Where are the snake legs

Evolution: Why Snakes Lost Their Legs

There are lizards and sneaks and snakes. It was precisely in this order that these reptiles emerged from one another in the course of evolution. When amphibious life left the water some 375 million years ago, four legs were extremely useful. The legs also remained when the amphibians, which were very sensitive to drought, developed into the early reptiles with their scaly, evaporation-resistant skin. That was about 300 million years ago.

But at some point running no longer seemed to be the optimal form of locomotion for all reptiles. Legs were more of a hindrance. Around 100 million years ago, snakes and snakes first lost two and later even all four limbs.

Anyone who visits an exotic store can easily see that this has happened: lizards have legs, snakes do not. Nevertheless, both get along very well in their respective habitats. Modern snakes even belong to extreme artists of movement, not only can they glide over the ground or up a tree trunk at lightning speed.

Some snakes can almost fly

They can swim and some species like the brown tree snake can almost fly. At least, through extreme body mechanics, they can get off a branch two meters away from the next, although they are hardly longer themselves. To do this, they only hold on to the last end of their tail.

In the current issue of the journal “Current Biology”, scientists from Florida have at least solved a herpetology riddle: They were able to show which genes are involved in the fact that some reptiles have legs - and others do not.

Most vertebrates have what is known as the sonic hedgehog gene. In the early embryonic development, it ensures, among other things, that arms and legs, fingers and toes develop. It seems by coincidence that hundreds of millions of years ago three different mutations in the genome of early reptiles occurred. These changes mean that the sonic hedgehog gene is not activated during embryonic development. The switch that ensures that arms and legs grow is not thrown.

Thanks to this lack of limbs, the animals affected were able to optimally occupy certain ecological niches. As fast, silent reptiles, they had an advantage over food competitors - which is why legless snakes have prevailed.

There is no going back

The fact that snakes used to have legs is not only proven by fossil finds, such as that of an ancient snake, which scientists found in the Crato Formation in northeastern Brazil and presented in the journal "Science" last year.

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