Re: Pterosaur diversity (was: Re: Waimanu)

[Tim Williams <twilliams_alpha@hotmail.com>]

David Marjanovic wrote:

> Here's hoping for more material of *Puertasaurus* (Maastrichtian, and 
> mighty big).

Yes, there was some enormous titanosaurs that existed in the Late 
Cretaceous.  _Pelligrinisaurus_ (Campanian) was pretty big too, and let's 
not forget _"Antarctosaurus" giganteus_ (Turonian/Coniacian, I think).  But 
on average, sauropods appear to have declined in body mass heading into the 
end of the Cretaceous.

> > [...] ceratopsians certainly appear to have gotten bigger
>
> Ceratopsids, yes (probability of the increase I get being all random = 
> 0.511 %, so the increase is highly significant... if it isn't an artefact 
> of coding them all as either "Campanian" or "Maastrichtian", that is). But 
> if I just add 5 more species to get Coronosauria complete (*Bagaceratops*, 
> *Protoceratops* spp., *Leptoceratops*, *Montanoceratops*), the significance 
> shrinks below what >is considered acceptable (it rises 26-fold to reach 13 
> %).

OK, that surprises me.  I would have thought the effect of those runty 
mid-Cretaceous psittacosaurs and "protoceratopsians", at one end, and the 
ginormous Maastrichtian ceratopsids (like _Torosaurus_ and _Triceratops_), 
at the other, would have given you a statistically significant trend.  So 
much for my back-of-the-envelope calculations!  There's that "psychological 
artifact" at work.

> (That is... forget the numbers anyway, at least their exact values. I coded 
> *Zuniceratops* as Cenomanian. Shit.)

Yes, I suppose the coprolites would get bigger too.  But here we are really 
constrained by taxon sampling.

Cheers

Tim