Paleozoic Life History - The Changing Earth: Exploring Geology and Evolution - page 560

OUTLINE
Introduction
What Was the Cambrian Explosion?
The Emergence of a Shelly Fauna
Paleozoic Invertebrate Marine Life
Vertebrate Evolution
GEO-INSIGHT: Trilobites—Paleozoic Arthropods
Fish
Amphibians—Vertebrates Invade the Land
Evolution of the Reptiles—The Land Is Conquered
Plant Evolution
GEO-FOCUS: Palynology: A Link Between Geology and Biology
Geo-Recap

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OBJECTIVES
At the end of this chapter, you will have learned that
Animals with skeletons appeared abruptly at the beginning
of the Paleozoic Era and experienced a short period of rapid
evolutionary diversifi cation.
During the Paleozoic Era, the invertebrates experienced times
of diversifi cation followed by extinction, culminating in the
greatest recorded mass extinction in Earth's history at the end
of the Permian Period.
Vertebrates fi rst evolved during the Cambrian Period, and fi sh
diversifi ed rapidly during the Paleozoic Era.
Amphibians fi rst appear in the fossil record during the Late
Devonian, having made the transition from water to land, and
became extremely abundant during the Pennsylvanian Period
when coal-forming swamps were widespread.
The evolution of the amniote egg allowed reptiles to colonize
all parts of the land beginning in the Late Mississippian.

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