<span>The geologic time scale is divided into periods, which are then divided into epochs, which are further divided into ages. For example, the time of the dinosaurs lasted 3 periods (Triassic, Jurassic, Cretaceous), each period had 3 epochs (late, early, middle), and each age fit into one of those. Many epochs have more than 1 age associated with them.
As for the basis for differentiating the eras, I'm not so sure. The only one I can say for sure is the end of the Cretaceous, which is when the dinosaurs suddenly became extinct due to a meteor impact. I think the divisions are based on significant, global-scale events that changed the world.
Sorry its so long but that the answer i think >:) ur welcome
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The human race may survive through survival of the fittest. basically whoever has the biggest stick wins! The body also could adapt to the lack of water so you could preserve your bodily resources and manage them better. Or you could just change the environment to benefit yourself and mankind!
Eukaryotic cells contain several organelles it has: Mitochondria, chloroplasts, the endoplasmic reticulum, the golgi apparatus, and lysosomes. These organelles performs specific function critical to the cell's survival. <span />
