Which eon spans from about 540 million years ago to the present day and includes eras such as the Paleozoic, Cambrian, and Precambrian?

Which eon spans from about 540 million years ago to the present day and includes eras such as the Paleozoic, Cambrian, and Precambrian?

• A. Archeozoic Eon
• B. Phanerozoic Eon
• C. Proerozoic Eon
• D. Fossils

Answer: (B)

Phanerozoic Eon marks the interval from about 540 million years ago to today and is known for the abundance of fossils we see in rocks from this time. It includes three major eras—Paleozoic, Mesozoic, and Cenozoic—through which life diversified dramatically. The Cambrian is a period within the Paleozoic era, while Precambrian refers to the time before Phanerozoic, not to an era within it. The Archeozoic/Archean and Proterozoic eons are older eons that lie entirely before the Phanerozoic. Fossils isn’t an eon at all. So the eon spanning from about 540 million years ago to the present is Phanerozoic.

Phanerozoic Eon marks the interval from about 540 million years ago to today and is known for the abundance of fossils we see in rocks from this time. It includes three major eras—Paleozoic, Mesozoic, and Cenozoic—through which life diversified dramatically. The Cambrian is a period within the Paleozoic era, while Precambrian refers to the time before Phanerozoic, not to an era within it. The Archeozoic/Archean and Proterozoic eons are older eons that lie entirely before the Phanerozoic. Fossils isn’t an eon at all. So the eon spanning from about 540 million years ago to the present is Phanerozoic.