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Re: Dinosaur heart found?



>In a message dated 4/20/2000 1:42:03 PM Pacific Daylight Time,
>Dinogeorge@aol.com writes:
>
>> High activity
>>  level follows from perfect blood aeration (and separation of low-pressure
>>  pulmonary circulation from high-pressure systemic circulation), but
>>  endothermy (mentioned in other posts) is not necessary for high activity
>>  level.
>
>I realize this is a dead horse that has been well and truly pulverized in the
>past, but how do we know this?  We don't *know* of any deterministic
>connection between perfect blood aeration and endothermy, but without any
>examples of a fully segregated circulatory system in a living ectotherm, we
>cannot prove that they are unrelated.
>
>Also (Greg Paul, I'm talking to you, wherever you are), I'd like to know what
>the sternal ribs and uncinate processes say about this animal's respiratory
>system.

Well, uncinates are present in tuataras (ossified, am I right?) and
cartilagenous in crocs. So they say nada, probably, by simply being there,
they are probably primitive for archosauromorpha+lepidosauromorpha. On the
other hand they are so big and platelike one wonders if they weren't up to
something weird. Similarly, (unossified) sternal ribs are present in
lizards, and people, but I've never heard of ossified sternal ribs in an
ornithopod so I assume these are unossified and again they're primitive as
far down as amniota or something.
        But if it isn't a heart- well, could it be a gizzard?