Indeed, so I will bring something up we discussed a long time ago - The Cambrian Explosion.
When we originally looked at the issue, I was questioning how it was possible for such a large "explosion" of various lifeforms to evolve so rapidly. From memory the conclusion we both came to was that since skeletal structures weren't around before this period, evidence of changes through evolution were lost. Hence there were changes but these weren't able to be shown until a more resilient structure (ie skeleton) was fossilized. In short, there was no change in the rate of evolution, just a distortion in the evidence of it.
I have a problem with this theory however (one that I read only a few weeks after the discussion). It seems odd that organisms that were that were relatively "soft" (without such complex structures) were found both before and during the Cambrian period, yet none of these transitional creatures have been. With this in mind, how do we explain this sudden explosion in life forms?
Here, is a link to many current theories surrounding the problem (courtesy of wikipedia
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