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How Snakes Have Evolved Through History

Mamba, Pythons

Snakes have been on this planet for millions of years, and might be the most adapted of the reptiles. We don’t really know that much about how they developed throughout the years (their skeletons are very fragile, so fossil records are limited), but they probably appeared around the time of dinosaurs, and descent from lizard ancestors alike the monitor lizard. One of the oldest snake skeleton was found in the Saharan Desert, and dates back to 130 million years ago.

The snake’s ancestors was presumably aquatic at first, but then they got the advantage that their eggs could be laid on the ground thus making it possible for them to survive on land. A process over millions of years caused them to become burrowers, and this is probably when they lost their legs and external ear, making them well adapted for burrowing. Their eyelids were replaced with a clear scale, to protect them while digging. However, some biologists believe that this happened while they were still aquatic, so there is some controversy about this.

Millions of years later some of these creatures emerged to the surface, and the snake as we know it today was born. These snakes were in the boidae group, today’s pythons and boas, making these snakes the most primitive snake alive today. In fact, pythons still have remains of their hind legs, called spurs that stick out at the base of their tail. The boidaes have no venom, but use constriction to kill their prey.

Around 40 million years ago, smaller snakes appeared who had developed further, adapted to new areas and created new characteristics, and these snakes became members of the colubrid group, which is the biggest snake group today. Colubrids are some of the snakes that are referred to as “New World” snakes. One member of this family is the corn snake!

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At first the snake world was greatly dominated by the boidae, the colubrids were not able to take over the areas of the much bigger python and boa. Then the world went through a dramatic change, the temperatures got cooler, greatly reducing the number of boidaes. They could not survive in the cooler temperatures, which enabled the colubrids to spread over large areas, as they got to be more temperature and climate tolerant then the boidaes.

The boidaes(python and boa) were now limited only to the parts of the world with high temperatures, while the colubrids could survive almost everywhere. Not surprisingly the number of colubrids greatly increased, and they spread all over the world.

Over time some of the colubrids developed rear fangs. In rear fanged snakes, their fangs are at the back of their mouths making the venom not intended as the only weapon against prey, but rather as an aid in addition to constriction. Many people keep rear fanged snakes as pets(for example the hognose and gardener snake), as it is rarely you get venom injection from them; you would have to get your hand all the way inside their mouths for the snake to inject it.

Just to make one thing clear in case of misunderstanding, the corn snake (as well as the milk snake and the king snake) are NOT rear fanged. They have no venom whatsoever.

After some of the colubrids developed rear fangs, another group emerged which has been called Elapids. I only have to say mamba to make it obvious that this group of snakes uses their venom as their main defense and attack. The elapids have short fangs in their upper jaw that can inject poison, and the fangs are hollow and get its poison from the venom gland in the snake’s cheek. The elapids injects venom much more efficiently than the rear fanged snakes. Other members of this group are cobras, sea snakes, taipans and adders. Their fangs is basically what distinguishes this group from the colubrids, as they are otherwise very much alike.

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The snakes evolved even further, a few million years ago the group vipers began developing. Their fangs are a lot longer then the elapids. The group get its name because most of the vipers are ovoviviparous, they give birth to live babies(not eggs). In latin “vivo” = “I live”, and “pario” = “I give birth”. The rattle snake, probably the most “advanced” snake alive today, evolved from the vipers to get un-shed skin at the end of its tail that it can use to warn predators.

To conclude the snake’s history; they developed from a monitor lizard, went through a phase of burrowing, came up to the surface leg- and earless, then developed into different groups, each with their own characteristics. Seeing as the snakes have been here since the dinosaurs, and are still thriving all over the world(exept the arctic region), snakes are one of the most adaptable and succesful creature there is.