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        Thank you to Tracy Ford for beating me to the punch and
articulating what I think of comparing dinosaurs to mammals. A decade ago,
Bob Bakker created a new dinosaur paradigm, one where they were
hot-blooded, lively, energetic animals. Despite recent refutations of this
idea, I think that he got it right. Up to a point. Unfortunately, Bakker
went too far, and now the perception of dinosaurs as leaping, screaming,
running beasts (don't the dinosaurs in Bakker's world ever just stand
around, or walk?) comparable to modern-day mammals is the dominant one. But
while I do believe that dinosaurs were warm-blooded, they were NOT mammals.
To attribute mammalian behavior or mammalian physical traits to the
dinosaurs is a mistake. Dinosaur brains were not mammalian brains,
therefore they were not capable of mammalian behavior; dinosaur bodies were
not mammalian bodies, therefore they did not have the same type of physical
traits that mammals do.

        Rob Meyerson wrote:

> as they say, form follows function.  If features found in different
>animals   > are morphologically similar, then we can be pretty certain
>that those features > were used for the same purposes (the definition of
>"convergent evolution").     > Across the board, mammals with flat,
>blade-shaped > neural spines have some   > kind of hump structure, ranging
>from a camel's  fat-laiden hump, to a pig's   > muscle laiden hump (The
>only time we see a sail is when the spines are thin   > and needle-like).
>Since the spines of _Spinosaurus_ have this same            > morphology,
>then some kind of hump structure should have existed. As your     >
>favorite sage would say, "Size matters not."

        Rob, I think, negates his own argument: a camel's fat-laden hump
and a pig's muscle-laden hump (since when do pigs have humps?) are only
superficially similar externally; obviously, they do not perform the same
function. It is also completely erroneous to compare the neural spines of
_Spinosaurus_, _Ouranosaurus_, _Acrocanthosaurus_, or any other tall-spined
dinosaurs to mammals like pigs or camels. The neural spines in these
various, unrelated dinosaurs are tall all along the dorsal vertebrae; in
pigs and camels, the neural spines are are tall only over the shoulder area
(to serve as an area for muscle attachment) and have nothing to do with
humps. Pigs do not really display a noticeable *hump*, and while the
dromedary does, the hump is located midway down the back, over much shorter
spines, and is basically just a lump of fatty tissue, unsupported by
vertebrae. None of this applies to dinosaurs.

Brian Franczak (franczak@ntplx.net)