Where do snakes fit in the animal kingdom?
All snakes belong to the class Reptilia alongside lizards, crocodiles, turtles, and lizard-like animals called tuataras, endemic to New Zealand. Snakes and lizards are distinguished from crocodiles, turtles, and tuataras because of their scales. Snakes belong to the order Squamata with lizards, which comes from the Latin squatmatus meaning “having scales.” Furthermore, snakes belong to the suborder Serpentes. Interestingly, the classification of reptiles as a class and the classification of the orders within the class are debated today. Some biologists suggest that the bird class Aves should be dissolved and combined with reptiles. Recent DNA analysis has provided evidence of the close evolutionary relationship between birds and reptiles. For example, crocodiles are more closely related to birds than they are to all other living reptiles! To read more about the origin of birds, click here! To read more about the relationship between crocodilian species and birds, click here!
What is a snake?
So, we know where snakes fit in the animal kingdom; let’s learn more about the snakes themselves. Snakes are scaly, legless, elongated reptiles. They are carnivorous, meaning they eat meat. In fact, snakes have many joints in their skull that allow them to eat prey much larger than their heads. Some species of snakes lay eggs, and some give birth to live young. Also, snakes undergo an interesting process called molting, where they regularly shed a layer of skin. Three thousand nine hundred species of snakes exist around the world on every continent except Antarctica and excluding New Zealand, Greenland, Iceland, and Ireland. Interestingly, one species called the European Viper even inhabits part of the Arctic Circle in northern Europe! To learn more about why there are no snakes in New Zealand, follow this link! Here we will meet the oldest snake ever, a species of snake that was a transitional form descended from lizard ancestors, the largest viper ever, the largest snake ever, and a cool species of extinct blind snake.
Dawn Snake (Eophis underwoodi)
The oldest species of extinct snake that exists in the fossil record is Eophis underwoodi, or colloquially the Dawn Snake. The Dawn Snake was on Earth during the Middle Jurassic epoch, which was during the Jurassic period. The Middle Jurassic is classified as the timeframe from about 174 to 163 million years ago. This species is so old that it survived the asteroid impact that caused the extinction of dinosaurs! The Eophis underwoodi species inhabited modern-day England, but its distribution isn’t entirely understood due to available fossil data. The fossil evidence for which this species was described is a fragment of a lower jawbone found in an English quarry. It is hypothesized that the Dawn Snake retained small legs from its lizard ancestors, was scaly, and had a snake-like head. To learn more about the oldest species of snake and early snake evolution, click here!
Eupodophis descouensi
Eupodophis descouensi is an ancient species of marine snake that was an important transitional form between lizards and limbless snakes. As such, this snake still retained two hind limbs, but the limbs lacked phalange and metatarsal bones and were therefore useless. A trait that is retained from an ancestral species but does not retain its function is called a vestigial structure, like the human tailbone. This species existed approximately 92 million years ago during the Late Cretaceous epoch, much more recently than Eophis underwoodi, but still incredibly long ago! Regarding the physiology of Eupodophis descouensi, many traits are similar to modern reptiles, but there are also several differences. In addition to the primitive hindlimbs, this marine species also had a paddle-like tail that assisted with swimming efficiency. Also, although they lacked metatarsals and phalanges in their hindlimbs, they did retain a femur, tibia, and fibula in each limb. The anatomy of their vestigial limb is actually quite similar to that of extant (living) species of lizards. To learn more about Eupodophis anatomy, click here!
The People’s Snake (Laophis crotaloides)
Laophis crotaloides is an extinct snake of the Viper family. The viper family, Viperidae, contains many species alive today, including pit vipers. Vipers commonly give birth to live young, whereas most other snakes lay eggs. The genus Laophis comes from Ancient Greek, meaning “People’s Snake.” The People’s Snake was found in northern Greece and reached a maximum length of 10-13 feet and a maximum weight of 57 pounds! This incredible weight makes Laophis crotaloides the largest viper yet to be discovered. The largest viper alive today is the Eastern Diamondback rattlesnake which can reach a maximum weight of 35 pounds- a fraction of the size of the ancient People’s Snake! The Laophis crotaloides was temporarily erased from history when its type specimen was lost. A type specimen, or holotype, is the first fossil discovered upon which a new species is based. The People’s Snake was first described in 1857, but when the initial fossil was lost, the species was essentially forgotten until a new fossil was discovered in 2014. To learn more about the rediscovery of Laophis crotaloides, click here!
Titanoboa cerrejonensis
Titanoboa cerrejonensis is the largest extinct snake and the largest snake that has ever lived! This massive snake lived between 60 and 58 million years ago in what is now Colombia and was first described recently in 2009. The Titanoboa could reach a length of 47 feet and a weight of 2,500 pounds! That’s comparable to the weight of a black rhino ( 1,720-3,080 pounds)! The previous record holder for the largest snake ever was held by Gigantophis, approximately 35 ft long. The largest snake alive today is the green anaconda which has a maximum length of about 30 feet and a weight of about 550 pounds- tiny compared to the ancient Titanoboa cerrejonensis! The Titanoboa had unique anatomy aside from its incredible size as well. Interesting features of the snake’s skull suggest that it had a piscivorous (fish-based) diet. It had unique teeth and a palate that appear similar to adaptations observed in many modern snake species. Interestingly, research on Titanoboa has led scientists to believe the climate at the equator during that time was hotter than previously estimated. The limit to an animal’s maximum size is its metabolic rate, which greatly influences thermoregulation (how an animal regulates its body temperature). An animal the size of Titanoboa would not survive in temperatures previously thought to exist at the time and would require a much higher temperature environment. This has caused scientists to reconsider their hypotheses given the new data. Click here to read more about how Titanoboa has affected our understanding of equatorial climate!
Madatyphlops cariei
Another cool species of extinct snake is Madatyphlops cariei, also known as Hoffstetter’s Worm Snake. This smaller snake was about 8 inches. So, if 71 of them were in a line snout to tail, they would be the same length as Titanoboa! Hoffstetter’s WormSnakewas only recently classified as extinct in 1994 by the IUCN list of endangered species. It lived only in an island nation in the Indian Ocean called Mauritius. There are 14 other related species in the genus Madatyphlops that are alive today, primarily living in Madagascar and less commonly on the Comoro Islands. All species of Madatyphlops, like Hoffstetter’s Worm Snake, are blind. In fact, all 278 species in the family Typhlopidae are blind! Hoffstetter’s Worm Snake retained eye-like structures, but they had a negligible function and therefore were considered a vestigial structure, just like the hindlimbs of the Eupodophis species mentioned earlier. Also, unlike most snakes but like most blind snakes, Hoffstetter’s Worm Snake did not have a dislocatable lower jaw, which restricted its diet to organisms smaller than its oral aperture. This snake also had unique physiology evolved for burrowing and low light conditions living underground. To read more about the blind snakes of the family Typhlopidae, click here!
How are extant species of snakes doing today?
Many snake species are “living fossils,” indicating that they have existed in their current form for incredibly long periods with little evolutionary change. Other species are descendants of a long and diverse lineage. All snakes, however, have a very complex and interesting history that scientists are still attempting to demystify in current research.
Additional Information
As we have learned, extinct snakes are incredibly cool animals with many unique and fascinating adaptations. Below are additional links to articles and papers related to snakes.
To learn more generally about snakes, click here!To learn more about the ten most venomous snakes, or the ten largest venomous snakes, click these links!To learn more about the evolution of venomous fangs, click here!To learn about snake bite treatment, click here!To learn more about adaptations in tree-living snakes, click here!To learn more about the use of genomics and the fossil record to understand the origin of snakes, click here!
