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Re: Megaraptor Claw



Steven Coombs wrote:

> the only material found of Megaraptor was the 
> famous "Sickle Claw", Ulna, and Finger and you can`t
> forget the "Metatarsal", But when you have all this
> material more associated with the forelimb why do 
> they say the Metatarsal and go right away that the 
> claw was bipedal?. And you  really only have a 
> Metatarsal. But you do not have Phalanges(Toe), but
> the finger bones which are Phalanges also. Could the
> Metatarsal be the "Metacarpals"? Than you would have
> an almost complete part of the right side of the 
> forelimb with the ulna bone. 
> Steve

I don't know the exact shape of the ulna, but if it is
posteriorly bowed, that would be a strong indication
of at least maniraptoran affinities. The manual
phalanx is interpreted as I-1. If this is spinosaur
material, then it should be a large easily diagnosed
element -  phalanx length equal to 300% the depth at
its proximal articulation. What would be helpful is if
I knew the morphology of the distal metatarsal III
(anyone care to volunteer some info?). I REALLY doubt
someone would confuse a metacarpal for a metatarsal,
but I suppose it's possible. One last comment on the
claw. I've heard it sheath tracts/grooves  are
asymmetric - just like some other dromaeosaurs. I
don't know if any spinosaurs evolved this
convergently, but i've never heard about it being
present in spinosaur unguals. I think there is a good
case for placing it with dromaeosaurs, but I would
like to hear what HP Mickey Mortimer has to say about
it since he has such a keen interest in these
critters. I'm more of a carnosaur/basal tetanuran
buff.....


BTW, I got that spinosaur phalanx synapomorphy from
Sereno, where he states "First manual digit length
300% the depth at proximal end." I'm not sure if he
meant the entire digit or the 1st phalanx or
ungual....anyone care to clear that up? thanks









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