Concept explainers
To evaluate: The statement that the “Cambrian explosion actually consists of three explosions, not one.”
Concept introduction:
Cambrian explosion refers to the rapid diversification of animals that occurred 535-525 million years ago, during the Paleozoic era. Simple, soft bodied animals also called Ediacaran fauna inhabited the earth before the Cambrian explosion. There are various hypotheses that explain the Cambrian explosion.
According to one hypothesis, the appearance of a prey-predator relationship led to the Cambrian explosion. The predators in the Cambrian period acquired novel adaptations for predation. This led to natural selection of prey with hard bodies. The hard bodies helped them in defense from predators.
Another hypothesis emphasizes on the increase in atmospheric oxygen. The increase in atmospheric oxygen led to the evolution of animals with high
According to another hypothesis, the evolution of Hox genes (developmental genes) and microRNAs led to the evolution of animals with complex bodies. The evidences of first arthropods and chordates come from the rock strata of the Cambrian period.

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Chapter 32 Solutions
Campbell Biology
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