Re: Dinosaurian Class (was: DROMAEOSAURS AND OVIRAPTOROSAURS ....)

[bchoo@cyllene.uwa.edu.au (Brian Choo)]

David Hill wrote
>I think the difference of endothermy and ectothermy should not be excluded.
>        The basic rules that you are using have holes in them.  Lizards
>look alot like salamanders so that means reptiles are amphibians! Early
>amphibians look like lungfish, therefore amphibians are fish.  You see, it
>just keeps going!  We need stricter guidelines.
>
>Sincerely
>NDH
>

How does one draw the line between ecto/endothermy in the fossil record?
Ideas on extinct physiologies are based on wonderful past-times like
functional anatomy and phylogenetic comparison where, to put it bluntly,
different people see different things. One cannot directly prove that
fossil organism X was actively homeothermic while fossil organism Y was
not. Thus there is no way of ever truly knowing if we really are
classifying endothermic and ectothermic animals together...and if
physiology ever became a REAL criterion for classification we would be at
each others' throats till eternity.

Finally, should endothermic fish such as lamnid sharks be in their own classes?


Cheers
Brian Choo