File:Tyrannosaurus arm bone and flesh.jpg

English: Illustrated diagram of the forelimb in a Tyrannosaurus rex. ( 1 ) First, how the fossil replica look in museum. The bones in the underarm ( radius / ulna )is about 50% of the upper arm ( humerus ). The manus have 2 digits, and is also know to have a third metacarpal ( first found the specimen in "Peck's rex", or MOR 980, in the year 1997 ), which was detached from the manus ( while in specimens of other tyrannosaurids, it was fused with metacarpal II ( take a close look at the hands of Daspletosaurus at http://upload.wikimedia.org/wikipedia/commons/3/36/Daspletosaurus_FMNH.jpg for example) ). In Tyrannosaurus, this bone may acted as attachment for muscles. It also shows traits of possible repeated fractures ( and even in the furcula, see http://dml.cmnh.org/2005Jun/msg00149.html ), which is possible evidence for some type of using of the forelimbs. ( 2 ) Skin added. If we look at Tarbosaurus Bataar, tyrannosaurids had skin with small scales ( see The First Late Cretaceous Footprints from the Nemegt Locality in the Gobi of Mongolia', 2003, Philip J. Currie, Demchig Badamgarav, Eva B. Koppelhus). The claws may had a casing of keratin. The claws also has been shown to face away from each other, rather than to the same direction. Tyrannosaurus arms was strong and sinewy for their size ( calculations indicate they could have lifted about 190 kg, or 426 pound, with each, see http://findarticles.com/p/articles/mi_m1200/is_n2_v138/ai_9222431/ ). They also belive the arms had a limited range of bend, about 40 - 45 degrees.

• This is a alternative version of the deleted image Tyrannosaurus rex arm flesh out.JPG (deleted because the muscles included in the skeletal model in the old illustration was incorrect).