Part 1 Printing the Circuit Board. 1. Choose a method to use for creating the PCB. Your choice will usually be based on the availability of materials needed by the method, the technical difficulty level of the method or the quality of PCB you desire to obtain.
Permian-Triassic Extinction. In this video segment from Evolution: Extinction!, geologist Peter Ward shows rock layers laid down during the Permian and Triassic periods. The Permian layers contain abundant animal fossils and fossilized traces of animals, while the Triassic layers are almost devoid of fossils, suggesting a mass extinction event occurred 250 million years ago, at the end of the Permian.
As a result, mammals became the dominant species in the Cenozoic Era. The largest mass extinction happened at the end of the Paleozoic Era. The Permian-Triassic mass extinction event saw about 96% of marine life go extinct, along with 70% of terrestrial life.Even insects weren't immune to this mass extinction event like many of the others in history.he largest mass extinction happened at the end of the Paleozoic Era. The Permian-Triassic mass extinction event saw about 96% of marine life go extinct, along with 70% of terrestrial life. Even insects weren't immune to this mass extinction event like many of the others in history.