Hoatzin & Archaeopteryx

[Amtoine Grant <ajgrant@eastlink.ca>]

Just thinking, has anybody compared the skeletons of Archaeopteryx. 
Especially with the controversy regarding manual digits 1,2,3 & 4 in 
theropods & extant birds, this could prove interesting. I've been 
wondering if the Hoatzin could be a late-surviving Archaeopteryid[to 
coin a phrase] - which would somewhat explain it being the only extant 
member of it's family or an example of regressive evolution, as has 
been suggested.
As a side note, not much has been said of Protoavis. I understand that 
the remains are fragmentary. Can it be discerned from what information 
is available whether Protoavis may have possibly been an ancestor of 
Archaeopteryx, or an example of convergent evolution, as in phytosaurs 
& crocodilians?