[2][3] It is Haumurian in age according to the New Zealand geologic time scale (mainly Campanian, but ranging from Santonian to lower Maastrichtian).

It forms part of the Upper Cretaceous to Teurian (Danian) (lower Paleocene) Tinui Group.

The aptly named Maungataniwha (Māori for "mountain of monsters") Sandstone Member is known for its rich reptile fossil remains, first investigated by amateur palaeontologist Joan Wiffen.

Because of the lack of material, its exact taxonomic placement is uncertain, although its discoverer Joan Wiffen considered it possibly a megalosaurid, at the time a poorly defined group of unspecialized large carnivorous dinosaurs.

[6][7] Invertebrates found in the formation include beetles,[9] ammonites, annelids, belemnites, bivalves, brachiopods, crinoids, crustaceans, gastropods, nautiloids and scaphopods.