Re: Hot-blooded dinos

[jdharris@csn.net (Jerry D. Harris)]

>> -Upright gait:
>I seem to remember a lizard that can run for some distance on it's
>hind feet.

        A few can, yes...but they don't _live_ that way.  Even
quadrupedally, lizards can only run for comparatively short distances
before they exhaust their energy reserves.  That's a big portion of the
advantage of endothermy:  you can keep producing your own energy (as long
as your food holds out!)

>> -Predator-prey ratios: In the Ghost Ranch Quarry there are a 90% of
>>predators (I don't know the exact numb
>> er, but it would be nearly of that one), the same in the Morrison
>>Formation and
>>  in some others.
>I suppose if you happen to uncover a group of fossil baboons, or even lions, in
>their living quarters, you would get a very high value of the
>predator:prey ratio. Even if you have a death assemblage in situ, you
>will not be dealing with a living community when dealing with animals
>that could travel great distances.  You would probably have to
>uncover a single stratigraphical level the size of the Serengeti to have
>anything close to a reliable community structure for dinosaurs.

        The Ghost Ranch site is only a tiny fraction of the Chinle
Formation, as is the Cleveland-Lloyd Quarry (the apparent allosaur trap to
which I think you're referring) for the Morrison.  Don't make the mistake
of thinking that these productive quarries are representative of the
formations as a whole!  The Morrison's extent certainly has the Serengeti
beat in area (I think), and overall produces far more herbivores than
carnivores.  The Chinle does, too, but in the Triassic, we're not dealing
with only dinosaurs (lots o' "thecodonts").



Jerry D. Harris
Denver Museum of Natural History
2001 Colorado Blvd.
Denver, CO  80205
(303) 370-6403
Internet:  jdharris@teal.csn.net
CompuServe:  73132,3372

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