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PAMPRODACTLY IN APTERYX



<<I have examined numerous stuffed kiwi specimens (in which the skin 
fixes the hallux in place, in skeletons the position is often altered) 
as well as some live ones at the National Zoo. The hallux is NOT 
reversed. It is laterally oriented, and appears no more reversed than 
the hallux in the huge Tyrannosaurus trackway.>> 

Obviously something is wrong here.  I have looked at some _Apteryx_ 
skeletal mounts and I cannot see a non-reflexed hallux.  I DO see a 
hallux the is proximally placed and whose dorsal edge (as compared to 
other "normal" birds) is facing perpendicularly to the tarsometatarsus.  
I checked through some literature and apparently Osborn put a  reflexed 
hallux on _Tyrannosaurus_ based on _Apteryx_.  McGowan (1982; Journal of 
Zoology, v. 197) illustrated a (partially) reflexed hallux on _Apteryx_.  

Also, I have become aware of some work that suggests that the reflexed 
hallux found in some theropod trackways is an artifact of preservation 
(Gatesy and Middleton 1996 JVP 16 Abstracts: 37A).  All known theropod 
feet preserved show conclusively that the halluces were not reversed 
(Norell and Makovicky 1997; Amer. Mus. Novitates 3215).  Lateral 
extension was was POSSIBLE, but I find it unlikely at the time given 
preservational facts in both birds and dinos.  

Plus, it is unreliable to base your (GSPaul) claim that relexed halluces 
do not matter in phylogeny.  Many flightless birds (diatrymids, 
bustards, etc.) have relexed halluces, and _Apteryx_ at least moderately 
so.  To base such a claim on such an aberrent bird is just bad.  One 
reason for the at least incipent non-reflexion of the hallux in 
_Apteryx_ may have to do with the shortness and large breadth of the pes 
(including tarsometatarsus) in the bird. All species of _Apteryx_ are 
known for their short feet and the shortness of the metatarsus may have 
something to do with the apparent rotation of the hallux in _Apteryx_.  
The ancestral reflexed hallux in _Apteryx_ was probably on the typical 
avian arrangement.  

Matt Troutman

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