Re: Big = Old = Advanced?

[John Bois <jbois@umd5.umd.edu>]

I agree with your post except for this bit.

John Bois wrote:

> > Birds can fly away to places of reduced predator density (and swamp the
> > few predators that are there).  Dinosaurs had no particular skill
> > differential which would enable them to put such huge distances between
> > themselves and those other dinosaurs which would eat them.

J.M. replied:
>      Clams live in a predator rich environment, and needless to say
> aren't going anywhere.  They compensate for this by producing a HUGE
> volume of eggs.  Sea turtle hatchlings deal with devastating predation
> both on the beach and in the water.  Escaping to areas of reduced
> predator density is not an option for numerous animal species, and high r
> reproductive strategies are an effective way of dealing with it.

I'm not sure I understand your point.  I was arguing that relative to
_birds_, non-avian dinosaurs were at a relative disadvantage because they
probably couldn't put as much distance between their nesting grounds anfd
their "home" predators. The comparison is useful because of their
relatedness and similarity of reproductive styles, i.e., they both lay
shelled eggs.  As such their reproductive effort is relatively expensive.
And, they are both fixed-site modes, i.e., with some exceptions possible,
most dinosaurs didn't regualrly move their eggs.  Clams achieve almost
instant dispersal from wave and tide action.  The strategy relies on the
anonymity of the plankton and the vast numbers of extremely cheap eggs
they can release.  Sea turtles may be constrained to lay eggs on land.
So, they make the best of a bad lot by laying on an island in the middle
of nowhere.  It is in fact utilizing a skill differential that its
once upon a time "home" predators didn't have--it could swim thousands of
miles away.  Yes, it still suffers predation but it minimizes it by laying
and leaving.  In this way, and by satiating predators (I like swamping
better because it probably reflects reality more), it survives.
        I'm not sure I addressed your point, though.