Re: Laelaps and Brontosauria (was Re: Resending)

[Jay <sappororaptor@yahoo.com>]

--- Tim Williams <twilliams_alpha@hotmail.com> wrote:


> 
> You are correct when you say that Olshevsky put ALL prosauropods and 
> sauropods into his Brontosauria.  In fact, the only real reason Olshevsky 
> erected "Brontosauria" was because he also thought segnosaurs were 
> sauropodomorphs, and he need a name for the non-segnosaur sauropodomorphs.  
> Take out the Segnosauria (as he later did), and 
> Brontosauria=Sauropodomorpha.

Why not just abandon Brontosauria? It's original announcement was because of a 
purported
relationship between therizinosaurs and sauropodomorphs. Clearly, no one is 
realistically
advocating that anymore. 
Also, it's based on Brontosaurus, itself invalid by synonymy. 
We already have the names Plateosauridae, Plateosauria, Prosauropoda, 
Anchisauria - The topologies
of all of which could change following a revision in cladistics. Eg. 
Anchisauria originally
proposed in 2004 for the Anchisaurus + Melanorosaurus clade assumed a close 
relationship between
these taxa; now 1 year latter, Anchisauria could include Anchisaurus and all 
other sauropodomorphs
excluding Saturnalia, Thecodontosaurus, Plateosauridae, & Massospondylus. See
http://dml.cmnh.org/2005Aug/msg00240.html for this.

If topolgies are changing all the time, i'd take that to mean that the 
relationships aren't
stable. Until they become stable, i see little point in introducing new names 
or  
reusing/redefining redundant names beyond their original context. 

 
> Thus, a Prosauropoda+Sauropoda clade under current topologies would not have 
> *exactly* the same content as Brontosauria sensu Olshevsky.  However, I 
> tip-toed around this by saying the new Brontosauria would have 
> *approximately* the same content as the old.  A few basal sauropodomorphs 
> would certainly fall out - but probably no more than two or three 
> (_Thecodontosaurus_, etc) , and the vast majority of sauropodomorphs would 
> stay inside Brontosauria.  So, this new Brontosauria would retain almost all 
> of its original content.  And what's a few genera between friends?  :-)
> 
> Cheers
> 
> Tim
> 
> 
> 


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