Britannica Educational Publishing 
Paleozoic Era [PDF ebook] 

Characterized by a surge in biodiversity and evolutionary development, the Paleozoic Era ushered in the beginnings of life as we know it. Within these pages, readers will discover the fossil and geologic evidence from this time that reveals a dynamic planet, where new species of plants and animals were constantly emerging and continents were breaking apart and reforming. While many of the species from this era are now extinct and the continents are relatively stable, remnants of this era still continue to shed much-needed light on the conditions of Earth, both past and present.