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Re: T. Rex Arm/Finger Articulation

>I am reading the section in Horner's _The Complete T. Rex_ (paperback
>edition) on the arms and am intrigued by the articulation of the arms
>and the fingers, especially as depicted in the photographs on pp 114-115.
>The "hands" have a kind of "palm-up" appearance. (If you compare
>Gregory Paul's illustration of T. Rex on the cover of The Dinosaur
>Society's recent Dinosaur Encyclopedia, you'll note that Mr. Paul has
>also drawn the hands in a palm-up position, which is a departure from
>the version of the same drawing in his _Predatory Dinosaurs of the World_
>on page 301. Mr. Paul, more than most other dinosaur illustrators,
>conscientiously revises his illustrations as new evidence about dinosaurs

Greg Paul has indeed updated his resorations of theropods with a "palm-in"
orientation (see also the dinosaur article in last year's National
Geographic).  Incidentally, the orientation is properly "palms-in", that is,
the palms facing each other, homologous to the position you hold your hands
in to clap.

>If the palm-up position is the preferred position (as opposed to the more
>familiar palm-down, curled position), is this articulation restricted to
>T. Rex or is it likely the position of other tyrannosaurs, allosaurs,

The "palms-in" condition looks to be a trait of all tetanurines (allosaurs
and coelurosaurs (including tyrannosaurids)).  Birds retain this orientation.

>(If this question has already been addressed in the previous messages
>re: T. Rex's arms, I apologize for bringing it up again.)

Thomas R. HOLTZ
Vertebrate Paleontologist, Dept. of Geology
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)