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Re: respiratory turbinates, mesazoic birds, pterosaurs, mesazoic



On Mon, 16 Sep 1996 gpb6845@msu.oscs.montana.edu wrote:

> Has anyone done any studies on the RTs in Mesazoic almost-Birds like
> _Archaeopteryx_ and _Mononykus_ (I'm not saying that they're closely
> related, just that they have been tauted as _undeniably_ being birds,
> but probably aren't quite)?

        I can't really think of what else Archaeopteryx could be. Since 
it doesn't appear to be too far removed from Confuciusornis, it seems it 
would almost certainly have had insulatory feathers like its relatives, 
as well, so it would almost certainly be warm-blooded.  

>  How about definate birds like _Confusciusornis_ (sp),
> _Iberomesornis_, and _Ambiortus_?  Heck, why not even try
> _Hesperornis_ and _Icthiornis_ for that matter.  And as long as
> we're searching for RT's let's look for them in Pterosaurs too.  And
> in early mammals, let's see when mammals actually developed RTs.
> Until this is done, I think that Ruben and his flock (ie the about
> 10,000 co-authors) might be jumping to some conclusions that aren't
> based on the strongest of evidence

        I seem to recall a therapsid that showed respiratory turbinates 
from a couple years back. 

        On the subject of asteroid impacts- there has been talk from time 
to time of multiple impacts. It seems to me that if there were other 
impacts, they would most likely (70% of the time) hit ocean, not land. If 
so, would we have remains of them (iridium, tidal wave deposits, etc.) 
and would they have any effect on the environment (what happens when you 
vaporize countless tons of seawater- besides, of course, rain?)
        The other bit is on the bone spike. Consider that the
preservation rate for dinosaurs of various times and places varies
enormously between "very, very low" and "almost nothing". Consider
that dinosaurs are dying all the time, and if say, 5% of the dinosaur
population dies in any given year, then if we have 100% mortality over
the course of one year we have twenty times as many bones to be
preserved. Of course, if your preservation rate is almost zero, 20 x
~0 = ~0. I guess what I'm asking is, should we really expect a bone
spike? Is preservation that good, and if it exists, would we even see
it?
        Animals die all the time, and over 220 million years there have 
probably been hundreds of thousands of dinosaur species,  which 
could have had thousands, millions or trillions of individuals over their 
lifetimes (in case you think I exaggerate, consider the Wilson's petrel 
or passenger pigeon) and when you think about that and then think about 
how many we have to show for it all after a couple centuries of 
paleontology- well, you know, it seems to me the extinction of every 
dinosaur on earth alive during one single point in time is kind of a drop 
in the bucket. And what if they didn't all die at once, but over ten, a 
hundred, a thousand years?