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Re: Hot-blooded dinos



 From: pwillis@ozemail.com.au (Paul Willis)
 > Crocs and turtles are also known from the Victorian sites. While both also
 > have known abilities for hybernation, or at least a torpid state, neither
 > use this as a stratergy to survive in arctic conditions.

We are talking more cool temperate/maritime, by modern standards.
No hard freezes, just persistant frost, and only in the winter.

It is true that the crocs would have had to have a different life
style that modern ones to deal with that - but winter torpor *could*
accomplish what is needed.

[The American alligator uses torpor to survive the *dry* season,
not the cold season, but the principle is similar].

 > it could not have been as severe as similar latitudes today
 > and, the non-dinosaurian component of the fauna suggest a climate similar
 > to the Carolinas. However, according to Rich and Vickers-Rich, the 18O/16O
 > ratios indicate mean a paleotemp of between +5 degrees C and -6 degrees C.
 > This would seem much too cold for crocs and turtles so there has to be
 > something wrong here (either it is the 18O/16O palaeotemp data or
 > Cretaceous crocs and turtles had a very different biology to their modern
 > counteparts).

The problem is that is other similar situations (aka Alaskan North Slope),
the fossil *plant* data correspond to the oxygen isotope temperatures.

Also, all existing climatic simulations generate temperatures of about
that level for the arctic of the time.

One thing to keep in mind is that the annual variability was also
pretty low, so the winter average may have been warmer than comparably
cold climates today.

Also, there is not that much difference between the Carolinas and
New Jersey  which is close to the climate suggested by the isotope
and tree data.

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.