What features separate legless lizards from snakes, despite superficial resemblance?
Answer
Movable eyelids and external ear openings
The primary anatomical features that confirm a limbless reptile is technically a lizard rather than a snake relate to sensory apparatus. Lizards, even those that have evolved serpentine bodies resembling snakes (like the slow-worm), retain movable eyelids, which allow them to blink and protect the eye surface. Additionally, lizards generally possess visible external ear openings, known as tympanums, on the sides of their heads. Snakes lack both these movable eyelids and external auditory structures, making their presence definitive proof of lizard classification despite the loss of limbs.
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