Re: Armadillos at the K/T!

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

y

On Mon, 1 Oct 2001, David Marjanovic wrote:

> Have you got evidence that we _should_ decouple other extinctions? (Sorry if
> I'm annoying you by repeating the same questions all the time. I'm just
> trying to believe that you have more evidence than the three big mammals of
> LK western NA on which to build a hypothesis.)

No. The hypothesis comes from the simple observation that a
strategy that was once widespread is today non-existent.  With the
exception of crocs, all oviparous species avoid confrontation with nest
predators by concealing, laying remotely, or some other tactic.  Nest
defense is a last resort.  There are only two explanations for that a) the
strategy is defunct because predators restrict it; b) practitioners of
such a strategy didn't evolve because of reasons having nothing to do with
their fitness, e.g., because mammals were in all niches in all locations
before oviparous species could get there.  Giving me the benefit of the
doubt (and choosing a), this leads to the inference that this predator
regime must have started at some time.  A good place to look is at the
time when this strategy first began to collapse.  The next thing to do is
look for potential candidate predators.  So, you've got it backwards.