31 August, 2005

The Prehistoric Mass Extinction

The BBC had an article on a mass extinction in prehistoric times. It isn't talking about the demise of the dinosaurs, but instead a much earlier die-off 250million years ago. Back 250million years ago, there were animals not unlike now: Insects, arachnids, crustaceans, amphibians and reptiles. It also had trilobites which were the species of the time (more information here) and are extinct now (as far as I know).

The difference between us and them is that they were the first of their kind. Earth had never before known the large herbivores and carnivores of this time period, and as a result, it was highly unstable. The Earth was also much more active then, and thanks to a ton of volcanoes erupting over a few hundreds of thousands of years the C02 levels rose to inhospitable conditions of 10% more then it currently is. As a result, 90% of the wildlife died out. However it is possible that the trilobites actually died out due to the appearance of sharks and other fish. In fact, it's possible that the rise in C02 isn't truly the cause for the mass extinction. Merely because a computer model says it could happen, doesn't mean it did (or even really could). However if it did happen, it's truly interesting.

Much like the die out of the dinosaurs allowed mammals to become dominant, the massive die-out of the Permian period allowed the reptiles to rise and fill the new empty niches, the reptiles evolving into the dinosaurs we all know about.

It's amazing to think that the Earth has known these three distinct types of life, and that each demise resulted in the rise of another life-form. It makes you wonder, which life form will become dominant once us mammals die out (and based on the past, it's only a matter of time for us).


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