Originally Posted by Idaho_Shooter
Originally Posted by WYcoyote
[Linked Image from i.postimg.cc]
Wow, I like that. There is a lot of data summed up there in an accessible format.
Even though it doesn't indicated it in that graphic, the oceans were teaming with life prior to the Cambrian. They just lacked hard parts that fossilize. That was a later development, when armor and such became necessary.