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Re: Dino size: go on, laugh at me

On Mon, 26 Jan 1998, Sue Blakey wrote:

> Okay, guys, you can laugh at my stupidity on this one, but I need some 
> help.
> A second grader in Spain has requested the answer to this question: Why are 
> dinosaurs so big?

Don't feel foolish.  No one knows why they were so big.  The most common
answer is that an evolutionary arms race between predator and prey
resulted in bigger and bigger dinosaurs.  I think a better answer is that
their nesting strategy led them to large size.  A pregnant mammal can run
away from predators with baby safe inside.  A dinosaur must stand and
fight or abandon baby.  Relative to mammals this put a premium on large
size--the better to protect baby.  Mammals, on the other hand, are
selected for speed.  This idea is supported by the fact that
nest-defending snakes tend to be larger than non-defenders.