RE: Erketu ellisoni online free access

[Ken.Carpenter@dmns.org]

Ah, not quite. Appendix 2 gives the coding for Erketu from the published matrix 
of Wilson 2002. Of 234 characters only 18! can be coded for Erketu. That is 
7.7% of possible characters! How can anyone tell me that we can assume to know 
so much from so little???? Keep in mind that a phylogenetic analysis is simply 
a form of statistics. Even Wiens' article notes a decrease in reliability of 
phylogenetic results when 75% or more of the data is unknown (his Fig 2). Here 
92% is unknown!!!!


Kenneth Carpenter, Ph.D.
Curator of Lower Vertebrate Paleontology/
Chief Preparator
Department of Earth Sciences
Denver Museum of Nature & Science
2001 Colorado Blvd.
Denver, CO 80205
 
Phone: 303-370-6392
Fax: 303-331-6492

for PDFs of some of my publications, as well as information of the Cedar 
Mountain Project: 
https://scientists.dmns.org/sites/kencarpenter/default.aspx
++++++++++++++++++

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] On Behalf Of David 
Marjanovic
Sent: Tuesday, March 21, 2006 2:20 PM
To: DML
Subject: Re: Erketu ellisoni online free access

> The data matrix has more question marks than known character states.

Not true. These are just the codings for *Erketu*. The rest is taken unchanged 
from Wilson (2002), except for one character state of one taxon explained in 
the text.

> Nevertheless, the results pretend that we know something about the 
> question marks (as if they weren't there).

How so? At worst it lets us apply parsimony to infer what the true states are 
-- _after_ the tree has been made.

> There is nothing wrong in science to
> say "I don't know" than to pretend that we do.

But we do know something. We know that, according to that analysis,
*Erketu*(*) is with quite some certainty a somphospondyl. The bootstrap value 
of that clade is 89. We can also be fairly sure, though less so, that
*Erketu* is not a member of the smallest clade that contains *Malawisaurus* and 
*Alamosaurus*, because that clade has 79 % bootstrap support. These values are 
better than almost everything inside the latter clade (51, 56, 60, 70, 81 and 
83) and much better than the, one should think, quite obvious Neosauropoda 
(less than 50 % -- not shown).

But then I have my doubts about Somphospondyli. It seems to be held together 
mainly by its somphospondylous vertebrae... right?

* Meant to be pronounced the French way. The etymology section says "Erketü" 
and "Yesügei". -- BTW, in spite of this the paper is totally full of typos. 
Some are consistent throughout the text and references, so may be genuine 
errors, such as "Tshuihiji" and "*Mamenchisaurus houchuanensis*".