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Re: Function Talks at Ostrom Symposium
Dwight, Jim, et al:
Just a thought regarding the ruptured diaphragm -
Perhaps other structures that might enable a creature with said rupture
to breathe with little difficulty COULD HAVE developed _prior_ to the
rupturing of the diaphragm. Just as today, a human born with an extra hole
in its heart (i.e. a blue baby) would die, more ancient ancestral creatures
had that hole and managed to survive quite well. For example, crocodiles
have a four chambered heart, yet can open a hole between 2 chambers to mix
the oxygenated blood with the depleted blood. The crocodile doesn't die,
and in fact gains some benefit from having the option to mix the
Could some of the more 'advanced' respiratory features of birds have
developed while retaining the diaphragm? And that later, the diaphragm
became a mere vestige - and finally, disappeared?
Of course, this is all SPECULATION on my part. Sometimes, the idea that
we humans can KNOW exactly what features developed first, and to what
degree - without full information!!! - is the epitome of arrogance.
Logical conclusions are one thing, but saying that X could not happen until
Y happens, based on the scantiest of information.....
[Please note - that last paragraph is an equal opportunity offender -
ALL OF US ARE GUILTY AT LEAST SOMETIME].
From: EctoDino@aol.com <EctoDino@aol.com>
To: Dwight.Stewart@VLSI.com <Dwight.Stewart@VLSI.com>; email@example.com
Date: Saturday, February 20, 1999 1:42 PM
Subject: Re: Function Talks at Ostrom Symposium
>In a message dated 2/20/99 1:32:53 AM Eastern Standard Time,
>1) > How certain is it that dinosaurs WERE diaphragm breathers? And
>2) > why would the transition
>> forms (IF dinosaurs were diaphragm breathers) be selected for a
>> diaphragmatic hernia?
>Hi Dwight, thanks for replying.
>1) Dinosaurs as diaphragm breathers is discussed in the 1/22 Science on p.
>2) What Ruben et al. meant is since birds are not diaphragm breathers a
>diaphragm breathing ancestor for birds would have to rupture its diaphragm
>gradually eliminate it and breath without one. However, you try breathing
>a ruptured diaphragm! Such a debilitating condition would immediately
>compromise the entire pulmonary ventilatory apparatus and seems unlikely to
>have been of any selective advantage.
>Hope that helps,