Question

Snakes do not have legs because

• A. Legs were lost during their entry in tunnels.
• B. Legs were lost during evolution.
• C. The ancestors of reptiles did not have legs.
• D. There are no legs in lizards.

Answer 1

The correct option is B Legs were lost during evolution.

According to the fossil records, snakes used to have a complete set of forelimbs and hindlimbs about 150 million years ago. The gene that signals the limbs development in snakes is the Sonic hedgehog gene. According to a recent study, a trio of mutations occurred in this gene about 100 million years ago and thus making it less likely to expressed. So, the mutations made the gene to be eradicated completely and hence, the snakes don't have limbs or legs.

Hence, the present day limbless snakes with long slender body developed from the limbed ancestors. Also, due to continued disuse of limbs and stretching of their body to suit their creeping mode of locomotion, legs were lost during the course of evolution.

So, the correct answer is B.