Lasting from about 485 to 444 million years ago, the Ordovician was the second period of the Paleozoic era. The Ordovician saw a massive boom in marine life and ended with a mass extinction event.
During the Ordovician, oceans filled with diverse species, including 20-foot-long, squid-like cephalopods. The first extensive coral systems formed, as did the first primitive land plants and animals. Mid-period, the breakup of an asteroid caused dramatic meteor showers for millions of years. The period concluded with a severe ice age and mass extinction that wiped out 85 percent of marine species. Geologist Charles Lapworth named the period in 1879 after the Ordovices, an ancient Welsh tribe from the region where its rock layers were first studied.