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John V Jackson wrote:
> _Conf._ is from the Yixian Formation - that is the earliest of the
> bird-carrying deposits known from China.  It is often said that the dating
> of the Yixian is controversial - J or K? but on reading this paper, it seems
> to me, the main controversy is where we decide to put the J/K border.  the
> Yixian seems to be about 140 myo give or take 5 (roughly combining two
> dating methods).
        If you believe those dates.  The biggest problem with our 
discipline is the thing that is the most wonderful about it.  It is, by 
necessity, interdisciplinary.  If done correctly, it is certainly one of the 
most interdisciplinary fields out there, hands down.  However, the system 
is set up to reward compartmentalism.  Thus, we end up coming out as 
either biologists, chemists, or geologists, historically with little or 
no cross-training.  A fossil ecosystem, as a modern one, is a 
manifistation of a complex interaction of componants of all of 
these three fields.  However, most people think it is perfectly 
acceptable to say, "I teach anatomy.  I don't need to know anything about 
what the cross-beds tell me about river directions."  Thus, you end up 
with people saying things like, "well there is an obvious stratigraphic 
seperation between _Confuciousornis_ and _Sinosauropteryx_ at Sihetun, so 
we can be sure that _Sinosauropteryx_ is ancestral to _Confuciusornis," 
when there has been no map made of the relationships of the various units 
at the site.   

        Along these same lines, paleontologists get a radiometric date and
tend to treat it as though it is gospel. "Oh well, we have a number now, 
rather than just a relative relationship.  It must be correct."  The 
paper that John is talking about above completely oversimplifies 
the situation, and neglects a number of very important problems 
concerning the radiometric dates that they cite.   

Josh Smith
University of Pennsylvania
Department of Earth and Environmental Science
471 Hayden Hall
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