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re: crests and pronounciation



>From: "Paleontology Columbus College, Georgia" <@lepomis.psych.upenn.edu,@ > 
 > On crest coloration in hadrosaurs:
 >   I have no problem assuming that, say, dilophosaur crests or, say, allosaur
 > suprorbital crests were colored, as display items should likely be.  However,
 > hadrosaur skull features were elaborations of nasal structures, which 
 > Dodson, an
 > and many others argue functioned as trumpets/signal devices.  There is no
 > reason these were for visual display and they were unlikely to have been
 > visually colored.

I would tend to disagree with this, as I see no reason they could
not be both sounding devices and visual displays. One of the
reasons I lean towards an ancillary display function is that
they have such various and curious shapes.  This sort of variation
is unneeded for a purely auditory function.  Simply changing the
length and internal branching of the air passages would be all
that was really needed.

A good example of this is the Corythosaurus/Lambeosaurus cluster
of three species.  In this group, one species has a backward
pointing spike on the crest that does *not* contain any air
passages (the type species of Lambeosaurus).  And the difference
in orientation of the crest between the species is far beyond
what is required by the differences in length of the sounding
passages.

And I find the shape of the crest in Parasaurolophus to be
too prominant and too exposed for a purely auditory device.
[It could easily have been bunched up like Hypacrosaurus, or
laid down along the skull, rather than erect as it is].

swf@elsegundoca.ncr.com         sarima@netcom.com

The peace of God be with you.