Re: Rauhut's Thesis

[Darryl Jones <dinoguy@sympatico.ca>]

At 05:05 AM 7/6/2001, you wrote:
> "Although the chance of finding fossils
> of the population directly ancestral to later species is very small, a
> cladist can recognize a potential ancestor as one which: 
> a) shares derived features with the hypothesized descendant; 
> b) lacks derived features unique to itself; 
> c) is found stratigraphically lower than the descendants; and (it would
> be nice) 
> d) is found in a region later inhabited by the descendants. 
> Any fossil which qualifies for aspects a and b is called a
> "metataxon". Thus, potential ancestors are metataxa which occur
> earlier than the hypothesized descendants."
>  
> So a metataxon is technically a species that
> shares synapomorphies with its descendent, but hasn't developed
> apomorphies of its own.  I see how this could happen, but don't
> think any dinosaurian examples have been found
> yet.

I have heard of MOR 590 (Daspletosaurus sp.) described as a metataxon.
The justification for this was that it had derived features of BOTH T.
rex AND D. torosus, but had no derived features of its own.  I am
still waiting for a formal description of it (and other Daspletosaurus
material, for that matter) before this gains credibility.

On another note, why do we find out about finds from remote parts of the
world and get preliminary descriptions of them within a year, yet wait
ten plus years for descriptions of animals found within 500 km of well
established museums? ;-)

 

Darryl Jones  <dinoguy@sympatico.ca>

                   

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