The topic guide on Paleozoic Life picks up the sections of the chapters on critters ... answering just the part of the question for that time period, and cycling through the questions for each chapter ...

The oldest is the Paleozoic Era, which means ‘ancient life’ and occurred between 541 and 252 million ... The Mesozoic Era ...

3 min read The Cambrian period, part of the Paleozoic era, produced the most ... the world's oceans until they were wiped out in the Permian extinctions about 250 million years ago.

The transition in and out of the Late Paleozoic ice age was one of the ... It also paved the way for the rise of reptiles in the Permian period that followed. I lead an international team of ...