Re: Question about Archaeopteryx's (non) reversed hallux

[Tim Williams <twilliams_alpha@hotmail.com>]

Jaime Headden wrote:

>   Yeah, even *Confuciusornis* has a retroverted hallux.

Somewhat.  _Confuciusornis_ has an intermediate morphology, with the hallux 
directed medially or slightly posteromedially - according to Middleton's 
thesis.

> So this attribution holds for pretty much all of Pygostylia.

I'm not so sure about that.  Most basal euornithines (ornithuromorphs) do 
not have a retroverted hallux.  I think _Gansus_ has one (although the 
hallux is too short to be have been much use for perching), but 
_Yixianornis_ does not.  It doen't help that the hallucal condition is 
unknown or undescribed for most non-neornithean euornitheans.

Non-avisaurid enantiornitheans (including _Sinornis_ & _Concornis_) have a 
similar hallucal morphology to confuciusornithids, suggesting a medial (or 
slightly posteromedial) orientation.  Avisaurids show a unique condition, in 
which the end of metatarsal I is bent and the shaft is not twisted as in 
neornitheans.

Cheers

Tim