This tooth is from a family of sharks called Hybodont Sharks. They have many shell crushing teeth. A large shark, up to 10m long.
 
Fossil: Shark Tooth ‘Ptychodus Mortoni ‘
Location: Texas, USA
Age: Cretaceous
Dimensions: 2.2cm x 1.3cm
 
A genuine fossil. You will receive the item pictured.
All measurements are approximate.