The Ulaanoosh Formation, formerly Baruunbayan Formation, is a geologic formation in the Ömnögovi Province of southern Mongolia. The formation dates to the Albian to Cenomanian stages of the Cretaceous. The Ulaanoosh Formation has provided fossils of dinosaurs, turtles and dinosaur eggs assigned to Parafaveoloolithus sp.. In 2020, the neoceratopsian Beg tse was described from the alluvial sandstones, mudstones and conglomerates of the formation.