At this point Xin didn't stop and continued to tell Jia about the different periods. Next on queue was the Silurian Period. Silurian Period, in geologic time, the third period of the Paleozoic Era. It began 443.8 million years ago and ended 419.2 million years ago, extending from the close of the Ordovician Period to the beginning of the Devonian Period.
The Silurian lasted about 28 million years. There was a rapid recovery of biodiversity after the great extinction event at the end of the Ordovician.
A warm climate and high sea level gave rise tolarge reefs in shallow equatorial seas. Tabulate corals and stromatoporid sponges were the main builders of these first coral based reefs, but rugose corals and recepticulite algae also contributed. Invertebrates remained dominant because vertebrates were relatively rare.
Sea scorpions (euryptids) reached their maximum diversity. These predators were commonly 5–9 inches long.
