The Tahora Formation is a Late Cretaceous geologic formation that outcrops in northeastern New Zealand near Napier. 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. It unconformably overlies the Jurassic to Lower Cretaceous Urewera Group or the Upper Cretaceous Matawai Group. It is conformably overlain by the Haumurian to Teurian Whangai Formation. It consist of three members, the Maungataniwha Sandstone Member, the Mutuera Member and the Houpapa Member. It is named for Tahora Station, south of Matawai in the Gisborne Region. 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.
Depositional environment The whole of the Tinui Group is interpreted to be an upper Cretaceous transgressive sequence. The Maungataniwha Sandstone Member was deposited in a very shallow water to beach environment. The siltstones of the time-equivalent Mutuera Member are thought to have been deposited in a mid to outer shelf environment. The Houpapa Member is interpreted to be the fill of local channels cut into the underlying strata.
Fossil content Vertebrates Indeterminate dinosaur remains have been recovered from the formation, including indeterminate theropod, sauropod, and ornithischian remains.Weishampel, et al. (2004). "Dinosaur distribution". pp. 517-607 in Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.) The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. . pp. 517-607. Other fossils found in the Tahora Formation include plesiosaurs and pterosaurs.Mangahouanga Stream at Fossilworks.org
Because of a lack of material, the exact taxonomic placement of the theropod from the Tahora Formation is uncertain, although its discoverer Joan Wiffen considered it possibly a megalosaurid, at the time a poorly defined group of unspecialized large carnivorous dinosaurs. The vertebra was described by Molnar (1981), and was considered an indeterminate theropod by Agnolin et al. (2010).Molnar, R. E. 1981. "A dinosaur from New Zealand". pp. 91–96 in M. M. Cresswell & P. Vella (eds) Gondwana Five: Proceeding of the Fifth International Gondwanan Symposium. Wellington. A. A., Balkema, Rotterdam.
Reptiles Plesiosaurs Plesiosaurs recorded from Tahora Formation Genus Species Member/Location Material Description ImageTuarangisaurusT. keyesi Maungataniwha Sandstone A nearly complete skull, mandible, rear skull elements, and nine anterior-most cervical vertebrae from the same individual. An elasmosaurid
Mosasaurs Mosasaurs recorded from Tahora Formation Genus Species Member/Location Material Description ImageMoanasaurusM. mangahouangae Maungataniwha Sandstone A disarticulated skull, vertebrae, ribs and flipper bones. A mosasaurin mosasaur
Pterosaurs Pterosaurs recorded from Tahora Formation Genus Species Member/Location Material Description ImageAzhdarchidae indet.Indeterminate Maungataniwha Member, Mangahouanga StreamDistal left ulna, coracoid fragment
Dinosaurs Dinosaurs recorded from Tahora Formation Genus Species Member/Location Material Description ImageAnkylosauria indet. Indeterminate Maungataniwha Member, Mangahouanga Stream An incomplete rib and two caudal veterbral centra Ornithopoda indet. Indeterminate Maungataniwha Member, Mangahouanga Stream Partial right ilium Sauropoda indet. IndeterminateMaungataniwha Member A rib fragment Theropoda indet. Indeterminate Maungataniwha Member, Mangahouanga Stream Caudal vertebra, pedal phalanx
Invertebrates Invertebrates found in the formation include beetles,GS 14182, Mangahouanga Stream (V19/f133) at Fossilworks.org ammonites, annelids, belemnites, bivalves, brachiopods, crinoids, crustaceans, gastropods, nautiloids and scaphopods.
See also List of dinosaur-bearing rock formations List of stratigraphic units with indeterminate dinosaur fossils Geology of the Raukumara region Stratigraphy of New Zealand South Polar region of the Cretaceous
References