Paleozoic
WordNet
adjective
(1) Of or relating to or denoting the Paleozoic era
noun
(2) From 544 million to about 230 million years ago
WiktionaryText
Adjective
- Of a geologic era within the Phanerozoic eon and comprises the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian periods from about 542 to 250 million years ago, from the age of trilobites to that of reptiles.