After The Precambrian mass extinction ancient super continents called Gondawana and Laurasia formed. Roughly 505 million years ago ice caps covered North America. An ice cap is a thick layer of ice and snow that covers about 1900 square miles. Many animals have not adapted to the ice and cold of a glacier. 360 million years ago the Appalachian mountains formed. 250 million years ago the super continent of the southern hemisphere Gondawana and the super continent of the northern hemisphere, Laurasia came together to form the super continent called Pangaea. This happened because of the movement of the tectonic plates. Over 500 million years ago vertebrates arose. The first vertebrate was a fish with no jaw. Roughly 475 million years ago algea evolved to early plants. The early plants generally lived near water and looked like our modern day moss. About 416 million years ago the Earth was heating up and some of the small lakes and rivers where drying up. The lungfish used it's bladder to breath so it could survive. The first insect lived 400 million years ago. It was found in Scotland and called the Rhyniognath Hirst. The earliest amphibian dated back 360 million years ago and was found in Greenland. It was called the Devonian. About 312 million years ago a fossil was found in a tree stump in Nova Scotia. It was a four legged creature known now as an amphibian. The mass extinction ended the Paleozoic Era. Scientists think that it may have been caused by comets, volcanoes, and meteors. The nickname for the Paleozoic Era is "The Explosion of Life". It is called that because a great deal of life was created at this time.