Radiometric dating of ordovician period Adults cam meet
At first, low-lying sea beds increased diversity, but later glaciation led to mass extinctions as the seas drained and continental shelves became dry land.
The Llanvirn occupies the rest of the Darriwilian, and terminates with it at the base of the Late Ordovician.Invertebrates, namely molluscs and arthropods, dominated the oceans.The Great Ordovician Biodiversification Event considerably increased the diversity of life.This second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs.The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is highly significant.
Fish, the world's first true vertebrates, continued to evolve, and those with jaws may have first appeared late in the period. About 100 times as many meteorites struck the Earth per year during the Ordovician compared with today.