Xinminbao Group

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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.

Geology[edit]

The Group is made up of three main formations.

Chijinbao Formation[edit]

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[edit]

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[edit]

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

Vertebrate Fauna[edit]

Ceratopsians[edit]

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[edit]

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[edit]

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

Xixiaichthys

Xixiaichthys tongxinensis

Ornithopods[edit]

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.
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[edit]

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

Noripterus

Indeterminate

Saurischians[edit]

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[edit]

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 taxa are in small text; crossed out taxa 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[edit]

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

Tsaotanemys

Tsaotanemys rugosus

See also[edit]

References[edit]

  1. ^ a b "Table 22.1," in Weishampel, et al. (2004). Page 479.
  2. ^ "Table 19.1," in Weishampel, et al. (2004). Page 415.
  3. ^ "Table 19.1," in Weishampel, et al. (2004). Page 417.
  4. ^ "Table 18.1," in Weishampel, et al. (2004). Page 396.
  5. ^ "Table 7.1," in Weishampel, et al. (2004). Page 152.
  • 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).