T-Rex Jaw Fragment, with Tooth Grooves!

[rkfrace]

Hello.  A while ago I purchased this specimen from a highly reputable and established seller.  It's a T-Rex jaw fragment from Lance Creek, Wyoming, and was a surface find (see photos of the original specimen in situ; according to the finder, "the piece in question is at the very bottom left,  on top of the edge of the longer bigger bone; the tooth grooves are face-down.").   

 

I'm reaching out to Fossil Forum for guidance along the following lines:  

 

1)  What part of the jaw is this most likely from?  I've been studying images on-line at a cursory level, but I can't find the distinction convex part of the bone that my specimen has (the part that sticks out like a thin ridge).   Any thoughts or, even better, photos of comparable specimens?  

 

2) I trust the original seller, but since it was not found as part of a larger Rex specimen, I figured I'd ask for your confirmation: is this almost certainly a T-Rex?  I'm fairly knowledgeable regarding teeth, but not mandibles.  

 

Thank you all very much in advance; any insight would be deeply appreciated.  

 

With best regards and gratitude, 

  Ryan