Aeronian
| Aeronian | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chronology | |||||||||||||
| |||||||||||||
| Etymology | |||||||||||||
| Name formality | Formal | ||||||||||||
| 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 | FAD of the Graptolite Monograptus austerus sequens | ||||||||||||
| Lower boundary GSSP | Trefawr Track Section, Llandovery, Wales, UK 52°01′48″N 3°42′00″W / 52.0300°N 3.7000°W | ||||||||||||
| Lower GSSP ratified | 1984[4] | ||||||||||||
| Upper boundary definition | Just above LAD of the Brachiopod Eocoelia intermedia, below FAD of lowest succeeding species Eocoelia curtisi | ||||||||||||
| Upper boundary GSSP | Cefn-cerig Road Section, Llandovery, Wales, UK 51°58′12″N 3°47′24″W / 51.9700°N 3.7900°W | ||||||||||||
| Upper GSSP ratified | 1984[4] | ||||||||||||
In the geologic timescale, the Aeronian is an age of the Llandovery epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that began 440.8 ± 1.2 Ma and ended 438.5 ± 1.1 Ma (million years ago). The Aeronian age succeeds the Rhuddanian age and precedes the Telychian age, all in the same epoch.[5]
GSSP
The GSSP is located in the Trefawr Track section, 500m north of Cwm-coed-Aeron Farm, Wales, UK.[6] The GSSP lies within the gently-dipping blocky mudstones of the Trefawr Formation, which principally yield abundant and diverse shelly faunas, but also contain enough graptolites to allow recognition of several biozones.[7]
Palaeontology
Agnathans
| Agnathans of the Aeronian | ||||
|---|---|---|---|---|
| Taxa | Presence | Location | Description | Images |
| Rhuddanian-Telychian | It had an elongated body and a dorsal fin and an anal fin near the back third of its body. |  | ||
Cephalopods
| Cephalopods of the Aeronian | ||||
|---|---|---|---|---|
| Taxa | Presence | Location | Description | Images |
| Dapingian-Homerian | The shallow seas of Laurentia, Baltica and Siberia.[8] | Head was soft muscular tissue at the opening of hard cone-like shell. |  | |
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.
- ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
- ^ a b Holland, C. (June 1985). "Series and Stages of the Silurian System". 8 (2): 101–103. doi:10.18814/epiiugs/1985/v8i2/005. Retrieved 15 December 2020.
{{cite journal}}: Cite journal requires|journal=(help) - ^ "GSSP Table - All Periods". International Commission on Stratigraphy. Retrieved 2018-09-15.
- ^ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. ISBN 9780521786737.
- ^ "GSSP for Aeronian Stage". International Commission on Stratigraphy. Retrieved September 15, 2018.
- ^ Frey, R.C. 1995. "Middle and Upper Ordovician nautiloid cephalopods of the Cincinnati Arch region of Kentucky, Indiana, and Ohio" (PDF). U.S. Geological Survey, p.73
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