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Re: mammal mystery




On Wed, 19 Feb 1997, Ronald Orenstein wrote:
> A number of rails ARE flightless, yes.  These include small-island forms
> but also some fairly good-sized birds on islands like New Guinea and
> Tasmania that certainly have predators capable of eating them. 

"...some fairly good-sized birds on islands like New Guinea and
Tasmania..."  This is a relative dearth of flightless bipeds.  What do you
suppose the ratio of quadrupedal lizards and mammals and snakes and flying
birds is to flightless birds.  Very small.  My point is that species of
this body plan are not very competitive in close cover.  I still think I'm
right about that.  I think 2 legs is inefficient for running through
tangled hoops.  As you have noted I have little knowledge about rails.
The five species I have read about all seem to inhabit grassy environments
which are relatively free of horizontal encumberances.  Tell me two
things: 1. How does a rail move through a hoop at full speed, like a
spear? Try not to ridicule this point.  I honestly can't imagine such a
creature out running a, say, rat in a close hooped environment
        2. If bipedalism was no impediment to dinosaurs in close-cover,
why do you think they were excluded?  (I believe we do see mammal
replacement at least in this niche, no?)
 
> In a tangled thicket wings are a lousy means of escape - much better to
> creep away on foot, as most terrestrial birds of such habitats do - and
> they are damned good at it.  I really think you should brush up on the
> natural history of such birds before making such pronouncements - what you
> say about bird locomotion is simply not true.

I appreciate your knowledge a great deal, and a great deal more than your
manners.  Mine is a reasonable hypothesis whether or not you like it.
Rails are like Doctor Johnson's dog standing on its hind legs two legs:
they are amazing not because they move around in close cover well, but
because they can do it at all!