[Odonata-l] ancient dragons and oxygen

Thu Jul 10 23:33:03 PDT 2008

There's a leap of logic going on here. The fact that higher levels of oxygen
were necessary to support larger insects does not mean that supplying larger
levels of oxygen would somehow cause current insects to grow larger. The
higher levels of oxygen were not the reason for the gigantism, they were
merely a necessary precondition. The reason for the evolution of larger
dragons was, one might speculate, the absence of birds and pterodonts;
meaning that there was an ecological niche for larger aerial preditors
available for the dragons to fill.

A relavent paper is available here
http://jeb.biologists.org/cgi/reprint/201/8/1043.pdf  (ATMOSPHERIC OXYGEN,
GIANT PALEOZOIC INSECTS AND THE EVOLUTION OF AERIAL LOCOMOTOR PERFORMANCE)

Andy Brazil

> I and my grandsons recently attended the newly opened Audubon Insectarium,
> in New Orleans Louisiana.
>
>
>
> Near the beginning of the exhibit they have a replica of an ancient giant,
> (about 30 inch wingspan) dragonfly / mosquito hawk as it is more commonly
> called here.
>
>
>
> The information accompanying it asserts that the creature, (then and now)
> has relatively inefficient body structures for taking in atmospheric
gasses,
> meaning oxygen.
>
>
>
> The supposed reason for the gigantism is that ancient atmospheric levels
of
> oxygen concentration were much higher than today's levels, allowing the
> inefficient respiration system to take in enough oxygen to support large
> size.
>
>
>
> The theory continues that today's much lower oxygen concentrations cannot
> support such growth.
>
>
>
> I have my doubts about that concept.
>
>
>
>
>
> I have two questions for which I am seeking authoritative sources of
> information:
>
>
>
> 1. Can these creatures be generationally raised in captivity?
>
>
>
> 2. In an effort to test the question of the oxygen concentration effect on
> growth, has anyone ever tried to raise these creatures in captivity to
study
> the effects of an increased, (artificially) oxygen level concentration
> approximating supposed ancient levels?
>
>
>
> If you can and will answer these questions that would be good. Barring
that,
> if you could provide some ideas for other likely sources of such
> information, that also would be good.
>
>
>
>
>
> My name is Mr. Terry Teague. tteagnola at aol.com
>
>
>
>
>
> Thank you for any information you can provide.
>
>
>
>
>
>   _____
>
> Get the scoop on last night's hottest shows and the live music scene in
your
> area - Check out <http://www.tourtracker.com?NCID=aolmus00050000000112>
> TourTracker.com!
>
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> ------------------------------
>
> Message: 2
> Date: Thu, 10 Jul 2008 23:38:24 -0400
> From: "Nick and Ailsa Donnelly" <tdonelly at binghamton.edu>
> Subject: Re: [Odonata-l] help with info
> To: <iodonata at bellsouth.net>, <TTEAGNOLA at aol.com>
> Cc: 'Odonata-l discussion' <odonata-l at listhost.ups.edu>
> Message-ID: <005301c8e307$930edc40$6600a8c0 at AILSA>
> Content-Type: text/plain; charset="us-ascii"
>
> I believe oxygen could not be the correct answer.  Numerous scaling
> observations relating body mass to oxygen consumption shows that the
modest
> increase in oxygen that possibly existed during the Permian (when all the
> Caroniferous coal beds were buried and not yet exhumed) would have only
> increased size by a rather small amount - certainly not 4X linear
dimensions
> (which is 64X body mass).
>
> More probably the question has always been asked incorrectly.  The
question
> assumes that the size of modern dragonfies is limited by oxygen partial
> pressure.  I believe they are limited by predation pressure combined with
> the increased demands for food to support the life style of nearly
constant
> flying.  During the Permian predators were few, and, until the rise of the
> giant amphibians in the late Permian, would not have limited anything.
And
> we don't know the dragonfly's life style.  Did they fly only briefly and
> then have to rest for a while to recover?  I guess we should regard the
> observation of large Permian dragonflies as evidence for extremely low
> predation pressure and sufficient available food (other insects).
>
> I also seem to recall that metabolic experiments involving grasshoppers
> showed that they had more than sufficient capacity for oxidizing muscle
> metabolites during  the exercise of tethered flight.
>
> Once efficient predators evolved, there was no place for large insects and
> they had to abandon large size - where they remain to this day.  By the
way,
> there were also large insects in other orders, such as orthopteroids.
There
> were also lots of small insects in the Permian.
>
> Nick Donnelly
>
>   _____
>
> From: odonata-l-bounces at listhost.ups.edu
> [mailto:odonata-l-bounces at listhost.ups.edu] On Behalf Of
> iodonata at bellsouth.net
> Sent: Thursday, July 10, 2008 8:32 PM
> To: TTEAGNOLA at aol.com
> Cc: Odonata-l discussion
> Subject: [Odonata-l] help with info
>
>
>
> Hi group:
>
>
>
> The second question opens up some discussion which has not been covered
here
> as far as I can remember.
>
>
>
> See if you can help
>
>
>
> Thanks.
>
>
>
> Bill Mauffray
>
> International Odonata Research Institute
>
> PO Box 147100
>
> Gainesville FL 32614-7100
>
> 352-219-3141 cell
>
> iodonata at bellsouth.net
>
> http://www.iodonata.net
>
>
>
>   _____
>
> From: TTEAGNOLA at aol.com [mailto:TTEAGNOLA at aol.com]
> Sent: Wednesday, July 09, 2008 7:39 PM
> To: iodonata at bellsouth.net
> Cc: TTEAGNOLA at aol.com
> Subject: Info please
>
>
>
>
>
>
>
> I got your contact information from the Odonata Information Network web
> site.
>
>
>
> http://bellsouthpwp.net/b/i/billmauffray/main.html
>
>
>
>
>
> I and my grandsons recently attended the newly opened Audubon Insectarium,
> in New Orleans Louisiana.
>
>
>
> Near the beginning of the exhibit they have a replica of an ancient giant,
> (about 30 inch wingspan) dragonfly / mosquito hawk as it is more commonly
> called here.
>
>
>
> The information accompanying it asserts that the creature, (then and now)
> has relatively inefficient body structures for taking in atmospheric
gasses,
> meaning oxygen.
>
>
>
> The supposed reason for the gigantism is that ancient atmospheric levels
of
> oxygen concentration were much higher than today's levels, allowing the
> inefficient respiration system to take in enough oxygen to support large
> size.
>
>
>
> The theory continues that today's much lower oxygen concentrations cannot
> support such growth.
>
>
>
> I have my doubts about that concept.
>
>
>
>
>
> I have two questions for which I am seeking authoritative sources of
> information:
>
>
>
> 1. Can these creatures be generationally raised in captivity?
>
>
>
> 2. In an effort to test the question of the oxygen concentration effect on
> growth, has anyone ever tried to raise these creatures in captivity to
study
> the effects of an increased, (artificially) oxygen level concentration
> approximating supposed ancient levels?
>
>
>
> If you can and will answer these questions that would be good. Barring
that,
> if you could provide some ideas for other likely sources of such
> information, that also would be good.
>
>
>
>
>
> My name is Mr. Terry Teague. tteagnola at aol.com
>
>
>
>
>
> Thank you for any information you can provide.
>
>
>
>
>
>   _____
>
> Get the scoop on last night's hottest shows and the live music scene in
your
> area - Check  <http://www.tourtracker.com?NCID=aolmus00050000000112> out
> TourTracker.com!
>
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>
> End of Odonata-l Digest, Vol 54, Issue 3
> ****************************************
>