Xīnmínbǎo Group 新民堡群 | |
Type: | Geological formation |
Age: | Late Barremian-Aptian |
Period: | Aptian |
Prilithology: | Conglomerate, siltstone, mudstone |
Otherlithology: | Sandstone |
Region: | East Asia |
Country: | |
Subunits: | Chijinbao Formation, Digou Formation, Xiagou Formation, Zhonggou Formation |
The Xīnmínbǎo 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 Gōngpóquán (公婆泉) and Suànjǐngzi (算井子) 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.
The group is made up of three main formations.
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.
This consists of grey siltstones and calcareous mudstones comprising two sequences of fluvio-lacustrine sedimentation with some alluvial fan and littoral (lake-shore) deposits.
This consists of red siltstones and mudstones in a series of upwardly coarsening cycles of lacustrine sediments.
Ceratopsians reported from the Xinminbao Group | ||||||
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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." | ||||
Indeterminate crocodilian remains are known from the group.
Ornithopods reported from the Xinminbao Group | ||||||
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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) | |||
Gongpoquansaurus[3] | date= (help) | Gongpoquansaurus mazongshanensis | "Partial skull and postcranial skeleton."[4] | |||
Siluosaurus | Siluosaurus zhangqiani | "Teeth."[5] | Nomen dubium, tentatively classified as a Hypsilophodontid. | |||
Saurischians reported from the Xinminbao Group | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Asiatosaurus | Asiatosaurus mongoliensis | |||||
Beishanlong | Beishanlong grandis | A deinocheirid ornithomimosaur. | ||||
Chiayusaurus | C. lacustris | |||||
Gobititan | Gobititan shenzhouensis | |||||
"Nanshiungosaurus" | "Nanshiungosaurus bohlini" | "[Sixteen] cervical and dorsal vertebrae."[6] [7] | This species does not belong to Nanshiungosaurus.[8] | |||
Sinornithoides | Indeterminate | |||||
Indeterminate ankylosaur remains are known from the group.