The Paleozoic era comprises from oldest to youngest the following six geologic periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.
At the end of the Paleozoic era, the fossil record includes the first large, sophisticated reptiles and the first modern plants (conifers).
The Paleozoic era is followed by the Mesozoic and Cenozoic eras.
The Paleozoic era covers the time from the first appearance of abundant, hard-shelled fossils to the time when the continents were beginning to be dominated by large, relatively sophisticated reptiles and relatively modern plants.
The division of time into eras dates back to Giovanni Arduino in the eighteenth century, although his original name for the Paleozoic era was called "Primitive."
Throughout the early Paleozoic era, Earth's landmass was broken up into a substantial number of relatively small continents.
Toward the end of the Paleozoic era, the continents gathered together into a supercontinent called Pangea, which included most of Earth's land area.
The start of the Paleozoic era, between roughly 542 mya and 530 mya, is a time when a large number of body plans appears for the first time in the fossil record.
Some scientists theorize that the Phanerozoic eon and also the Paleozoic era began shortly after the breakup of a hypothesized supercontinent at the end of a global ice age.
During the nearly 300 million years of the Paleozoic era, the fossil evidence records dramatic shifts in the forms of life on Earth.