Here is a fossil tooth I recently acquired, from a Spinosaurus, which is likely the largest carnivorous dinosaur, if not the largest land predator, that ever lived. It's somewhat difficult to say for certain as a complete skeleton has never been found (only scanty partial specimens). They have prominent dorsal neural spines for which various theories have been proposed. Some people think they were used for thermal regulation, others for sexual display, others to show aggression and dominance. It could also have been a hump. Regardless, this is one of the larger fossil teeth I own and one of my favorite specimens.
Kem Kem Beds, Morocco
70 million years old