Phanerozoic fauna
The Phanerozoic is the current eon in the geologic time scale, corresponding to the Phanerozoic eonothem. It began after the end of the Ediacaran period of the Proterozoic eon, at about 538.8 ± 0.2 million year ago (IUGS 2023), and is split into three geologic eras: the Paleozoic, the Mesozoic, and the Cenozoic. Overall, it contains twelve periods (The Cambrian, the Ordovician, the Silurian, the Devonian, the Carboniferous, the Permian, the Triassic, the Jurassic, the Cretaceous, the Paleogene, the Neogene, and the Quaternary). It is the current geological eon in the geologic time scale when complex animal life evolved, such as fishes and arthropods, land plant and animal life evolved, including amphibians, reptiles, birds, and mammals, the Great Dying occurred, the dinosaurs evolved, the mammals took over from then, humans later evovled and and began populating Earth.
Definition[]
Trichophycus pedum, a marker of the base of the Phanerozoic
The Global Stratotype Section and Point (GSSP) of the Phanerozoic eonothem as well as the Paleozoic erathem, the Cambrian system, the Terreneuvian series and the Fortunian stage was ratified in 1992. The lower boundary was fixed in the section of Fortune Head on the island of Newfoundland, Canada, and the First Appearing Datum (FAD) of the ichnospecies Trichophycus pedum is related to it.[1] As of 2024, Phanerozoic is the only eonothem with GSSP. It is assumed that the GSSP will also be defined for the Proterozoic eon.[2]