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Re: A whole lot of trouble....
this isn't incredibly dinosaur related, but...
On Tue, 29 Oct 1996, Stephen Throop wrote:
> This means a wing on a larger animal must maintain more pressure but
> can't be flapped as fast. That's why it would take a miracle for a big
> bug to fly in the manner of a housefly. It's also why the bumblebee is
> thought to be as large as possible for a flying animal of that design.
> Still, in the dinosaur days, there were flying bugs that were built like
> modern species except that they were much bigger, perhaps ten times.
> How could they possibly have flown?
I would argue, just by looking at modern ecosystems, that
vertebrate competition could be one of the major factors in preventing big
bugs. Wetas, for example, are enormously huge crickets, from New Zealand,
which was totally devoid of any rodents, though it does have geckos and
I've heard of big bugs from other islands, and perhaps this would
explain why coconut crabs (actually, like king crabs, they're hermit
crabs) get as big (3' across) as they do. The other big bugs are
pretty much all in the tropics- and the warmer an area, it would seem,
the larger the insects. This might have more to do with their
physiology- it seems to be true of ectothermic vertebrates as well,
considering that Purrusaurus, Megalania (Varanus ??),
Geochelone/Colossochelys, modern komodos, modern and extinct big
snakes, crocodiles, etc. etc. etc. are all from pretty warm areas. So
it may be that this is another factor working against large insects,
at least in many places in the world. Perhaps it has to do with
competition against endothermic vertebrates, not just vertebrates.
The strange thing is that this seems like it is reversed in the
water- king crab, spider crab, tanner crab, maine lobster, giant (1'
long) isopods and huge sea-spiders from cold waters, with relatively
few large arthropods from warmer waters- spiny lobster being the
biggest I can think of. There was a big die-off in Alaska king crab
populations about ten years ago, and it seems to coincide with warmer
waters that brought in predators like cod and halibut that stuffed
themselves with the young crab, so again, perhaps vertebrate
competition, although in this case our vertebrates might prefer warmer
> In scale, flying dinosaurs present bigger problems. One had a wingspan
> of 51 feet! In World War Two, an airplane that big would have needed
> two engines, 3,000 horsepower, and thousands of feet of runway.
Yes, but pterodactyls didn't have to carry thousand pound
bombloads, pilots, or machine guns, and they weren't made out of metal,