The Silurian is a geologic period and system that extends from the end of the Ordovician Period , about 443.4 ± 1.5 million years ago ( mya ) , to the beginning of the Devonian Period , about 419.2 ± 3.2 mya ( ICS , 2004 ) .
The Silurian was the period from the end of the Ordovician , about 443.4 million years ago ( mya ) to the beginning of the Devonian period , about 419 mya .