Re: Pterosaur diversity (was: Re: Waimanu)

["Jaime A. Headden" <qilongia@yahoo.com>]

David Marjanovic (david.marjanovic@gmx.at) wrote:

<Sure, but *Leptoceratops* is just as Maastrichtian as *Triceratops*.>

  Hence the problem of using gross lumping of groups to provide trends of body
size increases. Leptoceratopids on the whole appear to get _smaller_ towards
the end of the Cretaceous, with mid-Cretaceous *Magnirostris* of moderate size,
then Campanian/Maastrichtian *Udanoceratops* and *Montanoceratops* of large
size, and then Campanian--Maastrichtian *Leptoceratops* at quite small stature.
This is of course allowing that time reflects lineage (which it does not appear
to in a good number of clades). Tracking size-based changes along lineages then
correlated to time would be a factor of applying time to the branching orders,
rather than calculating size during time periods. I agree with Gould and Tim
that Cope's Law is an artifact of perspective, even if somewhat true or
applicable, as it depends heavily on how much data you use to correlate your
size-based changes to time.

  Cheers,

Jaime A. Headden
http://bitestuff.blogspot.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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