Snakes With Legs? The Curious Case of Snake Evolution!

June 21, 2023 | By Sutirtho Roy
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Snakes have been misrepresented in varying degrees across several myths, folktales and even popular media… but did you know that there’s one amazing narrative we have all overlooked?

From slithering on the ground in the age of dinosaurs to living amidst the nooks and crannies of urban jungles and gardens, snakes have stood the test of time. [Photo © Wildlife SOS/ Nikhil Bisht]

It’s the story of their evolution! To know how these reptiles evolved, we need to turn to the right storytellers – their fossils. Snakes form one of the major groups within reptiles alive today, accompanied by lizards, crocodiles and turtles. However, despite being (in)famous, evolution of snakes is least studied. 

This is because the ancestors of snakes had bodies that were even more fragile, and therefore, their preserved remains, or fossils, are few. Most fossils that have lasted over time contain incomplete elements to conduct conclusive studies. These petrified remains of extinct species are all scientists have to understand how the animal evolved. Because of such lack of evidence, the nature of their studies also lean a lot on speculation. 

Losing the Legs

Did you know that snakes evolved from a family of lizards? [Photo © Wildlife SOS/Nikhil Bisht]

It is widely believed that snakes evolved from lizards belonging to the Varanidae family. Today, varanids are represented by monitor lizards, making them the closest living relatives to snakes. Over time, the descendants of these prehistoric varanids began losing their legs, giving rise to several transitional forms between snakes and lizards.

Through fossil studies, palaeontologists have been able to point out four such extinct genera of snakes, namely Eupodophis, Haasiophis, Pachyrhachis and Najash. All species under them had stubby, vestigial hindlimbs. These earliest forms of snakes date back to ancient times and are commonly referred to as proto-snakes.

Proto-snakes underwent a long journey before they evolved into sleek, legless snakes that we see today. [Infographic © Wildlife SOS/Avni Gupta]

Scientists believe that Eupodophis was a marine proto-snake. Along with Hassiophis and Pachyrhachis, its fossils were located in the Middle East whereas the remains of Najash were found in South America. 

This proves that these unique reptiles were already diversifying in different ecological niches and geographical locations even before losing their limbs. These reptiles coexisted with dinosaurs during the geologic period of the Cretaceous. However, it was only after the dinosaurs went extinct that they truly came into their own.

The Indian rock python is a constrictor, it wraps itself around its prey and squeezes it to death before devouring it whole. [Photo © Wildlife SOS/ Shresatha Pachori]

Death by Venom and Suffocation

Today, the biggest snakes are represented by the reticulated python and the green anaconda, but neither of them comes close to the largest that the world has known. For a long time, the 33-feet-long Gigantophis from the Eocene epoch was the largest prehistoric snake known to us.

However, this enormous animal would soon have its record broken by the South American Titanoboa, which measured over 50 feet in length. Titanoboa lived on for five million years after the dinosaurs no longer existed, ruling over a land where mammals had yet to grow into large sizes.

Commonly misrepresented snakes of India. [Infographic © Wildlife SOS/Avni Gupta]

It is speculated that both Gigantophis and Titanoboa killed their prey by squeezing them tightly in a process similar to how modern-day pythons and boas coil around their prey to suffocate them. Simultaneously, other groups of snakes were also developing a different hunting tactic – venom.

Venom in both snakes and certain lizards developed to become a specialised version of their saliva. In fact, venom evolved separately among different snake families through a process called convergent evolution. Today, among the 14 different snake families making up the suborder Serpentes, only four families consist of venomous snakes, namely:

  • Viperidae, including vipers and rattlesnakes
  • Elapidae, including sea snakes, cobras, taipans, coral snakes and kraits
  • Colubridae, including the boomslang
  • Atractaspididae, including burrowing asps and purple-glossed snakes

A large part of what gives snakes their bad reputation is their venom. Species like the cobra and viper have entered popular culture and myth as evil entities. Snakes have been depicted as monstrous entities with gross features and unrealistic levels of aggression (Yes, we are talking about the Anaconda franchise).

However, most snake bites occur as a form of defence mechanism or retaliation. Snakes are way more scared of human beings than we are of them – and they have good reason to be!

Wildlife SOS attends several calls regarding rescues from urban areas, one of which included a common sand boa found in the Dwarka region of Delhi. [Photo © Wildlife SOS/Kunal Malhotra]

These reptiles have been evolving over the millennia, adapting to new geographies, diets, climates and even the unique conditions needed to survive in an urban environment. However, rising human-animal conflict, increasing urbanisation and the infamous snake-charming practice have driven many of them to the brink of extinction in India.

Snake Rescues by Wildlife SOS

Over the years, Wildlife SOS has rescued several of these reptiles from distress, including the Big Four of India as well as non-venomous constrictors. Our Rapid Response team operating out of Jammu and Kashmir has even rushed to the aid of elusive, endangered animals like the levantine viper.

Often complicating the nature of rescues is human prejudice. While vipers and cobras receive the worst criticism, the fear of snakes or ophidiophobia does not even spare non-venomous animals. Just last year, a six-foot-long Himalayan trinket snake was a victim of irrational fear after being spotted by the locals in Jammu and Kashmir. People tried to chase the snake away using a sharp object.

This led to an injury on the reptile’s neck. Fortunately, the snake was provided medical treatment due to a timely rescue by our Rapid Response Unit. The Himalayan trinket was released into the wild thereafter.

An injured Himalayan trinket snake was given urgent treatment after fearful locals attacked the snake with a sharp object. [Photo © Wildlife SOS]

Incidents such as this make it abundantly clear that while these reptiles may have persevered through natural transformations over millions of years, they are highly threatened by human-reptile conflict in the present age. While many are saved in rescue operations, widespread awareness is crucial to help sustain reptile species. 

In other words, communication and conservation need to go hand in hand. Over the years, Wildlife SOS has conducted various awareness sessions to guide locals with the correct way to react to snakes in their vicinity.

Furthermore, when performing reptile rescues, we make sure to raise an understanding about the species in the communities. The Wildlife SOS Reptiles group on Facebook encourages open interactions about snakes and engages in myth-busting sessions about these animals. The group highlights our rescue operations, and our efforts towards conserving reptiles have received a positive response by people. Many are now well-informed on how to react when they encounter reptile species.

Due to sensitisation sessions, Wildlife SOS has been able to save several injured or distressed reptiles from urban locations. In April 2023, a spectacled cobra found itself trapped in an open well in Maharashtra. Around the same time, a red sand boa was caught between two tires in Delhi. In both instances, timely calls from concerned citizens ensured that our teams reached the spot to rescue and release the snakes.

An Indian cobra was caught in a perilous situation inside an open well into which a golden jackal had fallen. [Photo © Wildlife SOS/ Akash Dolas]

While looking at the evolution of snakes, we realise how unique and fascinating these reptiles are. Snakes are essential to maintain the balance in our ecosystem. While we spread awareness about them in order to free them from the shackles of mistaken beliefs, we also encourage you not to engage with them directly upon any encounter.

If you see a snake in distress, immediately contact your local animal welfare organisation. You can reach out to our Rapid Response Units on our 24×7 helplines in these cities:

Delhi-NCR: +91-9871963535
Agra, Uttar Pradesh: +91-9917109666
Vadodara, Gujarat: +91-9825011117
Srinagar, Jammu and Kashmir: +91-7006692300/ +91-9419778280

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Hotline Number | हॉटलाइन नंबर

Delhi NCT Region +91-9871963535
Agra Region (UP) +91-9917109666
Vadodra Region +91-9825011117
J&K Region +91 7006692300
+91 9419778280