Re: Cretaceous taeniodont

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

> The increased diversity is totally ridiculous compared to anything
Cenozoic.

In terms of ecological impact I don't think you can say that!  Skunks,
racoons, possums, badgers, coatis, rabbits, armadillos, ferrets, weasels,
etc., have a _tremendous_ impact on community structure.  I believe every
extant community has populations of in this size range.  The apparent fact
that during most of the Cretaceous (NA, at least) this size range was
absent...and that just before the terminus their diversity spiked may mean a
great deal!  Which gets to my question: what constitutes a spike?

> In addition, all big Mesozoic mammals that have been mentioned in this
> thread were carnivores sort of like a weasel or badger -- that's not a lot
> of niches.

>From the insectivory insectivores, to the diet of the above (including small
mammals, birds, eggs, fruit, grain, and just about everything else)--on what
planet does this not represent a significant leap in niche utilization.

> (The one that hasn't been mentioned, *Kollikodon*, is a problem
> of its own...)

Can you elaborate?

> Late Jurassic multituberculates
> flood all vertebrate microfaunas, but they seemingly appear out of
nowhere.

Presumably, they all won a free pass to exist.  Look, all these speciation
events are conditional.  Just because we are too far away in time and
knowledge to know what the conditions are, doesn't mean species'
distribution is random!  Nor does it mean that size distribution w/in clades
is random.  On the contrary, it's most certainly under very tight control.