The Paleozoic Era is a geologic era that lasted from 541 to 251.902 million years ago. This is divided into six geologic periods: the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The swamps that were turned into coal over time grew during the Carboniferous period, which expands from 358.9 million years ago to 298.9 million years ago. The period is well-known because many coal beds were formed during that time period. During the Carboniferous, terrestrial animals were well-established. It ended with a minor extinction event known as the Carboniferous rainforest collapse.
The fossils are found in sedimentary rocks such as sandstone, limestone and even coal. This type of rock tends to be in very deep layers and for this reason they are easier to house the fossils. they are formed by the melting of other rocks.
