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The Late Ordovician mass extinction (LOME), sometimes known as the end-Ordovician mass extinction or the Ordovician-Silurian extinction, is the first of the "big five" major mass extinction events in Earth's history, occurring roughly 445 million years ago (Ma). [1]
The Silurian period has been viewed by some palaeontologists as an extended recovery interval following the Late Ordovician mass extinction (LOME), which interrupted the cascading increase in biodiversity that had continuously gone on throughout the Cambrian and most of the Ordovician. [36] The Silurian was the first period to see megafossils ...
The Ordovician–Silurian extinction events may have been caused by an ice age that occurred at the end of the Ordovician Period, due to the expansion of the first terrestrial plants, [54] as the end of the Late Ordovician was one of the coldest times in the last 600 million years of Earth's history.
The order Dissidocerida was proposed by Zhuravleva (1994) for Dissidoceras undosum Zhuravleva, 1964, a Silurian orthoconic genus with a wide, nearly central, tubular siphuncle, suborthochoanitic septal necks, and endosiphuncular rod; in many aspects similar to rod-bearing orthocones of the Ordovician. It is thought by some that Ordovician ...
Geologists can divide the rocks of the Ordovician and Silurian periods into graptolite biozones; these are generally less than one million years in duration. A worldwide ice age at the end of the Ordovician eliminated most graptolites except the neograptines.
The Tumblagooda Sandstone is a geological formation deposited during the Silurian or Ordovician periods, between four and five hundred million years ago, and is now exposed on the west coast of Australia in river and coastal gorges near the tourist town of Kalbarri, Kalbarri National Park and the Murchison River gorge, [1] straddling the boundary of the Carnarvon and Perth basins. [2]
In the geological timescale, the Llandovery Epoch (from 443.8 ± 1.5 million years ago to 433.4 ± 0.8 million years ago) occurred at the beginning of the Silurian Period. . The Llandoverian Epoch follows the massive Ordovician-Silurian extinction events, which led to a large decrease in biodiversity and an opening up of ecosyste
The Beaverfoot Formation spans the Ordovician-Silurian boundary and records faunal changes that occurred during the Ordovician-Silurian extinction events. It is known for fossil rhynchonellid, atrypid, and pentamerid brachiopods, most of which have undergone silicification and can be separated from the dolomite matrix by treatment with acid.