John P. Rafferty, "The Paleozoic Era: Diversification of Plant and Animal Life"

John P. Rafferty, "The Paleozoic Era: Diversification of Plant and Animal Life"
Rosen Education Service | 2010 | ISBN: 1615301119, 1615301968 | 339 pages | PDF | 6,3 MB

Introduction:

The Paleozoic Era is probably less familiar and perhaps

less dramatic than the age of the dinosaurs that would

dominate the Mesozoic Era that followed. However, the

Paleozoic Era contained one of the most intense increases

in biodiversity in Earth’s history, the Cambrian explosion

and the subsequent Ordovician radiation. It also contained

the largest extinction event the world has ever

known, the Permian extinction, which wiped out more

than 90 percent of marine species and roughly 70 percent

of species on land. It was also a time of great geological

changes as landmasses migrated and collided, eventually

creating the supercontinent called Pangea. Sea levels rose,

drowning whole continents, fell, and rose again. Some of

Earth’s oldest mountain ranges, such as the Appalachians

and the Urals, were formed during the Paleozoic. Life

moved from the oceans to dry land and insects took wing

for the first time. Many evolutionary advances took place,

which set the stage for life as we know it today. Some of

these advances include the development of plants with

seeds, shelled eggs, and organisms capable of breathing

air. So in geologic history the Paleozoic Era was pretty

dramatic after all. In the pages that follow, all of these

developments, as well as the clues that scientists have used

to decipher the history of Earth’s changes, will be explored.

Spanning nearly 300 million years of history, from 542

to 251 million years ago, the Paleozoic Era covers more

than half of the Phanerozoic Eon, also known as the Age

of Life—the geologic time in which humans still live.

Scientists divide the Paleozoic into a number of smaller

periods, beginning with the Cambrian, approximately 542

million to 488 million years ago, followed by the

Ordovician, Silurian, Devonian, Carboniferous, and

Permian periods. Most of these names are derived from

the locations in which rocks and fossils from that time

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