Re: Distributions of morphological characters and more

[David Marjanovic <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Nick Gardner" <nick.gardner@gmail.com>
Sent: Wednesday, August 17, 2005 4:19 PM

> Has anyone else noticed there is a tendency in many cladistic analyses
> (especially ornithischians) to focus on cranial characters, while
> paying little (if any) attention to those of the postcrania?

Yes. I've also noticed that the chapters on Ankylosauria, Pachycephalosauria 
and Ceratopsia in both editions of The Dinosauria almost completely ignore 
the postcrania.

> Is this an artifact of limited material or research
> being done, or does it truly represent a lack of characters from the
> postcrania? I'm inclined to believe the former.

So am I, because the number of characters used in the most recent published 
ornithischian analyses is way below those for theropods. The basal 
ceratopsian analysis (You, Dodson, and various friends) are catching up, but 
the Basal Ornithopoda chapter in The Dinosauria uses only 54 characters, of 
which only 30 are published in the supplementary information!!! Even my 
make-believe bird analysis has 67 characters! Plus <trying to calm down> 
this chapter claims to find the former Hypsilophodontidae as paraphyletic to 
Iguanodontia. It is unfathomable why they didn't include _any_ iguanodontian 
in their tree or matrix. They find evidence that *Gasparinisaura* is not an 
iguanodontian? Great, but why don't they test that idea in their 
phylogenetic analysis??? Based on the synapomorphies of (*Gasparinisaura* + 
*Parksosaurus* + *Thescelosaurus*), which are given in the text and occur in 
Iguanodontia as well, the autapomorphies of Iguanodontia, which are given in 
the text of the following chapter and IIRC don't occur in the abovementioned 
clade, and the fact that David Norman has coauthored the first chapter and 
authored the second (which gives me some hope that the two chapters won't 
contradict each other), I make the ed-ju-ma-ca-ted guess that Iguanodontia 
is the sistergroup of (*Gasparinisaura* + (*Parksosaurus* + 
*Thescelosaurus*)). But, you see, I'm supposed to rely on that kind of 
reasoning for my thesis.

> And finally, has there been any published critique of the
> "compartmentalization" technique employed separately by Sereno,
> Vermeij, and Carpenter?

Probably not. I guess everyone guesses that those authors only cut up their 
matrices to keep survivable running times on their computers, which is a 
problem that simply goes away due to Moore's Law.