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Re: Cladistic question (was Re: Centrosaurines)

> Here's an interesting thought.  What would happen if someone was to take a=
>  cladogram, and superimpose it onto the geologic time scale (a combination=
>  of cladistics and phylogeny)?  Would this be informative, or merely=
>  garbage?  At first glance, it could be a powerfull tool.  One could use=
>  cladistics to see how animals are related (something that the time scale=
>  could obscure), and then put in the timescale, where it could be more meani=
> ngfull.

A lot of coffee-table style books, some posters (George Olshevsky's 
Ankylosaurian family tree) and "guide books" on dinosaurs already do 
that...the only problem is that exact timing for splitting is very hard to
pin down other than saying for example "sometime in the early Jurassic"...

All my dinosaur cladograms are superimposed on the geologic timescale.  You
can get a feel for evolutionary changes.  If you wish to do the same I 
suggest one other factor you should add...superimpose the world-wide 
stratigraphy (lots of changes during the middle Jurassic and early 
Cretaceous) to the cladogram (especially if you know the timing for 
continental connections...very helpful for late Cretaceous although not 
so helpful for late Triassic).  

---John Schneiderman (dino@revelation.unomaha.edu)