1. The Permian Extinction- 55% of all families on Earth, 96% of marine species, and 70% of terrestrial vertebrae species were killed. Ecosystems took millions of years to be restored. May be the greatest murder mystery in the history of the world.
2. Animals in this period- Edaphosaurus, Dimetrodon, and other pelycosaurs; Eryops, Diplocaulus, archosaurs, amphibians, fish, and lots of invertebrates.
3. Climate- The Permian period presented severe extremes of climate and environment due to its vast size. Some scientists think a series of volcanic eruptions pumped so much debris into the atmosphere that the sun was blocked out, causing a significant drop in temperature.
4. When- This was the last geological period in the Palaeozoic era. It lasted from 299 to 251 million years ago.
5. Plants- Plant life consisted mainly of ferns and seed-ferns, with new plants like conifers and ginkgos coming into prominence. The Glossopteris flora predominating in Gondwanaland (the southern portion of Pangaea). It is gradually replaced by the seed-fern Dicroidium as the climate dries in the Late Permian.
Sources
http://science.nationalgeographic.com/science/prehistoric-world/permian-extinction/
http://www.ucmp.berkeley.edu/permian/permian.php
http://www.livescience.com/43219-permian-period-climate-animals-plants.html