protoconules

Protoconules are small, accessory cusps found on the occlusal (chewing) surface of mammalian teeth, particularly molars. They are considered an early developmental feature and are most prominent in primitive or ancestral forms of mammals. The term itself is derived from "proto," meaning first or early, and "conule," a diminutive of cusp. These structures are typically located lingual to the paracone and metacone of a molar, and their presence and size can vary significantly between different species and even within different lineages.

In some extinct mammals, protoconules were well-developed and played a role in mastication. As mammalian evolution progressed, many groups either reduced or lost their protoconules entirely, with the main cusps becoming more dominant. The study of protoconules is important in paleontology for understanding evolutionary relationships among mammals. Their presence or absence, along with their specific morphology, can help identify fossil specimens and reconstruct phylogenetic trees. They are often observed in early ungulates, artiodactyls, and perissodactyls, and their gradual reduction is a notable trend in the evolution of these groups.