Sheinwoodian
In the geologic timescale, the Sheinwoodian is the age of the Wenlock epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that is comprehended between 433.4 ± 0.8 Ma and 430.5 ± 0.7 Ma (million years ago), approximately. The Sheinwoodian age succeeds the Telychian age and precedes the Homerian age.[4]
| Sheinwoodian | |
|---|---|
| 433.4 ± 0.8 – 430.5 ± 0.7 Ma | |
| Chronology | |
Epochs in the Silurian -444 — – -442 — – -440 — – -438 — – -436 — – -434 — – -432 — – -430 — – -428 — – -426 — – -424 — – -422 — – -420 — – -418 — Epochs of the Silurian Period. Axis scale: millions of years ago. | |
| Etymology | |
| Name formality | Formal |
| Name ratified | 1980[3] |
| Usage information | |
| Celestial body | Earth |
| Regional usage | Global (ICS) |
| Time scale(s) used | ICS Time Scale |
| Definition | |
| Chronological unit | Age |
| Stratigraphic unit | Stage |
| Time span formality | Formal |
| Lower boundary definition | Imprecise. Currently placed between acritarch biozone 5 and LAD of Pterospathodus amorphognathoides. See Llandovery for more info. |
| Lower boundary definition candidates | A conodont boundary (Ireviken datum 2) which is close to the murchisoni graptolite biozone. |
| Lower boundary GSSP candidate section(s) | None |
| Lower boundary GSSP | Hughley Brook, Apedale, UK 52.5811°N 2.6389°W |
| GSSP ratified | 1980[3] |
| Upper boundary definition | FAD of the Graptolite Cyrtograptus lundgreni |
| Upper boundary GSSP | Sheinton Brook, Homer, England 52.6156°N 2.5647°W |
| GSSP ratified | 1980[3] |
Definition
The Wenlock-Llandovery boundary is defined by the first occurrence of Cyrtograptus centrifugus. The stage is named after Sheinwood village, north of Much Wenlock. The Buildwas Formation of Shropshire, United Kingdom contains the type section.[5]
Palaeontology
Arthropods
| Arthropods of the Sheinwoodian | ||||
|---|---|---|---|---|
| Taxa | Presence | Location | Description | Images |
| Balizoma | Sheinwoodian to Gorstian | Dudley, England | A trilobite with nodular tubercles on its cephalon | _of_the_encrinurine_trilobite_Balizoma_variolaris.jpg.webp) |
Cephalopods
| Cephalopods of the Sheinwoodian | ||||
|---|---|---|---|---|
| Taxa | Presence | Location | Description | Images |
| Cameroceras | Dapingian-Homerian | |||
References
- Jeppsson, L.; Calner, M. (2007). "The Silurian Mulde Event and a scenario for secundo—secundo events". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 93 (02): 135–154. doi:10.1017/S0263593300000377.
- Munnecke, A.; Samtleben, C.; Bickert, T. (2003). "The Ireviken Event in the lower Silurian of Gotland, Sweden-relation to similar Palaeozoic and Proterozoic events". Palaeogeography, Palaeoclimatology, Palaeoecology. 195 (1): 99–124. doi:10.1016/S0031-0182(03)00304-3.
- Holland, C. (1982). "The State of Silurian Stratigraphy" (PDF). Episodes. 1982: 21–23. Retrieved 11 December 2020.
- Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. ISBN 9780521786737.
- Silurian System
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