The Ulansuhai Formation is a geological formation in Inner Mongolia, north China. Dinosaur remains are among the fossils that have been recovered from the formation.

The Ulansuhai Formation has traditionally been considered to date to the Aptian

Aptian

The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...

-Albian

Albian

The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...

 stages of the Late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

, due to similarities between the Ulansuhai fauna and known Aptian formations. However, radiometric dating

Radiometric dating

Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...

 done on underlying formations has shown this to be incorrect. Due to the age of underlying rocks, the Ulansuhai Formation cannot be older than the Turonian

Turonian

The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...

 stage of the Late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

, about 92 Ma.

Dinosaurs

Dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s of the Ulansuhai Formation
Taxa	Presence	Description	Images
Chilantaisaurus tashuikouensis Chilantaisaurus Chilantaisaurus is a genus of neovenatorid theropod dinosaur from the late Cretaceous Ulansuhai Formation of China . The type species, C. tashuikouensis, was described by Hu in 1964. Chilantaisaurus was a large theropod, estimated as weighing between and...		A Neovenatorid. "Fragmentary postcranial skeleton."
Gobisaurus domoculus Gobisaurus Gobisaurus is an extinct genus of basal ankylosaurid ankylosaur from the Upper Cretaceous Ulansuhai Formation of China. The holotype consists of a skull and as yet undescribed postcranial remains. It was first named by Matthew K. Vickaryous, Anthony P. Russell, Philip J...		An ankylosaur Ankylosauridae An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs that evolved 125 million years ago and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event... . "Skull [and possible] postcranium."
Shaochilong maortuensis Shaochilong Shaochilong is a genus of carcharodontosaurid dinosaur from the mid Cretaceous Ulansuhai Formation of China . The type species, S...		A carcharodontosaurid Carcharodontosauridae Carcharodontosaurids were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, in modern paleontology this name indicates a clade within Carnosauria... , formerly Chilantaisaurus maortuensis.
Sinornithomimus dongi Sinornithomimus Sinornithomimus is a genus of ornithomimid theropod dinosaur found in 1997, in the early Late Cretaceous strata of the Ulansuhai Formation located at Alshanzuo Banner, Nei Mongol Autonomous Region, Northern China.-Discovery and naming:...		An ornithomimid. "[Fourteen] skeletons, juvenile to adult."
Indeterminate Iguanodontian