The Cambrian Explosion
The Earth was without diverse animal life for about four billion years until the Cambrian Explosion occurred. In almost a moment in geological time, complex life exploded upon the Earth. It was during this time that first life did appear including simple bacterial one-celled organisms and a few more complex multicellular species all not large enough to leave a visible fossil record. The Cambrian explosion happened about 543 million years ago. All of the animal phyla either evolved or first appears at this time. No matter where we look on Earth, there is no skeleton fossil records older than… Read More »