Re: Cretaceous taeniodont

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

On Fri, 9 Apr 2004, Eric Martichuski wrote:

> No one has yet been able to give me a really good answer as to why the
> megafauna of the Mesozoic was so _mega_...but the fact that is was (and that
> it ran the gamut all the way down the line),seems like the obvious candidate
> for whatever _did_  put the apparently pretty hefty selection cap on the
> size of early mammals.

The stock answer is that bigger is better in terms of energetics.  But I
reject this since, if you look at a non-log graph of this function, there
is basically no benefit above horse size.  A better hypothesis is nest
defense.  Mammals can run away with their baby inside.  Dinosaurs had to
stay (presumably) and protect a single location for up to 3 months.  This
necessitates armed combat.

> 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.