Re: A "new" phylogeny & methodology

[Tompaleo@aol.com]

Jerry said in part, 
<snip>
> 
>     The problem here, of course, is that there are no hard-and-fast rules 
>  about what constitutes "too few" and what constitutes "too many" 
characters 
>  -- how do we know if we've got too few to perceive reality, and how do we 
>  know if we've got so many that reality is drowned out by the noise?  
 
One man's character state is another man's preservation artifact, preparation 
artifact or just a bump!

Having said that (and the following) I will reiterate that I am not 
anti-cladist.  But I will play devils advocate.

This lies along the lines of something I suggested on this list several years 
ago. That being the creation of an _Internatiopnal Code of Cladistic 
Nomenclature_ (ICCN) replete with a consensus of rules governing what a 
character state is (in a general sense) and how many or few are useful in 
representing the specimen(s) being discussed. I also like Chris's suggestion 
of not only listing them but figuring them (imagine the page charges for a 
large set!) with the matrices. This seems like the best solution for the 
short term and until a database of figured characters per clade is built up 
with which we could all draw upon at some point (i.e., the WWW).
 
If  statistics can "show" that at present n-thousands of species are going 
extinct every year (and most of these species have yet to been discovered!), 
and as some argue regarding the US Census that _ststatistical sampling _ is 
the way to go precisely because one can never account for all the "character" 
in this country, then surely there must be some _statistical_ method of 
extrapolating or predicting the number of characters needed that would likely 
result in a representative sample (i.e., normal distribution) of characters 
possessed by the clade in question. 
Then the question becomes one of _identifying_ these characters and their use 
should pass as rigorous tests as the trees they would create. Parsimony is 
great for trees but like Josh, George, Tracy, myself and others believe that 
it's the characters "selected" and not just numbers that count. More science 
needs to be done on character recognition in fossil vertebrates. 

This could be standardized in such an ICCN. It could and should be done bone 
by bone and dentition by dentition.

More 
>  isn't necessarily better here (although the number of characters is 
>  certainly going to rise as more taxa are added -- an analysis of all 
members 

This seems logical. There must be a limit and a rigorous statistical method 
would help to reduce S/N ratio.


 As far as I can tell, we're still running on a sort of 
>  "common sense," intuition-based system for assessing whether or not the 
>  number of characters in an analysis is too few, enough, or too many.  And, 
>  of course, no two people are really going to agree on where the lines 
should 
> 
>  be drawn (which is why they haven't been drawn)...

Well, they need to be at some point or cladistics will implode upon itself 
and may be overturned on just those grounds. Common sense and intuition are 
valuable assets to any scientist but exclusive reliance on such a subjective 
quantity renders analyses based upon them are subjective at best.


Thomas R. Lipka
Paleontological/Geological Studies
Tompaleo@aol.com