Discoaster
| Discoaster |
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| Discoaster surculus, about 15 μm across | |
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Discoaster
Tan Sin Hok, 1931
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Discoaster is a genus of extinct star-shaped marine algae, with calcareous exoskeletons of between 5-40 μm across that are abundant as nanofossils in tropical deep-ocean deposits of Neogene age. Discoaster belongs to the haptophytes. About 100 species can be recognized.[2]
Biostratigraphic significance
The International Commission on Stratigraphy (ICS) has assigned the extinction of Discoaster brouweri as the defining biological marker for the start of the Calabrian Stage of the Pleistocene, 1.806 million years ago. ICS has assigned the extinction of Discoaster pentaradiatus and Discoaster surculus as the defining biological marker for the start of the Gelasian Stage, 2.588 million years ago, the earliest stage of the Pleistocene. ICS further assigned the extinction of Discoaster kugleri as biological marker for the start of the Tortonian Stage of the Miocene, 11.62 million years ago.
Species
Some species in this genus include:[3] [4]
- D. asymmetricus Gartner
- D. bellus Bukry and Percival
- D. berggrenii Bukry
- D. bollii Martini and Bramlette
- D. brouweri Bramlette and Riedel
- D. calcaris Gartner
- D. exilis Martini and Bramlette
- D. hamatus Martini and Bramlette
- D. intercalaris Bukry
- D. kugleri Martini and Bramlette, 1963
- D. loeblichii Bukry
- D. neohamatus Bukry and Bramlette
- D. neorectus Bukry
- D. pentaradiatus (Tan) Bramlette and Riedel
- D. quintatus Gartner
- D. surculus Martini and Bramlette
- D. toralus Ellis, Lohmann and Wray
- D. triradiatus Tan
- D. variabilis Martini and Bramlette
