Post Oak Creek Shark Teeth

[GPayton]

I've only been able to make it out to Post Oak Creek in Sherman, Texas once before, but I was fortunate enough to be able to spend an entire day shoveling and sifting and managed to come away with a decent haul of mostly complete shark teeth. Most of what I found was pretty easily identifiable, but I've held on to the three teeth that I found that day that continue to make an ID difficult despite how (mostly) complete they are. 

The first tooth I'm also certain is a Protolamna. It has the characteristic longitudinal ridges on both sides, the dental band on the front, and the cusplets are connected to the main blade. 

The other two teeth I have no idea where to begin. The one in the middle may simply be too worn to attempt a concrete ID, as the enamel closest to the root (which would be one of the most diagnostic features) has been eroded away. I initially thought the third tooth might be Cretoxyrhina, but I can't determine whether the root looks the way it does as a result of erosion or if it's still retained most of its original shape. If the latter, then it doesn't resemble any Cretaceous shark tooth I've found before. 

As I know the creek has been much more heavily hunted by other Texas members of the forum than myself, I've got my fingers crossed somebody should be able to help me out. Any advice is appreciated!