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Re: Orenstein's pedestrian arguments.




> 1. Accounts I have read of rails say that they fly when flushed from
> cover.  They only seem to do this as a last resort.  But, as a last
> resort, it is probably adaptive.  Many creatures have facilities they
> don't use as part of their "daily activity".  I think Orenstein is taking
> a simplistic view of rail behavior here.  The ability to cope in
> rare emergencies is as critical an adaptation as routine behavior.
> Clearly, rail species that live where there are mammals and snakes _need_
> to be able to fly.

     Wait a minute; one way to argue it is that rails fly because they
are not as good at escaping through the underbrush as mammals, so they
need to fly to make up for the inadequacy.  Another way to look at it is
that rails and mammals are both equally good at escaping through the
undergrowth, but both have chance at being caught no matter how
slinky they are, and flying is a useful backup that the rail has that the
mammal doesn't.

> Here is my preconceived notion: dinosaurs of the late cretaceous got
> bigger.  There was none smaller than a chicken.  There must have been a
> reason for this.  I think this quote from John McLoughlin's _Synapsida_
> can enlighten: "Represented by the rodent-like multituberculates,
> marsupials, forest-bottom insectivores, and tree-dwelling primates, these
> furry creatures shared with a growing number of birds the art of being
> small and living in micro-habitats in which larger animals could have no
> interest." 

     So you just may have some sort of case that mammals exploited a niche
that dinosaurs could not, either due to competition or some anatomical
limitation on the dinosaur's part. It may even be true that the
dinosaur's inability to get really small may have been related to thier
inability to survive the K-T extinction; smaller animals can be more
numerous, and if the K-T extinction involved some sort of genocidal
catastrophie, sheer numbers of individuals may have been an important
factor for survival.  This may well have also been important to the
survival of birds.
     However, your idea that "non-stealthy" egg was laying instrumental to
the dinosaurs being driven to extinction by infanitcide at the hands of
the mammals is still unsupported. As already noted, the K-T extinction
was a global and taxonomically widespread phenomena that is difficult
to explain with the evolution of a geographically confined egg-eating
mammal species.  Add to this the global success of the dinosaurs
during the span of the Mesozoic while coexisting with small, potentially
egg eating mammals, and the idea of mammals harassing dinosaurs to
extinction becomes totally unsupported. You have correctly pointed out
that "stealthy" birds and small mammals are successful at propogating
themselves, but have failed to demonstarte that the same is not true of
larger "non-stealthy" egg layers, living or extinct. These animals may
high egg mortality at this stage, but they lay enough eggs to keep
going, so so what? They have simply opted for a different path to success.
You have constructed a superficially plausible sounding just-so story that
is unfortunately unsupported by (or even contradicted by) what we know
about dinosaur and mammal evolution and the K-T extinction.
 
LN Jeff
O-