Re: Size trends (was: pterosaur diversity)

[Michael Habib <mhabib5@jhmi.edu>]

> There were certainly some big (really, really big) sauropods in the 
> Late Cretaceous.  (I have to say I don't know too much about 
> _Bruhathkayosaurus_).  However, there were more really, really big 
> sauropods in the Late Jurassic, and more not-so-big sauropods in the 
> Late Cretaceous.  I was actually a little surprised by this trend.

Which is one reason that not all analyses agree with regards to the 
size trends.  It depends a great deal on whether or not the results are 
weighted by the number of large species or if an analysis simply looks 
for positive or negative change along major branches.  There's a 
notable difference between the frequency of size increases and the 
magnitude of such increases in size.  I seem to recall that some of the 
older literature that looked at Cope's rule didn't properly address the 
difference (statistically, at least).

Cheers,

--Mike Habib