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Re: Weird classification

Rescued from truncation:

After reading about them, I have noticed something odd abuot the
hadrosaurs= and ceratopsids:=C2=A0the genera and subfamilies=C2=A0seem
to correspond i=n an odd way, i.e. the lambeosaurines and
centrosaurines seem to go togethe=r (they decline at about the same
time) and the hadrosaurines and ceratopsi=nes do (they both were the
last around, if you know what i mean). What i'm =really trying to get
at is this: its possible that *Pachyrhinosaurus*, Syra=cosaurus etc.
belong to a large Centrosaurus/Monoclonius, Hypacrosaurus mer=ges w/
lambeosaurus and corythosaurus. I believe that, also, Greg PAul did
=this in a book. I mean, if you think about it, dinosaur
classification shou=ldnt differ from all of God's other creatures,
which has been brought up be=fore. If these animals were mammals or
fish, there would (should)=C2=A0be a= major lumping. Obviously theres
also the fact that postcranially, the cera=topsians differ very little
from species to species. Whats the crowd's opin=ion on all this?___

I'd suggest a comparison with the decline of perissodactyls with the
rise of artiodactyls; horses compared with bovines as a more specific
example. I'm not aware of much postcranial difference in the latter
example except size, proportions and the odd anatomical detail (number
of toes reduced in horses, width of snout in bovines).
With all this I mean to say that an evolutionary lineage, more often
than not, shares a number of constraints, some with an ecological
expression, and these are usually the issue at hand when an entire
group declines.
As such I'm not sure there should be lumping in the dinosaur groups
you mention: if by most accounts the selective pressure behind the
headgear was sexual then diversity is actually underestimated as one
cannot account for color, only shape.

Renato Santos