What Do Paleozoic, Mesozoic, and Cenozoic Mean?
Paleozoic, Mesozoic, and Cenozoic refer to the three main eras of complex multicellular life on Earth — in Greek, the words mean “ancient life,” “middle life,” and “new life.” The Paleozoic stretches from 542 to 251 million years ago, the Mesozoic from 251 to 65.5 million years ago, and the Cenozoic from 65.5 million years ago to the present. Speaking in extremely broad terms, the Paleozoic might be considered the age of invertebrates, land plants, amphibians, and synapsids (the ancestors of mammals), the Mesozoic was the Age of Reptiles (especially dinosaurs), and the Cenozoic is the Age of Mammals. Since the terms were coined, it has been discovered that complex multicellular life did actually exist about 60 million years before the start of the Paleozoic. This life is referred to as the Ediacaran fauna. The Paleozoic began about 542 million years ago, when the land was devoid of life and all living things were aquatic. The oceans were filled with small, simple organisms such as tri
