The Bostobe Formation is a geological formation in Qaraghandy & Qyzylorda, Kazakhastan whose strata date back to the Late Cretaceous (Santonian to early Campanian stages, approximately 85 Ma). The sandstones and claystones of the formation were deposited in estuarine, fluvial-lacustrine and fluvial-deltaic environments. Dinosaur remains are among the fossils that have been recovered from the formation. The formation is about 45 m thick and consists primarily of clay with interbeds of sand, representing an estuarine environment.

Fossil content

Khunnuchelys lophorhothon, a trionychid turtle recovered from the formation, was initially thought to belong to a hadrosaurid dinosaur and classified as cf. Lophorhothon sp.