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Re: Mammalian success and egg predation,



On Thu, 13 Jun 1996, JCMcL wrote:
> I think that the long dominion and sheer variety of dinosaurian
> evolution suggests that dinosaurs early worked out any problems they
> may have had with eggs...

This sounds like a structural engineer trying to overcome a design 
problem, a problem such as knowing how to span such and such a distance.  
Those sorts of problems may be very difficult but once they 
are solved, they _stay_ solved!  I would argue that in a dynamic system 
such as in a biological community over a great deal of time, problems do 
not stay solved because other "engineers" are figuring out ways to get 
around the solutions.  Who is to say that the period of the 
dinosaurs dominion was not one long evolutionary arms race driven, in 
part, by the primacy of defending a non-stealthy nest?  In this view, their 
diverse morphologies cease to be evidence of dinosaurian security, 
rather they were diverse solutions to an ongoing problem!

> ...and that anything that mucked  about with their eggs was a fair 
> candidate for leaving fewer genes in the future.

But big dinosaurs could run smaller dinosaurs off their nests.
Non-defended nests could be robbed.  A cuckoo-style dinosaur could
parasitize a nest.  Predators could get so hungry that the risk of
leaving fewer genes due to being throttled by a defensive parent was
smaller than leaving fewer genes by starving to death.  And then, it
is possible that some very new "engineers" came along and attacked the
dino eggs in a way that they couldn't respond.  For they had been
solving problems of big against big.  And the better they got at doing
that, they must of necessity be less able to deal with small mammalian
or avian stealthy egg predators.

I know we don't know whether or not this happened.  All I'm trying to
do is establish it as an alternate hypothesis.  With regard to mammal
competency, did you see the latest _Nature_?  There is molecular clock
evidence which suggests that mice, rats, squirrels, porcupines emerged
independently, from different ancestors.  In other words, there may be
no such things as rodents anymore!  Now, I have been accused of
dragging any old evidence to fit my idea, so here I go again: if the
teeth (gnawing incisors) of these mammals are indeed convergent, and
we know that there were also "rodent-style" gnawers among pre-K/T
multis, and we also know that placental mammals were diversifying well
before the K/T, then isn't it, to use a Gouldian modifier, "almost
surely" likely that there were some rodent-style gnawers who would be
egg-eating naturals?