Palaeozoic

The era of geological time between about 570 and 225 million years ago that succeeds the Precambrian and precedes the Mesozoic. It is subdivided into six periods, the *Cambrian , *Ordovician , and *Silurian (lower Palaeozoic), and the *Devonian , *Carboniferous , and *Permian (upper Palaeozoic). See also geological time scale.