Imagine a horizontal timeline extending from the far left (∼4.5 BYA) to the right (Present). The timeline is divided into color‐coded segments reflecting the major geologic divisions: Archean (Dark gray): (4 billion to 2.5 billion years ago) Proterozoic (Deep blue): (2.5 billion to 541 million years ago) Phanerozoic Eon: (541 million years ago to present). This eon is divided into three eras: Paleozoic, Mesozoic, and Cenozoic Paleozoic (Green to Orange gradient): (541 to 252 million years ago) Mesozoic (Rusty red/orange): (252 to 66 million years ago) Cenozoic (Vibrant blue/green): (66 million years ago to present) See more