What is the Cambrian Explosion?
Q: What is the Cambrian Explosion?
A: The Cambrian Explosion is when many animal phyla first appeared in the fossil record. It happened 541 million years ago (mya).
Q: How long did it take for most of the phyla we know today to exist?
A: Over the following 70 or 80 million years, the rate of evolution seemed to accelerate and by the end of the Cambrian, most phyla we know today existed.
Q: When was it first noted that fossils were appearing rapidly in 'primordial strata'?
A: It was first noted as early as the mid 19th century.
Q: Who saw this rapid appearance of fossils as an objection to their theory?
A: Charles Darwin saw this rapid appearance of fossils in 'primordial strata' as one of the main objections that could be made against his theory of evolution by natural selection.
Q: What type of organisms existed before 580 mya?
A: Before about 580 mya, it seems that most organisms were simple. They were made of individual cells, occasionally organized into colonies.
Q: Was there any evidence that animals had evolved before they appeared in fossil records?
A: Probably most had evolved before then, but that was their first appearance as fossils.
