Phanerozoic

The current eon, beginning about 541 million years ago and continuing to the present, defined by the abundant fossil record of complex, hard shelled and skeletal life that gives the eon its name, meaning visible life. Includes the Phanerozoic eon itself, its three constituent eras (Paleozoic, Mesozoic, Cenozoic), and every period and epoch formally nested within those eras in the standard geologic time scale, from the Cambrian through the present-day Holocene within the Quaternary. Belongs here: the Phanerozoic eon and any era, period or epoch formally nested inside it. Does not belong here: the Proterozoic eon that precedes it, whose rock record predates the abundant hard bodied fossils that define the Phanerozoic boundary.