Re: Cretaceous taeniodont

["Eric Martichuski" <herewiss13@hotmail.com>]

> > It's like having an army with BB guns...and the other side has A-bombs, 
> Uzis
> > _and_ BB guns.  You try and develop an Uzi and they're _still_ ahead of 
> you
> > (with more trumps in storage).
>
> But dinosaurs were not operating as a _team_.  And one could say that
> dinos just above mammals size only possessed BBs, too.  Why didn't mammals
> move into that niche?  I think the answer is in the dinosaur vs. mammalian
> life history/body plan.

It doesn't matter that the dinosaurs weren't acting as a team.  All that 
matters is that, to the mammals, they appear as a solid front.

Mouse sized mammals are being preyed upon by chicken sized dinos.  Mammals 
become chicken-sized.  They are then preyed upon by the turkey-sized dinos 
who've stepped up to the place and find chicken-sized tidbits convenient.  
Since it's unlikely that the newly enlarged mammal is going to have any 
decent adaptation to its new predators (for one thing, much harder to run 
hide when you're bigger, which would probably be it's instinct), the whole 
chain gets knocked down before it starts.  There would, in fact, be 
selection pressure _against_ being larger, since the larger mammal, while 
escaping chicken-sized dinos, would be ignorant about the specifics of new 
threats.

I portray it as a stair step when it would have been a ramp...but I know of 
no species that has managed to evolve to an _intermediate_ size, where it's 
too big for one set of predators but too small for the next.  The only 
ultimate safety in size lies in being bigger than _everything_, which the 
dinos managed with some success.  Mammals, OTOH, wouldn't be able to evolve 
fast enough to reach that point before being eaten.  If you evolve in 
lock-step with your local predators, you can get bigger, but the mammals 
existed in a world where all the predator niches were already filled.

Eric
______________________________________________________________________
"There is no other wisdom,
And no other hope for us
But that we grow wise. -- Diane Duane
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