Since they first appeared during the age of the dinosaurs, snakes have been "writing" the story of evolutionary success, crawling to almost every corner of the Earth - from the oceans to the tops of trees.

New research details how these legless reptiles, which evolved from four-legged lizards, gained an edge over the competition, reports BTA. 

Scientists have created a complete evolutionary tree of snakes and lizards using genomic data spanning about 1,000 species.

At the same time, they reviewed the fossil record and gathered data on the snakes' diet, skull anatomy, reproductive biology and geographic range.

The researchers found that snakes experienced a "boom" of innovation early in their history and evolved at a rate possibly three to five times faster than their lizard cousins.

Snake skulls show how they adapt to their prey

"It's like lizards traveling through time on an evolutionary moped or go-kart, and snakes being V12 Lamborghinis. Lizards ride the city bus. Snakes ride the evolutionary bullet train," says University of Michigan evolutionary biologist Daniel Rabosky. , lead author of the study published in the journal Science. 

Snakes appeared about 120 million years ago.

Early snakes had rudimentary limbs, with the oldest known fully legless snake living about 85 million years ago, according to George Washington University evolutionary biologist and study co-author Alexander Piron.

Early snakes changed their anatomy in important ways, mostly to become highly specialized predators, the study shows.

Their skulls become extremely flexible to better capture and swallow prey.

Snakes acquire an impressive system for detecting prey, as their sense of smell, or chemoreception, improves.

Some of them develop the ability to see infrared, essentially becoming heat sensors.

Others become poisonous.

Researchers have collected a large body of data on the diet of snakes and lizards, including valuable information on the stomach contents of dead specimens from museum collections.

"Lizards usually feed on insects and spiders and things like that, sometimes on plants. Snakes are really extreme specialist feeders and usually eat vertebrates or weird, hard-to-eat invertebrates. When snakes feed on invertebrates, they often ingest dangerous things like poisonous centipedes and scorpions, slimy harmful snails or slugs," says Rabosky.

Various groups of lizards have become legless over time, but have never experienced the same evolutionary prosperity as snakes.

"Snakes are very different from other legless lizards. Most such lizards burrow in sand or soil, or perhaps crawl in grass. Snakes do everything from deep diving into coral reefs in the ocean to super-fast tree climbing and everything in between them," adds Raboski.

A burst of evolutionary innovation in snakes occurred about 90-110 million years ago, and again at different times after the asteroid impact 66 million years ago that doomed the dinosaurs, Pyron explains.

According to the scientists, snakes were very good at innovation - at rapidly developing new traits, and were able to take advantage of ecological opportunities that arose, such as when the mass extinction 66 million years ago wiped out many other species.

The smallest extant snakes are the narrowmouths, which are about 10 centimeters long.

The longest is the reticulated python - about 6 meters.

The largest known extinct snake was Titanoboa, which was about 13 meters long.

Scientists also note that the ecological diversity of the 3,900 existing species of snakes is enormous.

Some people fear and hate snakes, but not the authors of this study.

"Everything about them is fascinating, from the way they move to the way they interact with the rest of the ecosystem. They're beautiful, graceful and mostly harmless," says Pyron. 

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