Re: Bird Origins + Ref:

[jdharris@csn.net (Jerry D. Harris)]

>Could Protoavis be related to Megalancosaurus??
>[The shared tetradactyl hand makes this at least *possible*].
>

        Oops!  My error -- I said that _Megalancosaurus_ had a tetradactyl=
 manus, but it's got a pentadactyl one.  My mistake -- sorry for the confusi=
on.

        It's a bizarre manus, too:  digits IV and V seem to be opposable in=
 one direction, while I-III go the other way.  Perfect for grasping limbs=
 and such, as one would expect in arboreal animals, but not in a protobird. =
 _Megalancosaurus_, for all intent and purpose, had two thumbs and three=
 fingers, similar to the hand in a true chameleon (see Renesto's=
 aforementioned paper in _JVP_).

        Not having seen either the material for _Protoavis_ or seen a=
 detailed description of their nature, and judging by the photo in=
 Chatterjee's first paper, the metacarpals are quite different from those in=
 _Megalancosaurus_.  I don't think that metcarpals in dinosaur hands were=
 that moveable -- that is, they couldn't be spread well apart from each=
 other, whereas they're quite spread apart in _Megalancosaurus_. =20

        While _Megalancosaurus_ is not classified as an archosaur despite=
 the presence of an antorbital fenestra in Renesto's paper (based, it says,=
 on a cladistic matrix from Benton, which I don't have handy), he does say=
 that it is a node above lepidosaurs....but two nodes below the proper=
 Archosauria, where _Protoavis_, whatever it is, would be located.


Jerry D. Harris
Denver Museum of Natural History
2001 Colorado Blvd.
Denver, CO  80205
(303) 370-6403
Internet:  jdharris@teal.csn.net
CompuServe:  73132,3372

--)::)>   '''''''''''''/O\'''''''''''`  Jpq--   =3Do}\   w---^/^\^o

Overheard in the Denver Museum's=20
old Fossil Mammal Hall, from a mother=20
to her daugher:

"See there?  That's the camel-dinosaur, and=20
the horse-dinosaur, and the elephant-dinosaur..."

--)::)>   '''''''''''''/O\'''''''''''`  Jpq--   =3Do}\   w---^/^\^o