Re: Cretaceous taeniodont

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

On Mon, 12 Apr 2004, Tim Williams wrote:

>
> John Bois wrote:
> I think one can dispute Feduccia's transitional shorebird theory and
> disagree with your "evidence" at the same time.  BTW, your assertion that
> "new birds" eradicated "old birds" is a hypothesis, not evidence.

Yes.

>  You'll
> have to compile data to support this hypothesis before you can use it to
> support other hypotheses.  (Also, what is an "old bird".  If you mean
> enantiornithines and/or basal ornithurines, these appear to have been much
> more successful in the LK than our modern friends, the neornithines.)

I did mean neos--but I suppose I can have it both ways: whatever combo of
birds that did in pterosaurs.
>
> >- decrease in dino diversity before the K/T
>
> This is based on late K North America alone, right?

Yes...I believe it is the only still that dino extinction is
recorded?

> >- increase in mammal size just before the K/T (if this is demonstrated)
>
> "If" indeed.  If this can be demonstrated, then it qualifies as "evidence".
> Until then...

Yes...and it's just not cricket to crow every time a big pre-K/T mammal
is found.

> That reminds me, what were the ecological niches of these bigger Mesozoic
> mammals (_Didelphodon vorax_, _Cimolestes magnus_, _Schowalteria clemensi_)?
>   Can we be certain that they actually competed with dinosaurs?

I'm not proposing that they outcompeted small dinosaurs, but that small
were forced out by other predators--the same crowd that worked over the
pterosaurs--leaving an opening for mammals.