Ulansuhai Formation
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-Albian stages of the Lower Cretaceous, due to similarities between the Ulansuhai fauna and known Aptian formations. However, radiometric dating 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 stage of the Late Cretaceous, about 92 Ma. Evans et al. suggested that the formation is likely dated to the Santonian-Campanian ages or older, but younger than.