RE: Giant Giant Scorpions and Dino Breath

[bh480@scn.org (Ben Creisler)]

To: dinosaur@usc.edu
From: Ben Creisler (bh480@scn.org)
Subject: RE: Giant Scorpions and Dino Breath

In reply to a number of questions about insect size
and respiration I would recommend the following
article:
Graham, J.B., Dudley, R., Aguilar, N.M. & Gans, C. 1995
Implications of the late Paleozoic oxygen pulse for
physiology and evolution. Nature 375 11 May 1995:117-120.

The article discusses the hyperoxic atmosphere of the
Carboniferous as well as the size limits on modern insects and
other air-breathing arthropods because of respiration,
with numerous references. These invertebrates ultimately depend
on diffusion to oxygenate their tissues, even forms that can actively
ventilate their trachea, and thus face certain physiological limits on
body size.

An additional issue, of course, is the size limit on any animal with
an exoskeleton. Beyond a certain size range, the exoskeleton for a
land animal would need to be so heavy and strong that an arthropod
could not move or function--the dinosaur-size insects in the
movie version of Starship Troopers notwithstanding!

Two other recent articles that provide lists of references on the
topic of vertebrate life in different atmospheric conditions are:

Graham, J.B., Aquilar, N., Dudley, R. & Gans, C. 1996.
The late Paleozoic atmosphere and the ecological and
evolutionary physiology of tetrapods. In. Amniote Origins:
completing the transition to land. Editors: S. S. Sumida &
K.L.M. Martin. Academic Press 1996.

Hengst, R.A., Rigby, J.K., Landis & Sloan, R.L., 1997.
Biological consequences of Mesozoic atmospheres:
respiratory adaptations and functional range of Apatosaurus.
In: Cretaceous-Tertiary Mass Extinctions: biotic and
environmental changes. Eds: N. MacLeod & G. Keller.
W.W. Norton & Co. New York. 1997
(The authors conclude that Apatosaurus could have
done just fine in our modern air.)

Since this thread threatens to stray far off the topic of
dinosaurs, I'll throw in one more reference I came across
while researching the topic:

Morgan, R. 1994. Giant Peruvian dinosaur ant biology, husbandry
and display. American Zoo and Aquarium Association Annual
Conference Proceedings. 1994:321-326.

Giant Peruvian dinosaur ants? You mean E. O. Wilson and
Bob Bakker could give a joint presentation at a scientific gathering?