Which physical traits distinguish snakes from lizards?

While snakes are considered a highly specialized group of limbless lizards, they are traditionally distinguished from other lizards by several key physical traits.12

The primary physical characteristics that set snakes apart include:

• Limblessness: Unlike most lizards, which possess legs, snakes have a greatly elongated body and tail and lack limbs.13
• Eyelids: Snakes lack movable eyelids, whereas most lizards possess them.13
• Ear Openings: Snakes do not have external ear openings, a feature typically found in most other lizards.13

It is important to note that these distinctions are generalizations. Some non-snake lizard species have lost their limbs, movable eyelids, or external ear openings through evolutionary processes. Furthermore, while snakes lack an external ear, they are not deaf; they possess a specialized internal mechanism involving the quadrate bone that allows them to perceive low-frequency airborne sound waves and ground vibrations.14