Re: Giant Giant Scorpions and Dino Breath

["Allan Edels" <Edels@email.msn.com>]

Concerning Oxygen levels in the Cretaceous:
    (I've posted some of this before)

A specific reference:
"Plate Techtonics and the Radiations/Extinctions of Dinosaurs, the Pele
Hypothesis" by Robert E. Sloan (Dept. of Geology and Geophysics, University
of Minnesota, Minneapolis, MN 55455),  from "DinoFest International:
Proceeding of a Symposium sponsored by Arizona State University"
pp.533-539.  This was originally presented at the DinoFest in 1996, and
published for the DinoFest in 1998 (March).

    The overall thrust of the paper is that changes in oxygen levels caused
an extinction of dinosaurs (64%)  by the early Cretaceous, with 100%
(excluding birds) at the end of the Cretaceous.

  Selected quotes from the paper:

    "1.  A high carbon dioxide generated extinction at the end of the
Jurassic and beginning of the Cretaceous with the introduction of large
amounts of carbon dioxide released from the mantle which triggered the onset
of the Cretaceous greenhouse and, 2. Falling oxygen levels, in the presence
of elevated carbon dioxide, cause respiratory stress in the exact time
interval when metabolic needs were increasing because of falling global
temperatures.  The second type may have been the ultimate cause for most of
the terminal Cretaceous extinction."


"*    Dinosaurs required 40 breaths to fully replace the air in their lungs.
 *    Mammals and Birds only require 7 breaths to completely replace the air
      in their lungs.
 *    Large Dinosaurs required elevated levels of O2 in the air to
      diversify."

Detail List of O2 levels (based on gases trapped in Amber):
    Barremian                           130 mya            28%
    Aptian                                  115 mya            29%
    Cenomanian                         95 mya            35%
    Turonian                                88 mya            33%
    Judith River Formation        75 mya            35%
    Basal Hell Creek                  70 mya            35%
    Hell Creek (Maastrictian)    68 mya            35%
    Top-most Hell Creek          65.2 mya          31%

    AFTER K/T Boundary         65 mya            29%

    Eocene                                 50 mya            16%
    Miocene                                20 mya            14%

    NOW                                     NOW               21%

Of course, some recent work (using new techniques) indicates that the O2
levels in amber may have been equal to current levels.

    Allan Edels

-----Original Message-----
From: Ben Creisler <bh480@scn.org>
To: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Friday, July 02, 1999 12:38 AM
Subject: RE: Giant Giant Scorpions and Dino Breath


>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?
>