How did horse teeth adapt to a diet of grass?

To adapt to a diet of grass, which is significantly coarser than succulent leaves, the teeth of the horse underwent several key evolutionary changes:2

• High-crowned structure: Horses developed hypsodont teeth, which are high-crowned and possess an extremely long crown. Much of this crown is initially buried beneath the gumline; as the grinding surface wears down, the tooth continues to grow out of the jaw, ensuring an adequate grinding surface throughout the animal's life.123
• Increased complexity: The cheek teeth evolved larger, stronger crests and a complicated selenodont surface to facilitate the side-to-side jaw motion necessary for grinding tough grass blades.12
• Cement deposits: The hollows between the ridges (lophs) of these teeth are filled with a deposit of secondary cement, which strengthens the structure and increases resistance to wear.1
• Molarization: Through a process of molarization, the premolars became as large and complex as the molars, resulting in a uniform battery of grinding teeth.1

These specialized adaptations allow horses to efficiently process harsh vegetation.3