Re: Cursorial adaptations (was T.rex and elephants)

[Chris Campbell <sankarah@ou.edu>]

Pieter.Depuydt@rug.ac.be wrote:
> 
> Dann wrote:
> > An interesting point, although the problem with many of
> > the counter-balancing crest theories is that you often get closely
> > related species with much smaller crests. The crest of Pteranodon
> > sternbergi is much larger than P.ingens, and the closely related
> > Nyctosaurus has barely a crest to speak of. The much larger
> > Quezelcoatlus has an even smaller crest.
> >       I would argue that styracosaurus had a much heavier
> > and more cumbersome frill in life than its female counterparts.
> > Similarly, is there enough difference between the front ends of the
> > skulls of torosaurus and triceratops to suggest that torosaurus
> > needed the counter-balance? With such cases of overkill it would
> > seem that display formed a significant part of the function of the
> > frills.
> 
> Very plausible indeed. At least in Protoceratops, there is some
> evidence of sexual dimorphism, with males having more pronounced and
> rather 'upturned' frills.
> Ceratopian frills also might have been quite convenient to get rid of
> excess body heat in those fairly compact animals living in those hot
> Late Cretaceous times. (I remember  a Nature publication from the
> 'post Bakker-Ostrom' late eighties (have to look up the reference,
> don't remember the author) in which various dinosaur novelties were
> reviewed as having a thermoregulatory (in casu cooling) function).

Looking at the orientation of the frills, though, I think they'd be more
effective at absorbing heat than radiating it.  Something like Stegosaur
plates would be ideal for dumping heat, but a frill?  I suppose it might
be useful if the animal stuck to heavily shaded areas, but this strikes
me as a secondary or tertiary function at best.

Chris