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The problem with multivariate analysis.
Workers have been trying to decipher the phylogeny, nomenclature and affinities
of Pterodactylus and Rhamphorhynchus for over 150 years. They see differences
and similarities. They try to quantify their observations in an attempt to
answer the question: Are there multiple species improperly lumped into
nomenclature wastebins? Or are many specimens properly lumped into single
Mateer 1976, and Bennett 1995, 1996 both performed statistical studies on
pterosaurs using skull and long bone measurements in an attempt see how chart
dots grouped and lined up. Their work has been almost universally accepted.
The problem is this, according to a larger cladistic analysis examining dozens
to hundreds more characters: the variation within these taxa do not occur so
much at the long bones, but rather at other relatively minor parts of the
skeleton: teeth, toes, fingers, face, pelvis, etc. After all, all properly
named Pterodactylus and Rhamphorhynchus specimens are related at the genus
level (which may still be too broad when compared to extant taxa, but thatâ??s
for another day). Perhaps that is why both Mateer and Bennett tended to lump
multiple and various specimens into single species, applying observed
differences to ontogenetic stages of development.
One might have similar results performing a similar sort of statistical
analysis on a selection of passerine birds or microbats using only long bones
to create a data table. (Now thereâ??s a project!) The overall proportions
[just guessing here] appear to be grossly similar in a number of taxa despite
some variation in size and genus. That may be because both taxa have
aerodynamics operating as a selective force. As in pterosaurs, the ignored
variation, it would appear, would only show up in the smaller overlooked
details of beak and ear shape, etc.
So while the statistical analyses of Mateer and Bennett are interesting
exercises, if one wished to determine affinities at the species and genus level
in flying taxa then it would appear that one must perform more detailed
cladistic analyses and probably create reconstructions of the roadkill to
improve understanding, especially when trying to argue a case. You all know how
educational Greg Paul reconstructions can be. The differences and similarities
are illuminated almost at first glance.
Have a great time in Denver!
Bennett, S. C. Â 1995 statistical study of Rhamphorhynchus from the Solnhofen
Limestone of Germany: Year-classes of a single large species. Journal of
Bennett, S. C. Â 1996 Year-classes of pterosaurs from the Solnhofen Limestone
of Germany: taxonomic and systematic implications. Journal of Vertebrate
Paleontology, 16:432- 444.
Mateer, N. J. 1976 A statistical study of the genus Pterodactylus. Bull. geol.
Inst. Univ. Uppsala 6, 97â??105.