The Silurian is one of the six periods of the Paleozoic era. It spans the time between the Ordovician and the Devonian, about 443 to 417 million years ago. During the Silurian, coral reefs first appeared and fishes underwent rapid and important evolution. Jawless fish became widespread, and freshwater fish and fish with jaws appearance for the first time. The fossil record from this period provides the first good evidence of life on land, including relatives of spiders and centipedes, and also the earliest known vascular plants.