Re: Paronychodon

["Jaime A. Headden" <qilongia@yahoo.com>]

Phillip Bigelow (bigelowp@juno.com) wrote:

<Okay, so your last statement means that _P. lacustris_ still remains a valid
taxon.  Some years ago, there was speculation (only on this mailing list, as
far as I can determine), that the Hell Creek Fm. _P. lacustris_ teeth might be
the dentary fangs of homalocephalid pachycephalosaurs.  I take it that this
hypothesis is unlikely, now?>

  Being able to figure out what group of dinosaurs some teeth belong to does
not mean it's a valid taxon. I adhere at least passingly to the hypothesis that
tooth-based taxa are not diagnosably unique to offer bases in substantive
taxonomy. Unfortunately, this means I would treat nearly all tooth-based taxa
as nomina dubia. In dinosaurs, that's 114 taxa, currently.

  In brief:

  There are some taxa that can be diagnoses by unique features, and some that
can be diagnosed by unique combinations of features that are, by themselves,
not actually unique two a few "levels" of relationship (i.e., any proposed
sister-taxon, ancestor, or descandant lacks the feature, making it
autapomorphous, or the combination thus unique). However, I do not think our
knowledge of dental anatomy in reptiles is sufficient to warrant diagnosing
species soley by teeth, as some tooth-based taxa may be synonymous
osteologicall, but cannot be compared directly (thus are incomparable). Even if
we were to find three different types of teeth on a single jaw, and were able
to synonymize three different taxa, I would argue there is enough doubt to both
prevent this synonymy and, by itself extension, argue against naming taxa
because of the potential. 

  It is sufficient, as Sankey, 2002 does, to use morphotype labels, without
using taxonomic nomenclature.

  Cheers,

Jaime A. Headden
http://bitestuff.blogspot.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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