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Re: Maidment & Wei, 2006

I haven't read the article yet, but if the specimen is likely distinct (based on geological time for instance) but not diagnosable, couldn't one refer to it as Stegosauria taxon A and still use it in diversity studies? One could state the caveat that it is not diagnosable, so readers understand the basis for the diversity database. And while one might choose to use this for dinosaurs, it might be less advisable with some groups of Cenozoic mammals where the record is much better and the diversity pattern is less likely affected by undiagnosable taxa, although it might have a greater effect on first and last records.


Mike Taylor wrote:
Michael Mortimer writes:
 > There are lots of dinosaurian nomina dubia and unnamed specimens
 > which are near certainly distinct from named species based on
 > provenence alone if nothing else, but since we can't prove this
 > validity, it doesn't mean much for diversity studies.

I disagree!  In fact, I would say the exact opposite: that _although_
these specimens cannot be diagnosed and named, this "cryptic
diversity" _is_ significant for diversity studies -- and it's a
failing of diversity studies up till now (including my own) that they
only count taxonomically valid animals.

See a version-1 Tetrapod Zoology post (by Darren Naish) for more on

 > I agree the concluding sentences of Maidment and Wei are poorly
 > worded, but I think their main point was that the _known_ diversity
 > of stegosaurs was not significantly higher in China than in Europe
 > or America, contra Dong.

Au contraire, _known_ diversity _was_ higher in China; it's _named_
diversity that is not.

_/|_ ___________________________________________________________________
/o ) \/ Mike Taylor <mike@indexdata.com> http://www.miketaylor.org.uk
)_v__/\ "I've got an allergy to Perrier, daylight and responsibility"
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