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The Silurian (/ s ɪ ˈ lj ʊər i. ən, s aɪ-/ sih-LURE-ee-ən, sy-) [8] [9] [10] is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.1 million years ago (), to the beginning of the Devonian Period, 419.62 Mya. [11]
This timeline of Silurian research is a chronological listing of events in the history of geology and paleontology focused on the study of Earth during the span of time lasting from 443.4–419.2 million years ago; the Silurian, and the legacies of this period in the rock and fossil records.
End Triassic: 200 million years ago, 80% of species lost, including all conodonts; End Cretaceous: 66 million years ago, 76% of species lost, including all ammonites, mosasaurs, plesiosaurs, pterosaurs, and nonavian dinosaurs; Smaller extinction events have occurred in the periods between, with some dividing geologic time periods and epochs.
c. 486.85 ± 1.5 Ma – Beginning of the Ordovician and the end of the Cambrian Period. c. 485 Ma – First jawless fish – radiation of Thelodont fish into the Silurian; c. 460 Ma – First crinoids evolve. c. 450 Ma – Late Ordovician microfossils of scales indicate the earliest evidence for the existence of jawed fish or Gnathostomata.
Since the chart combines secular history with biblical genealogy, it worked back from the time of Christ to peg their start at 4,004 B.C. Above the image of Adam and Eve are the words, "In the beginning God created the Heaven and the Earth" (Genesis 1:1) — beside which the author acknowledges that — "Moses assigns no date to this Creation.
The Mulde event was an anoxic event, [4] and marked the second of three 1 relatively minor mass extinctions (the Ireviken, Mulde, and Lau events) during the Silurian period. It coincided with a global drop in sea level, and is closely followed by an excursion [clarification needed] in geochemical isotopes.
[5] [6] Despite its taxonomic severity, the Late Ordovician mass extinction did not produce major changes to ecosystem structures compared to other mass extinctions, nor did it lead to any particular morphological innovations. Diversity gradually recovered to pre-extinction levels over the first 5 million years of the Silurian period. [7] [8 ...
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, 432.9 ± 1.2 million years ago ).