LIFE SCIENCE

Detailed explanation-1: -The Cretaceous is the longest period of the Phanerozoic Eon. Spanning 79 million years, it represents more time than has elapsed since the extinction of the dinosaurs, which occurred at the end of the period.

Detailed explanation-2: -The Precambrian encompasses the Archean and Proterozoic eons, which are formal geologic intervals that lasted from 4 billion to about 541 million years ago, and the Hadean Eon, which is an informal interval spanning from 4.6 billion to 4 billion years ago.

Detailed explanation-3: -The Precambrian was the “Age of Early Life.” During the Precambrian, continents formed and our modern atmosphere developed, while early life evolved and flourished. Soft-bodied creatures like worms and jellyfish lived in the world’s oceans, but the land remained barren.

Detailed explanation-4: -The Precambrian Era comprises all of geologic time prior to 600 million years ago. The Precambrian was originally defined as the era that predated the emergence of life in the Cambrian Period.