Paleozoic Era, one of the major divisions of geologic time. It began 570,000,000 years ago and ended 240,000,000 years ago. During the era, plant and animal life evolved in the sea and invaded the land.

Paleozoic Era
PeriodBeganLastedAnimal life
Cambrian 543 million years ago53 million yearsTrilobites were common in the sea. Jawless fish appeared. Land was bare.
Ordovician 505 million years ago65 million yearsMollusks and coral were plentiful in the sea. Algae became common.
Silurian 440 million years ago30 million yearsFish developed jaws. Plants appeared on land.
Devonian 410 million years ago50 million yearsFish were plentiful. Insects and amphibians appeared.
Carboniferous 360 million years ago70 million yearsCrustaceans, fish, and amphibians were plentiful. Reptiles appeared. Huge, swampy forests grew. Giant insects lived in the forests.
Permian 290 million years ago39 million yearsSeed plants appeared. Trilobites died out near the period's end.