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Re: Flight

Sean writes:

>> The hallux or big toe in _Archaeopteryx_ is opposed, which makes it easier
>> to cling onto branches; as opposed to theropods whos feet are composed of
>> non-opposable toes. Also the claws on _Archaeopteryx_ are apropos, since
>> they are very clean i.e. not abraided, which has been proposed to indicate
>> minimal contact with the ground, supposedly.
>Okay, the last part I follow, but as for the opposable toes, I'm not
>sure if that would mean too much, because didn't Velociraptor also
>have opposed toes, or am I misunderstanding? Boy, the sight of a
>Velociraptor in a tree is a truly scary thought...

"opposable" means that the digit can be moved into the hand or foot to
enable grasping i.e. your thumb is an opposable digit. The large toe of
most birds (aboreal ones anyway) is opposable in this sense. In theropods
the toe is *reversed* i.e. pointing in the opposite direction to the other
toes, but cannot close in to the rest of the toes allowing grasping, at
least I am unaware of any theropod with this ability.


cnedin@geology.adelaide.edu.au,   nedin@ediacara.org
Many say it was a mistake to come down from the trees, some say
the move out of the oceans was a bad idea. Me, I say the stiffening
of the notochord in the Cambrian was where it all went wrong,
it was all downhill from there.