BIO211H5 Lecture Notes - Overfishing, Placodermi, Continental Crust
Document Summary
Where we are today is we re going to be talking about the origin of vertebrates, as well as the origin of jaws. We ll be talking about the ordovician and the silurian periods and a little bit of the devonian. Remember, we re talking about the periods of the palaeozoic. Cambrian explosion, you have the replacement of the cambrian faunas (dominated by trilobites) by the brachiopod faunas. These are little hinged vertebrates related to molluscs. The ordovician goes from 490 to 443 million years ago. It is followed by the silurian 443-417, and the. These are significant because we have radiation of plants and animals from marine environments onto land. In the ordovician, you have a large gondwana, sea-levels are very high, and at the end of the ordovician, there are glaciations. Hence, you go from a greenhouse environment to an icehouse environment. Sitting almost at the equator at this time is the gta.
