The diversity of modern snakes appeared during the Paleocene epoch ( c. 66 to 56 Ma ago, after the Cretaceous–Paleogene extinction event).
Their results suggest that snakes originated on land, rather than in water, during the middle Early Cretaceous period (around 128.5 million years ago), and most likely came from the ancient supercontinent of Laurasia. This period coincides with the rapid appearance of many species of mammals and birds on Earth.
Scientists now know that snakes — animals distinguished by a hinged jaw — were evolving their elongated bodies and flexible jaws at least 167 million years ago, but still had small legs. Until this latest discovery, the fossil record shows snakes appearing in large numbers only about 100 million years ago.
A century of anatomical and phylogenetic studies have established that snakes evolved from lizards1,2, these two groups forming together one of the most-specious clades of terrestrial vertebrates—the squamate reptiles.
Today, the prevailing view is that snakes evolved from an as-yet-unidentified land-dwelling (and probably burrowing) lizard of the early Cretaceous period, most likely a type of lizard known as a "varanid." Today, varanids are represented by monitor lizards (genus Varanus), the largest living lizards on earth.
Comparisons between CT scans of the fossil and modern reptiles suggest that snakes lost their legs when their ancestors evolved to live and hunt in burrows, habitats in which many snakes still live today. The findings disprove previous theories that snakes lost their legs in order to live in water.
The analyses helped to pinpoint the time that modern snakes evolved. Their results show that all living snakes trace back to just a handful of species that survived the asteroid impact 66 million years ago, the same extinction that wiped out the dinosaurs.
Found in the early 2000s after 240 million years embedded in the mountains of northern Italy, a fossil known as Megachirella wachtleri has claimed the title of oldest-known species of the reptilian order Squamata, making it an ancestor of all the world's lizards and snakes, as The Washington Post explains.
While the venom system evolved before snakes, it was they who took the rather simple product and gave it a sophisticated upgrade in its potency and variety. "Venom is all about prey capture, so differences in prey result in different venoms being selected by evolutionary pressures," said Fry.
It's thought that snakes lost their legs 100 to 150 million years ago, but debate is still raging as to whether their limbed ancestors were aquatic or terrestrial. The evolution of a long, legless body could be beneficial to life underwater as it would enable eel-like swimming.
Lesson Summary. Reptiles have closed circulatory systems and either three or four-chambered hearts. Most reptiles have three-chambered hearts, except for the crocodilians (alligators, crocodiles, and caiman), which have four-chambered hearts.
Agnathans, or jawless fish were the earliest fish and the first true vertebrates and they appeared around 480 million years ago.
A new study of the monkey brain suggests that primates are uniquely adapted to recognize the features of this slithering threat and react in a flash. The results lend support to a controversial hypothesis: that primates as we know them would never have evolved without snakes.
New research suggests humans have evolved an innate tendency to sense snakes — and spiders, too — and to learn to fear them. Fear of snakes is one of the most common phobias, yet many people have never seen a snake in person.
But scientists say a handful of surviving snake species were able to thrive in a post-apocalyptic world by hiding underground and going long periods without food. The resilient reptiles then spread out across the globe, evolving into the 3,000 or more species known today.
Isbell's work is detailed in the July issue of the Journal of Human Evolution. Fossil and DNA evidence suggests that the snakes were already around when the first mammals evolved some 100 million years ago. The reptiles were thus among the first serious predators mammals faced.
Slow lorises are one of the world's only venomous mammals. Even rarer, they use their venom on one another.
The now-infamous ending plot twist reveals that Venom Snake is simply a "clone" of Big Boss, a double created to distract the world while the real Big Boss betrays his allegiances to build Outer Heaven.
Another hypothesis is that the spider venom system evolved from the silk-producing glands present in early chelicerates. In sea spiders, the larvae of some species possess secretory silk glands in their chelae (Bogomolova, 2007), which may have been repurposed as venom glands in spiders.
Titanoboa, discovered by Museum scientists, was the largest snake that ever lived. Estimated up to 50 feet long and 3 feet wide, this snake was the top predator in the world's first tropical rainforest.
The remains of the oldest recorded snake, aged 167 million years ago, were found in Southern England. The 60-million-year-old Titanboa was the largest snake to ever exist, growing up to 50 feet long and weighing up to 2,500 pounds.
We know from their shared anatomy that snakes evolved from lizards. We also know that the skulls of snakes have been key to their successful and highly specialized feeding adaptations.
In fact, birds are commonly thought to be the only animals around today that are direct descendants of dinosaurs. So next time you visit a farm, take a moment to think about it. All those squawking chickens are actually the closest living relatives of the most incredible predator the world has ever known!
Named Titanoboa cerrejonensis by its discoverers, the size of the snake's vertebrae suggest it weighed 1,140 kilograms (2,500 pounds) and measured 13 meters (42.7 feet) nose to tail tip.
Snakes used to wander the Earth on legs about 150 million years ago, before they shifted from strut to slither. Now, two scientists have pinpointed the genetic process that caused snakes to lose their legs.