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Science Forum Index » Bio Evolution Forum » Trilobite Eyes and the Cambrian Explosion...
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 Posted: Fri Aug 01, 2008 7:22 am |
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Guest
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I just read of an interesting theory that the Cambrian Explosion
was touched off by the evolution of eyes in a prototrilobite. The new
animals, with imaging optics, became such efficient predators that
animals had to develop both hard parts and eyes of their own to
successfully ward them off. So the development of eyes in arthropods
generated new types of predation that caused an increase in animal
diversification.
The fellow who developed this theory points out that trilobites
were the among both the first animals to have hard partsand the first
animals to show eyes, early in the Cambrian. Other phyla didn't leave
fossils of eyes until much later, near the end of the Ordivician and
maybe even during the Silurian. Arthropods other than trilobites
develop eyes, although much later than trilobites. So trilobites eyes
touched off the explosion in diversity at the beginning of the
Cambrian.
However, I have a problem with this theory. Can any help me with
this?
As far as I know, trilobites do not show signs of being efficient
predators. At least not of animals comparable in size, the ones
trilobites could most likely see. Why would the development of
trilobite eyes increase the magnitude of large animal predation, when
the trilobites never developed the necessary armament to become large-
animal predators?
There may be a problem in defining predation as large animal
predation. However, I don't see how eyes would have been very useful
for small animal predation.
Could eyes be useful for grazers? Maybe there were trilobites who,
with eyes, could graze on plant life. But then why should there be
such an increase in anmal diversification?
What would eyesight in trilobites have made such a difference. |
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