Trex or nano

[Sergiorex]

Found in hell creek fm

[Sergiorex]

Not very robust but doesn’t have the pinches on the bottom

[hadrosauridae]

You're right, it seems to really be in the middle ground.  Looks to have a lot of wear to it also.  Can you get a density count on the serrations?  

 

MY initial reaction is that its a small T.rex rather than nanno, but I'm not an expert.  

[FB003]

Measurements help as well. Looks nano to me though.

[Sergiorex]

It’s not mines, but here’s all the pictures the seller posted. Sorry if it doesn’t help with the id

[Troodon]

It's a Tyrannosaurid tooth.  Do you have a locality where it was found?

[Sergiorex]

Nothing besides hell creek form South Dakota. 

[Troodon]

Okay that's adequate for HC. I'm not willing to make a specific call on this tooth other than indeterminate tyrannosaurid.  The preservation is very poor and since it's not very robust and missing a portion of the lower portion some characteristics may not be seen.

[Dino Dad 81]

I bet that chip on the base would give it the less compressed look of Rex if it were there--too bad it isn't