Re: Coping w/ the rule; was metabolic rate [...]

[don ohmes <d_ohmes@yahoo.com>]

Agreed, there are many exceptions. Hence the use of "usually". 

One point; if two generic men are being chased by a large lion, and one is 1.5 
m  tall, and the other is 2m tall, it might be wise to bet on the taller guy, 
all other things being equal; he can probably run faster, and may even have 
some intimidation factor. Plus he can knock the little guy down, in hope that 
the lion will be distracted, and opt to forgo 'upsizing' ... }: D. 

I use the above cartoon to clarify the sense in which I use the concept of 
"size aids in avoiding predation"; that's as opposed to a "simply being too big 
for the predator to handle" scenario I think you are using. Note also that the 
tall guy probably has the advantage in some other areas of life, and that 
advantages are additive, in the probability sense. 

If memory serves, the hypothesis that being in the upper end of the size 
variance of your cohort increases reproductive success, across taxa (fruitflies 
to mammals), has support in the lit., so references are available (again, if 
memory serves).  It would cost me a full day, no small effort, and probably 40$ 
out-of-pocket (minimum) to do a proper job of digging them up, though. Perhaps 
someone w/ online access could weigh in?

To reiterate my central point; IF a "statistical appearance" of Cope's Rule is 
indeed found in the fossil record, why would we look any further than 
simplistic "big is usually good" and "prototypes (ie, basal organisms) usually 
have room to improve" mechanisms as cause?

Don 

----- Original Message ----
From: john bois <jbois@verizon.net>
To: dinosaur@usc.edu
Sent: Sunday, October 14, 2007 9:05:13 AM
Subject: Re: Coping w/ the rule; was metabolic rate [...]


Don Ohmes said:
> Further, here in the 'Newtonian zone', sometimes it is good to be
 small.
> However, it can be effectively argued that whether engaged in
 competition 
> for resources, avoiding predation, or efficient utilization of
 resources 
> obtained, it is _usually_
> advantageous to be bigger than the competition, within the limits
 inherent 
> to your particular design
> and lifestyle.

But so many exceptions to this: extant dinosaurs avoid predation by
 being 
small (i.e., for hiding and flying); some mammals avoid predation by
 being 
fast and not big, some avoid it by being small in order to hide--most
 do not 
use size to avoid it; lizards and snakes remain small to take advantage
 of 
their body plan (i.e., it gives them a way to hide); and then there are
 the 
arthropods, molluscs, echinoderms, and annelids, etc., etc.--all of
 whom may 
have other limits on size but who nevertheless employ means other than
 brute 
strength to avoid being eaten.