur remains are known from the group.

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative data are in small text; crossed out data are discredited.

Thyreophorans of the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Heishansaurus	Heishansaurus pachycephalus				(nomen dubium - originally described as, and may be, a pachycephalosaur)
Stegosaurides	Stegosaurides excavatus				(nomen dubium)

Turtles

Turtles of the Xinminbao Group
Genus	Species	Location	Stratigraphic position	Abundance	Notes
Tsaotanemys	Tsaotanemys rugosus

See also

• List of dinosaur-bearing rock formations

References

• A new Psittacosaur (Psittacosaurus mazongshanensis sp. nov.) from Mazongshan area, Ganzu Province. Xu, X. Sino-Japanese Silk Road dinosaur expedition., Dong, Z. (ed). China Ocean press; 48-67 (1997).
• Biostratigraphy and palaeoenvironment of the dinosaur-bearing sediments in Lower Cretaceous of Mazongshan area, Gansu Province, China. Tang, F., Luo, Z., Zhou, Z., You, H., Georgi, J., Tang, Z., and Wang. X. Cretaceous Research 22, 115-129 (2001).