Bruce Moomaw wrote:
>
> While I didn't know that the huge dragonflies held on into the early
> Mesozoic, Clements' explanation has a big problem: why didn't the equally
> huge crawling bugs of the Carboniferous Era hold on? They didn't have the
> clumsy-flight disadvantage of those huge dragonflies -- there's no obvious
> competitive-evolutionary reason why we don't still have two-foot cockroaches
> and 6-foot millipedes around. It seems likely that the decline of the
> oxygen level in the early Mesozoic was indeed the key factor in nudging
> these horror-movie refugees into extinction.
>
> Of course, one qualification: there are still a few giant gadflies around.
> Witness Clements.
>
> Bruce Moomaw
You're taking me way back into biomechanical studies i thought i forgot decades
ago; but there are disadvantages to being a large hard shelled bug of any kind.
One of the bigger is respiration; which is why the O2 rich periods of the
Palezoic suited our not-so-little frees to a t (or more precisely: 02); but in
the absence of competition capable of perhaps literally stomping these critters
out of existance, big bugs would still be around... qv, the weta in NZ; which i
think is one of the biggest land arthropods surviving; & which did survive in
the highly anomalous New Zealand paleoenvironment.
All the best,
Robert Clements <[EMAIL PROTECTED]>
==
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