Surangular

The surangular or suprangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge,^[1] it is connected to all other jaw bones: dentary, angular, splenial and articular.^{[citation needed]} It is often a muscle attachment site. It has been noted in dinosaurs.^[2]

Skull diagram of the dinosaur Proceratosaurus, showing location of surangular

Skull and jaws diagram of the primitive synapsid Dimetrodon, showing location of surangular