US, WASHINGTON (ORDO NEWS) — 450 million years ago, the world was significantly different from the one in which we live today. All creatures then lived mainly in the oceans, and vegetation was just beginning to fill the planet.
Previously, many continents were merged into one called Gondwana. It was formed after the split of the supercontinent Rodinia, which included absolutely all the territories of the world.
444 million years ago, the Ordovician-Silurian glaciation occurred, which caused a large-scale extinction of the inhabitants of the oceans. By some estimates, approximately 85% of creatures have disappeared. Deep sea species were mainly affected.
Extinction took place in two phases. The second came as a result of a significant decrease in oxygen levels in the oceans. In the atmosphere of the Earth, in turn, the level of carbon dioxide decreased almost to zero. Such conditions persisted for 3 million years.
Theories about the lack of oxygen in the oceans at the border of the Ordovician and Silurian periods have recently been confirmed. That’s just scientists can not say what the changes were associated with. Most multicellular creatures could not survive oxygen deficiency.
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