Britannica Sources used in this answer

Why do many herbivores have continuously growing incisors or cheek teeth?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Two wild horses graze on tall grass in the open prairie of Theodore Roosevelt National Park, with rolling badlands visible in the background. — Feeding behaviour Wild horses graze in the Badlands of North Dakota.

Many herbivores possess continuously growing incisors or cheek teeth as an evolutionary adaptation to circumvent the problem of tooth wear caused by their specialized diets.1

Because herbivorous feeding often involves grinding tough plant material, these animals face significant dental attrition. To maintain functionality throughout their lives, many herbivorous groups—including rodents, lagomorphs, and various ungulates—have evolved rootless teeth with open pulp cavities. This anatomical feature allows for continual growth, ensuring that the teeth are replenished as the surfaces are worn down by constant use.1

In addition to this continuous growth, some herbivores have evolved high-crowned teeth, known as hypsodont teeth, which are further strengthened by deposits of secondary cement to increase their resistance to wear. These dental specializations allow herbivores to effectively process abrasive vegetation over long periods.21