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.
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 The dinosaurs of the Xinminbao Group are collectively referred to as the Mazongshan Dinosaur Fauna, representing a unique dinosaur assemblage from all other known dinosaur faunas.
Ceratopsians Ceratopsians reported from the Xinminbao Group Genus Species Location Stratigraphic position Material Notes ImagesArchaeoceratopsArchaeoceratops oshimai"[Two] individuals lacking forelimbs.""Table 22.1," in Weishampel, et al. (2004). Page 479.AuroraceratopsAuroraceratops rugosusMicroceratusMicroceratus gobiensisMicroceratus sulcidensPsittacosaurusPsittacosaurus mazongshanensis"One individual lacking caudal and hindlimb."
Ornithopods
Ornithopods reported from the Xinminbao Group Genus Species Location Stratigraphic position Material Notes ImagesEquijubusEquijubus normani"Skull and partial postcranial skeleton.""Table 19.1," in Weishampel, et al. (2004). Page 415. (both this and Probactrosaurus are properly hadrosauroids rather than hadrosaurids)GongpoquansaurusH.-l. You et al. (in press). "Gongpoquansaurus mazongshanensis (Lü, 1997) comb. nov. (Ornithischia: Hadrosauroidea) from the Early Cretaceous of Gansu Province, northwestern China". In David A. Eberth and David C. Evans (eds). Hadrosaurs: Proceedings of the International Hadrosaur Symposium. Indiana University Press. .Gongpoquansaurus mazongshanensis"Partial skull and postcranial skeleton.""Table 19.1," in Weishampel, et al. (2004). Page 417.SiluosaurusSiluosaurus zhangqiani"Teeth.""Table 18.1," in Weishampel, et al. (2004). Page 396.Nomen dubium, tentatively classified as a Hypsilophodontid.
Saurischians
Saurischians reported from the Xinminbao Group Genus Species Location Stratigraphic position Material Notes ImagesAsiatosaurusAsiatosaurus mongoliensisBeishanlongBeishanlong grandisA deinocheirid ornithomimosaur.ChiayusaurusC. lacustris GobititanGobititan shenzhouensis"Nanshiungosaurus""Nanshiungosaurus bohlini" "[Sixteen] cervical and dorsal vertebrae."This species does not belong to Nanshiungosaurus.SinornithoidesIndeterminate
Thyreophorans Indeterminate ankylosaur remains are known from the group.
Thyreophorans of the Xinminbao Group Genus Species Location Stratigraphic position Abundance NotesStegosauridesStegosaurides excavatus (nomen dubium)
Crocodilians Indeterminate crocodilian remains are known from the group.
Crocodilians reported from the Xinminbao Group Genus Species Location Stratigraphic position Material Notes ImagesChiayusuchusChiayusuchus cingulatus
Fish Ray-finned fishes reported from the Xinminbao Group Genus Species Location Stratigraphic position Material Notes ImagesXixiaichthysXixiaichthys tongxinensis
Pterosaurs Pterosaurs reported from the Xinminbao Group Genus Species Location Stratigraphic position Material Notes Images NoripterusIndeterminate
Turtles Turtles of the Xinminbao Group Genus Species Location Stratigraphic position Abundance NotesTsaotanemysTsaotanemys rugosus
See also
List of dinosaur-bearing rock formations
References
Further reading 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).