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Re: PAMPRODACTLY IN APTERYX
Matthew Troutman wrote:
> <<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).
Norell and Makovicky have a very well preserved Dromaeosaurid foot, and
for that specimen, it doesn't have a reversed hallux claw.
All you have to do is look at the back end of Metatarsal II to see if MT
I fit there. In Allosaurus there is a small teardrop indatation on MT II
where MT I fits. Strangely in Albertosaurus/Gorgosaurus MT at the AMNH
(I looked at a half a dozen of them) all had TWO teardrop indentation's,
one above the other. Why? I don't know, but MT I fits perfectly there.
The question is which way did the claw face? Norell and Makovicky show
that in Dromaeosaurid's the claw faced backward, away from the foot, not
toward the foot.
so the toe is behind MT II in some thereopods, Ornithomimid's lack MT I.
> extension was was POSSIBLE, but I find it unlikely at the time given
> preservational facts in both birds and dinos.