Takatika Grit
Geologic formation in the Chatham Islands, New Zealand
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The Takatika Grit is a geologic formation in Chatham Islands, New Zealand. It preserves fossils dating back to the Paleocene period, although it also preserves disturbed and re-worked Maastrichtian and Campanian microfossils and tetrapod fossils. A 2017 study found that it dated to late Early to Mid Paleocene on the basis of dinoflagellates. It has been subdivided into two informal units, a lower phosphatic unit containing bones and nodular phosphatic layers, and an upper unit with abundant sponge remains and siliceous microfossils.[1]
| Takatika Grit | |
|---|---|
| Stratigraphic range: Late Early to Mid Paleocene | |
| Type | Formation |
| Unit of | Tioriori Group |
| Sub-units | TaP1, TaP2, TaS1, TaS2 |
| Underlies | Tutuiri Greensand |
| Overlies | Chatham Schist |
| Thickness | 5.7 metres exposed |
| Lithology | |
| Primary | Grit, sandstone |
| Location | |
| Region | Chatham Islands (Chatham Island) |
| Country | New Zealand |
Description
The two informal units are further subdivided into two units each, the lower is divided into the lower TaP1 which consists of "poorly sorted, phosphatized grit with abundant phosphorite nodules and bones" and the upper TaP2 which consists of "nodular bedded sandstone and grit". The upper biosiliceous unit is divided into the lower TaS1, which is heavily bioturbated, and the upper TaS2 "characterized by parallel laminations and sinusoidal ripples".[1]
Paleofauna
| Paleofauna of the Takatika Grit | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | |
| Astrophorida indet.[2] | indeterminate | Tioriori | Only fragmentary spicules are known | |||
| Auloplax? (Dactylocalycidae indet.?)[2] | A? sp. | Tioriori | Hexactinellid sponge | |||
| Bacillariophyceae indet.[3] | Indeterminate | Tioriori | Diatoms from the Takatika Grit date back to the Danian and Campanian | |||
| Chlamydoselachus[4] | Indeterminate | Tioriori | ||||
| Dinoflagellata indet.[3] | Indeterminate | Tioriori | Dinoflagellates from the Takatika Grit date back to the Danian and Campanian | |||
| Edaphodon | E. kawai | Tioriori | ||||
| Elasmosauridae indet.[2] | indeterminate | Tioriori | lower (?) Takatika Grit | Almost certainly reworked from older sediments. | ||
| Eotretochone[2] | E. australis | Tioriori | Hexactinellid sponge | |||
| Euretidae indet.[2] | Indeterminate | Tioriori | ||||
| Kupoupou[5] | K. stilwelli | Tioriori | Penguin | |||
| Gastropoda indet.[6] | Indeterminate | Tioriori | ||||
| Lithistida indet.[2] | Indeterminate | Tioriori | Known from scarce weathered fragments | |||
| Lycopodiopsida indet.[7] | Indeterminate | Tioriori | ||||
| Mosasauridae indet.[2] | Indeterminate | Tioriori | lower (?) Takatika Grit | Almost certainly reworked from older sediments. | ||
| Radiolaria indet.[3] | Indeterminate | Tioriori | Radiolarians from the Takatika Grit date back to the Danian and Campanian | |||
| Pararete[2] | P. sp. | Tioriori | Hexactinellid sponge | |||
|
Indeterminate |
Tioriori | lower (?) Takatika Grit | Vertebral centrum, tibia head, proximal pedal phalanx, manual ungual, proximal manual phalanx | Initially suggested to represent evidence of Palaeogene dinosaurs.[8][9][7][10] Almost certainly reworked from older sediments.[1] | ||
| Tretodictyiidae indet.[2] | Indeterminate | Tioriori | ||||
