HELP INFO: DINOSAURS ARE WARM BLOODED

Antonio Guia guia at CC.UManitoba.CA
Mon Mar 28 22:01:54 EST 1994


On 28 Mar 1994, JOHN LAMPA wrote:
> Hi. I am trying to find some information concerning the argument that:
>              *          Dinosaurs are warm-blooded          *

The "are" would immediately disqualify the statement.

> If anyone has any convincing information regarding this topic or knows of 
> any material which could be useful for supporting and refuting the argument 
> please do not hesitate to Email me. Thank you.

I don't have any recent information, but i'll give you a summary of what i
can remember from the past.

First, dinosaurs were most similar to the modern day birds and to
crocodiles.  Their soft tissue was likely most similar to that of birds. 
Birds are warm blooded.   In fact, until just last year (and i'm not sure
if that paper in nature was the only one that disproved this) it was
thought that birds are in fact dinosaurs which were small enough that they
didn't have as high a requirement for food and hence survived the tragic
meteor strike that killed off all the large dinosaurs.  

Second, the upright posture seen in many of the dinosaurs is indicative of
a higher activity level, requiring some form of endogenous heat control.

Third, their bone structure indicates highly vascularized bones (Haversian
canal system similar to that of existing warm blooded animals, birds
included) which indicates that they grew rapidly and suggests that they
were warm-blooded.

Fourth, the ratio of predator to prey found in natur is about 25% in
cold-blooded predators, and about 1-2% in warm-blooded predators.  This is
because a warm-blooded predator needs about 10 times more prey to survive
than does a cold-blooded predator.  The fossil record comprizes of about
1-2% predators.

points against:

Birds have been shown to not be related as closely to dinosaurs (maybe).

Upright posture may have been just an adaptation to support the extra
weight.  (Earlier dinosaurs were much smaller but already had the upright
posture.)

The Haversian canal system may have been merely due to a requirement for a
fast rate of growth.  (This is possible, but there was also the brooding
requirements where the eggs were temperature sensitive as to whether it
would come out male of female.  this suggests that they must have been
warm-blooded otherwise if a few of those millions of years were too hot or
too cold then there'd only be males or only females that year, and that
would upset their survival and allow warm-blooded animals to predominate)

The distribution of predators to herbivores in the fossil record may be
only related to where most of these dinosaurs were dying.  Herbivores
would spend more time around swamps where their bones would more likely be
preserved, carnivores may have travelled from swamp to swamp and if their
journey was too long and without food then they'd die out in the open and
their bones would deteriorate.   (But footprints records also show the 1-2%
ratio.)






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