Aeronian
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.
| Aeronian | |||||||||||||
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| Chronology | |||||||||||||
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| Etymology | |||||||||||||
| Name formality | Formal | ||||||||||||
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| 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 52.0300°N 3.7000°W | ||||||||||||
| Lower GSSP ratified | 1984 | ||||||||||||
| 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 51.9700°N 3.7900°W | ||||||||||||
| Upper GSSP ratified | 1984 | ||||||||||||
During the Aeronian the Sedgwickii Event occurred in which graptolite diversity was greatly reduced. This event has been attested in locations such as today's Canada, Libya as well as in La Chilca Formation in Argentina (then part of Gondwana).
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