Re: My Thoughts on Limusaurus' hand

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

> There is a proximal dorsolateral process on metacarpal III in 
> coelophysoids and Limusaurus, similar to one on metacarpal II in some 
> basal tetanurines like Guanlong. Yet Guanlong also has a process on 
> metacarpal III, which partly covers metacarpal IV, even though the latter 
> is not illustrated in Xu et al.'s paper. Acrocanthosaurus and Allosaurus 
> also have a processes on metacarpal III, while "Szechuanoraptor" lacks 
> processes on metacarpals II or III. This process on metacarpal III of 
> tetanurines could be homologous to the process on III in basal theropods 
> as easily as it could the process on II.

*Limusaurus* can also be said to have such a process on mc II. At least it 
looks that way in the cross-section drawings the supp. inf. provides.

> Xu et al. ran a phylogenetic analysis which determined that when 
> characters states are ordered, the resulting tree assuming tetanurines 
> have digits II-III-IV-V is six steps longer than if they are assumed to 
> have digits I-II-III-IV. The length of the unordered trees is equal, but 
> leaving characters unordered potentially leads to ridiculous "intermediate 
> synapomorphies" like coelophysoids and Herrerasaurus being diagnosed by 
> having a single phalanx on digit IV (not more or less) or taxon being 
> diagnosed by having an intermediate ratio, as opposed to relatives with 
> low and high ratios.

This is a very important point: potentially continuous or meristic 
characters must be ordered (Wiens 2001).

> Furthermore, neither Xuanhanosaurus, "Szechuanoraptor" or Megaraptor were 
> included in their matrix

Wow. I didn't even notice.