What's the difference between i.e. and e.g.?
1841, "pertaining to the uppermost strata of the Paleozoic era," named by British geologist Sir Roderick Impey Murchison (1792-1871) for the region of Perm in northwestern Russia, where rocks from this epoch are found.
The seventh and last period of the Paleozoic Era, from about 286 to 245 million years ago. During the Permian Period the supercontinent Pangaea, comprising almost all of today's landmasses, formed. Gymnosperms evolved, the first modern conifers appeared, and reptiles diversified. The Permian Period ended with the largest known mass extinction in the history of life. It wiped out nearly 90 percent of known marine life forms. See Chart at geologic time.