RE: Species [ was: Re: Hadrosaur nomenclature]

[jonathan.r.wagner@mail.utexas.edu]

Quoting "R. Irmis" <rbi@dana.ucc.nau.edu>:

> I still am not convinced that the criteria by which paleontologists diagnose
> species is at all accurate, considering the wide intrageneric and
> intraspecific ontological variation that is seen in modern taxa.  Its easy
> to do an ontological diagnosis on extant taxa, because you can see what kind
> of variation occurs in related forms, but I think it is next to impossible
> to do this in extinct taxa.  Perhaps we should arbitrarily define
> "ontotaxa"?  It would be arbitrary, but would provide some sort of standard.

    If your point is to provide a "classification," the deliberate shoe-horning 
of organisms into groups, then an arbitrarily-defined set of criteria would be 
fine. If your point is to recognize real entities, then it is (clearly) not 
acceptable. That the criteria used by paleontologists might not be "accurate" 
presupposes that there is an "accurate" set of criteria. This again relates to 
a concept of species as human constructs.

     It is alternately possible to suggest that paleontologists are not 
correctly recognizing (real) species, due to the criteria they are using. this 
is an operational consideration, contingent upon the reality of species, but 
independent of any a priori understanding of what the recognition criteria 
should be (possibly in appreciation of the fact that species give the criteria, 
and not vice versa).

     I have already agreed that many named fossil species are likely founded on 
members of other named species (i.e., their names are synonymous). Indeed, I 
would *never* disagree with the notion that paleontologists, especially in the 
past, often have not approached the naming of species with a clear idea of 
biological and geological circumstances. The aspects that HP Holtz pointed out, 
such as preservation, intraspecific variation, etc., all need to be considered 
rigorously. I do not think that the apparent failure to recognition species 
accurately in the fossil record (however testable such recognition may or may 
not be) does not itself make the idea of recognizing fossil species any less 
valid than the recognition of extant species.

     I am unclear as to what you mean by an "ontological diagnosis." For that 
matter, I am unsure that diagnosis of any kind is the best way to recognize 
species. A diagnosis would be, of course, a fundamental part of referring 
specimens to a species, and detailed morphological comparison usually plays a 
major role in the recognition of species. But that's a debate for another day 
(and, I must admit, it is beyond my ability to support at this time).

Later,

Wagner

P.S. The EPB is a speccific method for reconstructing soft-tissue morphology. 
The method appropriate for suggesting an expected range of variation in 
dinosaurs would simply be the application of parsimony to character 
optimization (usually using DELTRANS, or delayed transformation, for 
conservatism).