In the geologic timescale , the Telychian is the third and final age of the Llandovery Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon . The Telychian Age was between 438.5 ± 1.2 million years ago (Ma) and 433.4 ± 0.8 Ma. The Telychian Age succeeds the Aeronian Age and precedes the Sheinwoodian Age. The name of the interval is derived from the Pen-lan-Telych Farm near Llandovery , Powys, Wales .
4-631: It ended with the Ireviken event . The Ireviken event was the first of three relatively minor extinction events (the Ireviken, Mulde , and Lau events) during the Silurian Period. It occurred at the Llandovery / Wenlock boundary (mid Silurian, 433.4 ± 0.8 million years ago ). The event is best recorded at Ireviken , Gotland , where over 50% of trilobite species became extinct; 80% of
8-477: Is best recorded at Ireviken , Gotland , where over 50% of trilobite species became extinct; 80% of the global conodont species also became extinct in this interval. The event lasted around 200,000 years, spanning the base of the Wenlock epoch. It is associated with a period of global cooling. It comprises eight extinction "datum points"—the first four being regularly spaced, every 30,797 years, and linked to
12-516: The Milankovic obliquity cycle. The fifth and sixth probably reflect maxima in the precessional cycles, with periods of around 16.5 and 19 ka. The final two data are much further spaced, so harder to link with Milankovic changes . The mechanism responsible for the event originated in the deep oceans, and made its way into the shallower shelf seas. Correspondingly, shallow-water reefs were barely affected, while pelagic and hemipelagic organisms such as
16-519: The global conodont species also become extinct in this interval. This geochronology article is a stub . You can help Misplaced Pages by expanding it . Ireviken event The Ireviken event was the first of three relatively minor extinction events (the Ireviken , Mulde , and Lau events) during the Silurian period. It occurred at the Llandovery / Wenlock boundary (mid Silurian, 433.4 ± 0.8 million years ago ). The event
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