What is the Phanerozoic eon?
Q: What is the Phanerozoic eon?
A: It is the current eon on the geologic timescale in which abundant animal life has existed.
Q: How long does the Phanerozoic eon cover?
A: It covers about 541 million years.
Q: When did hard-shelled animals first appear?
A: Hard-shelled animals first appeared during the Phanerozoic eon.
Q: What did scientists once think about the Cambrian period?
A: They thought that life began during the Cambrian period, which is the first period of the Phanerozoic eon.
Q: What is the Precambrian?
A: The Precambrian is the time before the Phanerozoic eon.
Q: How is the Precambrian period divided?
A: The Precambrian period is now divided into the Hadean, Archaean and Proterozoic eons.
Q: What is the significance of the Hadean, Archaean and Proterozoic eons?
A: They represent the time before the Phanerozoic eon, in which life was still emerging, and are collectively known as the Precambrian.
