Hekou Group
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The Hekou Group is a geological group in Gansu Province, China. It is Early Cretaceous in age. Many dinosaur fossils have been recovered from the Hekou Group, including iguanodonts, large sauropods, and armored dinosaurs. Fossil eggs are rare, but one oogenus, Polyclonoolithus, was discovered in the Hekou Group.[2] Extensive fossil tracks belonging to pterosaurs and dinosaurs have also been described.[3][4] The group spans the Valanginian to Albian and can be subdivided into four formations.[1]
TypeGeologic group
Sub-unitsHuazhuang Formation,
Hongkoucheng Formation,
Yanguoxia Formation,
Zhujiatai Formation
Hongkoucheng Formation,
Yanguoxia Formation,
Zhujiatai Formation
UnderliesUnconformity: Minhe Formation
OverliesUnconformity: Xiangtang Formation
| Hekou Group | |
|---|---|
| Stratigraphic range: Early Cretaceous,[1] | |
| Type | Geologic group |
| Sub-units | Huazhuang Formation, Hongkoucheng Formation, Yanguoxia Formation, Zhujiatai Formation |
| Underlies | Unconformity: Minhe Formation |
| Overlies | Unconformity: Xiangtang Formation |
| Thickness | 3,700 m (12,100 ft) |
| Lithology | |
| Primary | Sandstone, mudstone, conglomerate |
| Location | |
| Coordinates | 35.9°N 103.3°E |
| Approximate paleocoordinates | 34.8°N 103.1°E |
| Region | Gansu |
| Country | China |
| Extent | Longzhong Basin |
  Hekou Group (China)  Hekou Group (Gansu) | |
Fossil content
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Dinosaurs
Ornithopods
| Ornithopods of the Hekou Group | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Lanzhousaurus[5] | L. magnidens | A partial skeleton including the mandible, maxillary teeth, dentary teeth, cervical and dorsal vertebrae, sternal plates, ribs, and pubes | A large styracosternan iguanodontian |  | ||
Sauropods
| Sauropods of the Hekou Group | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Daxiatitan[6] | D. binglingi | A partial skeleton including cervical, dorsal, and caudal vertebrae, ribs, and a haemal arch, scapulocoracoid, and femur | A titanosaurian sauropod |  | ||
| Huanghetitan[7] | H. liujiaxiaensis | A partial skeleton including caudal vertebrae, a partial sacrum and ribs, and the left shoulder girdle | A somphospondylian sauropod |  | ||
| Yongjinglong[8] | Y. datangi | A partial skeleton including teeth, cervical and dorsal vertebrae, a rib, the left scapulocoracoid, and the right ulna and radius | A euhelopodid somphospondylian |  | ||
Thyreophorans
| Thyreophorans of the Hekou Group | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Stegosaurinae[9] | Indeterminate | A partial skeleton including cervical and dorsal vertebrae, ribs, a right forelimb (including a partial humerus, ulna, and radius), and one dermal plate[10] | An unnamed stegosaurid distinct from Wuerhosaurus and Stegosaurus stenops. | |||
| Taohelong[11] | T. jinchengensis | A partial skeleton including ribs, a left ilium, a caudal vertebra, and part of the sacral shield | A polacanthine nodosaurid | |||
Fish
Ray-finned Fish
| Ray-finned Fish of the Helou Group | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Sinamia[12] | S. lanshoensis | Many well-preserved specimens as part and counterpart fossils | A sinamiid amiiform | |||