Phanerozoïcum

Phanerozoïcum, typically known in English as the Phanerozoic, is the current eon of the geologic time scale. It spans from about 541 million years ago to the present and is characterized by abundant, easily fossilized life. The name comes from Greek phaneros meaning visible and zoe meaning life, reflecting the onset of a well-preserved fossil record that distinguishes this interval from the Precambrian.

The Phanerozoïcum is divided into three major eras: Paleozoic, Mesozoic, and Cenozoic. The Paleozoic (approx. 541–252 million years ago) saw the rise of diverse marine communities, the colonization of land by plants and animals, and several mass extinctions, including the end-Permian event. The Mesozoic (approx. 252–66 million years ago) is known as the age of dinosaurs, along with the evolution of early birds and mammals, and ends with the Cretaceous–Paleogene extinction. The Cenozoic (approx. 66 million years ago to the present) features major mammalian and avian radiations, climatic shifts, plate tectonic rearrangements, and the appearance of humans in the late Neogene/Quaternary.

Geologically, the base of the Phanerozoïcum is defined at the base of the Cambrian, marked by the first appearance of Treptichnus pedum (the GSSP at Fortune Head, Newfoundland), about 541 million years ago. The upper boundary remains the present. The Phanerozoic records the rapid development of complex multicellular life and forms the framework for modern biostratigraphy and paleontology.