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Re: How large insects may have come about



 The leading theory is that ancient bugs got big because they
 benefited from a surplus of oxygen in Earth's atmosphere. But a new
 study suggests it's possible to get too much of a good thing: Young
 insects had to grow larger to avoid oxygen poisoning.

Were _all_ insects that large in those times???

 This may be because insect larvae typically absorb oxygen directly
 through their skin, so they have little or no control over exactly
 how much of the gas they take in. [...] One way to decrease the risk of
 oxygen toxicity would have been to grow bigger, since large larvae
 would absorb lower percentages of the gas, relative to their body
 sizes, than small larvae.

Another would be to grow a thicker cuticle...