Wednesday, April 15, 2009
The Cambrian Explosion
By the end of the Precambrian period (4.5billion- 543 million years ago) the fossil record consisted mainly of microscopic organisms (domain archaea, domain bacteria, kingdom protista), cnidarians, and chitons ( soft-bodied mollusks). However, most of the major groups of animal phyla appear in the fossil record only 20 million years after the Ediacaran, in the early Cambrian period. This rapid diversification of animals in a short period of geologic time is called the Cambrian explosion. Use your knowledge of evolution, specifically "evo-devo", to explain the possible environmental or genetic causes of this remarkable period of diversification.
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I believe its the simple fact that organisms finally became "complex" enough where they could diversify at a more rapid pace into more intersting organisms. Using your previous thread Vik, I think this is around the time cells finally developed complex structures like a flagella, and now more mutations were beginning to occur to a larger genetic code, meaning more diversity. Basically this was in a sense "the dawn of civilization" in biological terms where organisms were now able to forge out paths because they had enough "tools (DNA) " to do it with.
ReplyDeleteI also think that after a point it was no longer favorable for an organism to grow even more complex so the period of diversification began to slow down as the "better" organisms which had adapted to the land began to just steadily live. Also, around this time the geography of the earth was beginning to become more "life-like" allowing for more complex organisms begin to form habitats. And also, you can't count out luck. Alot of evolution has to do with luck, and even so you can't measure luck, maybe this period was just one big general lucky streak for evolution as many different organisms were able to get a favorable trait over an extended general time =D. Or, say more lucky than the other 4 billion years before that point.