|1.||of, denoting, or formed in the third period of the Palaeozoic era, between the Ordovician and Devonian periods, which lasted for 25 million years, during which fishes first appeared|
|2.||of or relating to the Silures|
|3.||the Silurian the Silurian period or rock system|
|Silurian (sĭ-lr'ē-ən) Pronunciation Key
The third period of the Paleozoic Era, from about 438 to 408 million years ago. During this time glaciers that formed during the late Ordovician melted, causing sea levels to rise. The first coral reefs, fish with jaws, and freshwater fish appeared, and jawless fish continued to spread rapidly. The first vascular plants also appeared, as did land invertebrates including relatives of spiders and centipedes. See Chart at geologic time.