Palaeozoic

The Palaeozoic Era is the first major interval of the Phanerozoic Eon, lasting from about 541 to 252 million years ago. It follows the Neoproterozoic and precedes the Mesozoic. The era is commonly divided into Early Palaeozoic (Cambrian, Ordovician, Silurian, Devonian) and Late Palaeozoic (Carboniferous and Permian) epochs, with regional designations such as Mississippian and Pennsylvanian applied to parts of the Carboniferous in some areas.

The early part of the era is marked by the Cambrian explosion, a rapid diversification of marine animal life and the emergence of many major groups. Marine ecosystems flourished with varied shells and skeletons, and reef communities became important. The following Paleozoic periods saw ongoing marine diversification, along with the first major steps onto land: vascular land plants and various terrestrial arthropods colonized shorelines and moist environments. By the Devonian, often called the “Age of Fish,” jawed fishes diversified and the first tetrapods appeared, signaling a crucial transition toward terrestrial vertebrates.

In the Carboniferous, extensive swamp forests produced large coal deposits and fostered the diversification of seed plants and amniotes, which adapted to drier conditions. The Late Paleozoic witnessed widespread climatic change and the assembly of the supercontinent Pangaea, influencing global biogeography and ecosystem structure. Climate generally cooled toward the end of the era, contributing to ecological stress.

The Palaeozoic ended with the Permian mass extinction, the largest in Earth history, eliminating a substantial portion of marine and terrestrial species and reshaping life on the planet. The era established many enduring lineages and set the stage for the rise of the Mesozoic.