Re: Preview of new stegosaur plate paper

[don ohmes <d_ohmes@yahoo.com>]

Sheesh. Replies below.
--- Mike Taylor <mike@miketaylor.org.uk> wrote:
> > Date: Wed, 18 May 2005 08:33:19 -0700 (PDT)
> > From: don ohmes <d_ohmes@yahoo.com>
> > 
> >>> Engineering and mass allocation considerations
> indicate that the
> >>> relative size of passive defense structures must
> scale negatively
> >>> with body size.
> >> 
> >> How so?
> > 
> > Muscle-to-mass ratios decrease with body size. 
> Assuming mass
> > specific power is equal, as mass increases, the
> relative muscle
> > power available to "tote that bale", or shield, or
> armor plate, or
> > shell, or .45 ammo, or anything with mass
> decreases. Big guys tote
> > bigger shields than small guys, but small guys can
> carry more shield
> > per kilo.
> 
> OK, but isn't that smaller proportion of muscle just
> a reflection of
> the fact that larger animals tend to be less
> athletic than smaller
> ones?

No, it is a reflection of the laws of physics. IT IS
NOT A MATTER OF PERSONAL PREFERENCE.

> >>> 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 don't have references to my fingertips, but I
> do recall that,
> >> surprisingly, this is often incorrect.  For
> example, the
> >> ludicrously big antlers of the recent deer
> _Megaloceros_ ("Irish
> >> Elk") scale _positively_ with body size, so that
> large specimens
> >> have proportionally larger antlers than smaller
> individuals.
> > 
> > Megaceleros' antlers may not have been even
> partially for
> > display... deer in rut are EXTREMELY aggressive. 
> What evidence do
> > you have that the (I grant you) apparently
> ridiculous size of irish
> > Elk antlers is a "display" trait?
> 
> Only that you'd just asserted that defence
> structures _must_ scale
> negatively.  If you're withdrawing that assertion,
> then, yes,
> _Megaloceras_ antlers (and the many other positively
> allometric
> structures in extant beasts) could be defensive.

I said PASSIVE defense structures. Antlers are
aggressive structures, not defensive, and are ACTIVE,
not passive. AND I DID NOT SAY "MUST'. And I will
"withdraw assertions" when someone makes a valid
point.

>  _/|_ 
>
___________________________________________________________________
> /o ) \/  Mike Taylor  <mike@miketaylor.org.uk> 
> http://www.miketaylor.org.uk
> )_v__/\  "If you don't know what your program is
> supposed to do, you'd
>        better not start writing it" -- Edsgar Dijkstra. 
> ("Though it's
>        a great way to find out" -- Mike Taylor.)
> 
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