Answer: devonian

AnswerCrossword Clue
DEVONIANPeriod in which amphibians and insects appeared
devonianthe Devonian Period or System
devoniannoting or pertaining to a period of the Paleozoic Era, 405 to 345 million years ago, characterized by the dominance of fishes and the advent of amphibians and ammonites
devonianrelating to a type of rock formed in the fourth period of the Palaeozoic era
devonianof or pertaining to Devonshire, England