Browsing the "Ordovician" Category

The Ordovician period is a division of earth’s history spanning from around 485 to 443 million years ago, and during which life continued to diversify following the Cambrian ‘explosion’. During the Ordovician, planktonic organisms increased in diversity, corals became common and the first vertebrates flourished. The continents were largely confined to the southern hemisphere, however they were rapidly drifting apart and northwards owing to an increase in production of new ocean crust. The Ordovician was a period of mountain building and volcanism owing to the gradual closing of the Iapetus Ocean, which separated the ancient super-continents of Laurentia and Gondwana. Sea levels reached 200 meters above present during the Ordovician, meaning much of the continental landmasses were flooded by shallow seas. The end of the Ordovician is characterised by severe glaciations contemporaneous with a major drop in sea level and the second largest extinction event in earth’s history.