Paleozoic

/ˈpeɪliəˌzoʊɪk/

The Paleozoic is the earliest era of the Phanerozoic eon, lasting from about 541 to 252 million years ago. The Paleozoic is sometimes referred to as the "Age of Ancient Life."

The Paleozoic was named in the 19th century by geologist Adam Sedgwick from the Greek palaios, "old," and zoe, "life." Lasting nearly 300 million years, this era saw life migrate from the oceans to establish the first land plants, insects, and amphibians. By its end, Earth's continents had merged into the supercontinent Pangea. The era concluded with a mass extinction that wiped out most species, including the majority of marine invertebrates, clearing the way for the rise of the dinosaurs in the following Mesozoic era.

Definitions of Paleozoic

1. adjective

   denoting or relating to the first Phanerozoic era, from about 541 to 252 million years ago
2. noun

   the era of geologic time from about 541 to 252 million years ago; the first Phanerozoic era
   synonyms: Paleozoic era

   example of:

   era, geological era

   a major division of geological time; an era is usually divided into two or more periods