Re: Preview of new stegosaur plate paper

[don ohmes <d_ohmes@yahoo.com>]

To be honest, when I asked the question, it never
crossed my mind that antlers, horns, and ears would be
classified as display structures in the sense of
display as primary function, in part for the reasons
you mentioned. So I guess I should have written "pure
display". However, horns, ears, tusks, and antlers
aside, the birds alone satisfy me that the
proposition, even re-written, is probably incorrect.
Thanks.

Predation drives body size, which is enhanced by
thermoregulatory structures originally defensive in
nature... making stegosaur plates defensive any way
you look at it. Gets my vote.  Looking forward to
reading the paper.

Don

--- "Jaime A. Headden" <qilongia@yahoo.com> wrote:
> don ohmes (d_ohmes@yahoo.com) wrote:
> 
> <Intuitively, it seems to me that the relative size
> of display structures might
> scale negatively with body size. Does anyone have
> enough data from extant
> animals to comment on this?>
> 
>   I would only offer that the largest living land
> mammal (*Loxodonta*)
> currently has extremely large display/ventilation
> structures in its ears and
> tusks, and invests more energy in developing and
> maintaining these than the
> other, second largest land mammal (*Elephas*).
> However, larger mammoths are
> noted for having extremely large tusks but with tiny
> ears (possible tradeoff,
> but more likely climactic, in which time in the
> temperate SW USA region for the
> Columbian mammoth may not have allowed persistant
> size increase. All we can for
> positive measurements in ears are steppe mammoths,
> predecessors of the
> Columbian. So I am not sure.
> 
>   Large rhinos such as *Coelodonta* has larger nasal
> bosses for horn growth
> than living *Rhinoceros* or *Diceros*, and
> *Elasmotherium* tipped the rhino
> scales in apparent horn size (but it was also very
> northern and the horn's
> function -- display? -- is very debatable).
> 
>   The largest cervids have the largest antlers
> (*Alces*, *Megaloceros*), and
> *Rangifer* maintains them (as in *Loxodonta* tusks)
> in both sexes, but these
> again are more northernly climed animals.
> 
>   So there may be a positive value for display
> structure in size, even as many
> of these are agonistic in function and thus also
> correllate with size as use
> may require. Size of horns may also increase within
> a genus positively with
> size, as in *Ovis* where the largest sets of horns
> are most elaborated in the
> largest species, example being *Ovis canadensis* and
> related species group
> taxa. Purely display structures (as in peafowl
> *Pavo*) may still serve an
> alternate function, but these also appear in some of
> the largest of galliforms,
> as with turkeys (*Meleagris*, *Agriocharis*, etc.)
> and forest fowl *Gallus*.
> 
>   Cheers,
> 
> Jaime A. Headden
> 
>   Little steps are often the hardest to take.  We
> are too used to making leaps in the face of
> adversity, that a simple skip is so hard to do.  We
> should all learn to walk soft, walk small, see the
> world around us rather than zoom by it.
> 
> "Innocent, unbiased observation is a myth." --- P.B.
> Medawar (1969)
> 
> 
>               
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