The Tendaguru Formation, or Tendaguru Beds are a highly fossiliferous formation and Lagerstätte in southeastern Tanzania. The formation represents the oldest sedimentary unit of the Mandawa Basin, overlying Neoproterozoic basement, separating by a long hiatus and unconformity. The formation reaches a total sedimentary thickness of more than 110 metres. The formation ranges in age from the late Middle Jurassic to the Early Cretaceous, Oxfordian to Hauterivian stages, with the base of the formation possibly extending into the Callovian.
The Tendaguru Formation is subdivided into six members; from oldest to youngest Lower Dinosaur Member, the Nerinella Member, the Middle Dinosaur Member, Indotrigonia africana Member, the Upper Dinosaur Member, and the Rutitrigonia bornhardti-schwarzi Member. The succession comprises a sequence of sandstones, shales, siltstones, conglomerates with minor oolitic limestones, deposited in an overall shallow marine to coastal plain environment, characterized by tidal, fluvial and lacustrine influence with a tsunami deposit occurring in the Indotrigonia africana Member.