Reptile, vertebrate.

Or reptile, reptile, belonging to the tetrapod class Amniotes, a generic term for all species of Sauropods and Synapsids except birds and mammals, including turtles, snakes, lizards, crocodiles, and extinct dinosaurs and mammal-like reptiles, among others.

Skeletal system

The skeletal system of reptiles consists mostly of hard bone, which is highly ossified, with little cartilage remaining.

Most reptiles lack secondary jaws, so when they feed, they cannot breathe at the same time. Crocodiles have developed bony secondary jaws that allow them to breathe continuously while semi-submerged into the water and prevent injury to the brain when prey in their mouths struggle. The family Staphylinidae has also evolved bony secondary jaws.