It is probably not possible with a small piece to identify a dinosaur bone to this level. There is a good discussion of this on the fossil forum:
http://www.thefossilforum.com/index.php?/topic/38748-could-this-be-real-t-rex-bone/
My only direct experience with dinosaur bones was on a tour of the Gobi desert. We were told if you licked a rock and it stuck to your lip it was a dinosaur bone, if not it was a stone. So we spent the afternoon in the desert licking stones.
Jim