Eras

Question 1

Paleozoic Era: Early Paleozoic Cambrian and Ordovician Periods

Age of Invertabrates
Continents covered by large, shallow inland seas
No life existed on land
Ordovician period ended with mass extinction

Answer 1

Paleozoic Era: Middle Paleozoic Silurian and Devonian Periods

Age of fishes
Some invertabrates lived on land, such as cockroaches and dragonflies
Continents collided forming mountain ranges