Re: Defining Ornithischia 2

["Mickey Rowe;893-2446" <mrowe@lifesci.ucsb.edu>]

The listprocessor didn't like the following message because it thought
David was trying to submit a "put" request.  Oh for the language
recognition capabilities of the computers on Star Trek <sigh>.


----- begin forwarded message ----
Date: Wed, 03 Oct 2007 23:19:43 +0200
From: David Marjanovic <david.marjanovic@gmx.at>
Subject: Re: Defining Ornithischia 2
To: DML <dinosaur@usc.edu>

----- Original Message -----
From: "david peters" <davidrpeters@earthlink.net>
Sent: Wednesday, October 03, 2007 8:13 PM

> If anyone wants to defend the placement of Lotosaurus within the 
> Rauisuchia, or Effigia within the Crocodylomorpha, or Silisaurus within 
> the wastebasket taxon, Dinosauromorpha, reach me here. I'd like to hear 
> what you have to say. (Yes, I've seen Irmis et al. 2007 and it has 
> problems galore.)

Put up or shut up :-)

> Those taxa became nested where they became nested because there was no 
> more attractive pairing for PAUP to discover among the 175 participants in 
> my analysis. Frankly, I don't care where they end up. I just report the 
> findings. And they are robust.

Has your matrix changed since you privately sent me these results and a kind 
of list that kind of explained the distribution of the character states over 
a year ago?

Because if not, I can only repeat those comments: you used way too few 
characters; you kept all characters unordered; you didn't even try to keep 
size- and ontogeny-related characters out of the matrix; you used arbitrary 
cut-off points for delimiting the states of continuous characters (that 
includes the size character -- size itself was a character in your matrix); 
and you used your own badly justified, sometimes outright wrong, 
interpretations of (2D) line drawings from the literature to code your taxa.

> re: the tarsus in Lotosaurus and Effigia: like all archosaurs 
> (=crocodylomorphs + dinos) it had bipedal ancestors with small, 
> comma-shaped calcanea (ala Turfanosuchus). As in derived crocodylomorphs, 
> and unlike most other dinos, that spur expanded along with the evolution 
> of quadrupedality. Or, in the case of most dinos, it disappeared. But you 
> can still see a remnant in some prosauropods and Pisanosaurus.

That _is_ interesting and should be looked at.

> Nesbitt's dentary on Effigia is topographically the paired predentary, for 
> instance, and his extended surangular is the result of fusion with the 
> toothless dentary.

And the external mandibular fenestra extends all the way to the predentary, 
excluding the dentary from the ventral jaw margin?!? That would be 
completely unique. For short dentaries and large mandibular fenestrae, have 
a look at derived oviraptorids like *Citipati*.

You can't simply make revolutionary assumptions and base your codings on 
them! You need to describe and defend these assumptions in detail and 
publish them, whether in the same paper or in an earlier one. Instead, you 
don't even seem to have noticed how revolutionary they are = how far you 
stray from the principle of parsimony.