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Re: [Re: ... vs energy deficient gigantothermy (boo hiss)]

Just thought I'd respond before this got too old :)


"David Marjanovic" <david.marjanovic@gmx.at> wrote:
> Yesterday I wrote:
> > > [...]
> > > let's also remember that 140 million years of evolution has
> > > yet to produce a bird that even comes in at a tonne, much less a
> multitonne one;
> > > and birds are twice as metabolically active as mammals.
> >
> > And birds are K-strategists,
> Big ratites are, as HP GSP informed me, quite classic r-strategists. (I
> should have known that... :-] )
> The rest, however, has held up so far:
> > and they have IMHO not yet had a chance to grow
> > to gigantic sizes. The carnivorous ones had no gigantic prey         > >
available, and the herbivorous ones are seemingly too young (the      > >
biggest aepyornithids and moas were among the last).


I have no problem agreeing with that, but it does leave me with a bit of a
quandary; why is the lack of multitonne birds attributed to environmental
factors (e.g. no big game, died before their time) while the lack of
multitonne reptiles (excluding dinosaurs) is attributed to their physiology.
Did one ever stop to think that the reason why _M.prisca_ never got any bigger
was because it was large enough to be an effective predator of moas. I mean
oras are much smaller than _Megalania_ and yet they, theoretically_ were
taking down pigmy elephants.

Anyhoo, I'm in agreement with HP Matt Bonnan. There's more to meets the eye
here than simply physiology.


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