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Re: Tyrannosaur #1 pedal digit and hollow bones



In a message dated 9/1/02 11:18:48 AM EST, dinoguy@sbcglobal.net writes:

<< It seems that every mount of _Tyrannosaurus_ I have seen gives these
 tyrannosaurids reversed #1 pedal phalanxes, so that the first toe (the
 one off the ground) opposes the other three toes as in perching birds
 (though off the ground, so there could not be a grasping function).  Is
 this, in fact, how the phalanges articulate with the foot, or is it
 impossible to tell? >>

In theropods above the herrerasaurian grade the first metatarsal articulates 
loosely and distally with the second metatarsal, either at the side or at the 
back (the more advanced condition). In life, this articulation was quite 
loose, something like that of the human thumb, which can rotate about 90 
degrees from a position more or less in line with the other digits to a 
position opposing the other digits. This is why the first pedal digit of such 
theropods is often found in line with the other digits as well opposed to 
them.