"Long before it's in the papers"
July 23, 2015

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Four-legged snake fossil reported found in plain sight

July 23, 2015
Courtesy of the University of Portsmouth
and World Science staff

Sci­en­tists say they have dis­cov­ered the first known fos­sil of a four-leg­ged snake—sit­ting in plain view in a mu­se­um, where no one had re­al­ized its sig­nif­i­cance be­fore.

The ob­ject could help re­veal how snakes, which e­volved from liz­ards, lost their legs, said the re­searchers, one of whom called it seem­ingly “too good to be true” but re­al none­the­less.

Photo of the skeleton (Courtesy U. of Portsmouth)


The find­ings are de­scribed Ju­ly 23 in the re­search jour­nal Sci­ence.

Re­search­er Dave Mar­till from the U­ni­ver­si­ty of Ports­mouth in the U.K. sa­id he found the fos­sil dur­ing a field trip with stu­dents to Mu­se­um Soln­hofen, Ger­ma­ny, which is well known for fos­sils.

The ob­ject “was part of a larg­er ex­hi­bi­tion of fos­sils from the Cre­ta­ceous pe­ri­od,” the last great age of the di­nosaurs, he said. 

“It was clear that no-one had ap­pre­ci­at­ed its im­por­tance, but when I saw it I knew it was an in­cred­i­bly sig­nif­i­cant spec­i­men.”

“It is a per­fect lit­tle snake, ex­cept it has these lit­tle arms and legs, and they have these strange long fin­gers and toes,” sa­id ev­o­lu­tion­ary bi­ol­o­gist Nick Lon­grich of the U­ni­ver­si­ty of Bath in the U.K. 

Lon­grich stud­ied the an­i­mal’s ev­o­lu­tion­ary re­la­tion­ships as part of the re­search ef­fort with Mar­till, who told him of the find o­ver a pint of beer at a pub in Bath. Lon­grich sa­id was skep­ti­cal—un­til he saw pho­tographs.

“A four-leg­ged snake seemed fan­tas­tic and as an ev­o­lu­tion­ary bi­ol­o­gist, just too good to be true, it was es­pe­cial­ly in­ter­est­ing that it was put on dis­play in a mu­se­um where an­y­one could see it,” Lon­grich sa­id.

Photo of the snake's "hands" (Courtesy U. of Portsmouth)


“It is gen­er­al­ly ac­cept­ed that snakes e­volved from liz­ard­s,” Mar­till sa­id. What’s un­clear, he added, is when, why—and what type of liz­ard. “This fos­sil an­swers some ver­y im­por­tant ques­tion­s,” he said. “For ex­am­ple it now seems clear to us that snakes e­volved from bur­row­ing liz­ards, not from ma­rine liz­ards.”

The fos­sil, from Bra­zil, is 110 mil­lion years old, mak­ing it the old­est de­fin­i­tive snake, Mar­till and col­leagues said. Mar­till worked with Lon­grich and Ger­man pa­le­on­tol­ogist Hel­mut Tisch­ling­er, who pre­pared and pho­tographed the fos­sil.

The snake, named Tetra­po­do­phis am­plec­tus by the team, is a ju­ve­nile and ver­y small, meas­ur­ing just 20 cm (8 inches) long, al­though it may have grown much larg­er. The head is the size of an a­dult fin­ger­nail, and the small­est tail bone is on­ly a quar­ter of a mil­li­me­ter long. 

And there are two sets of legs.

The front legs are ver­y small, a­bout 1 cm long, but have lit­tle el­bows and wrists and hands meas­ured at just 5 mil­li­me­ters long. The back legs are slight­ly long­er and the feet are larg­er than the hands and could have been used to grasp its prey, the sci­en­tists said.

“The hands and feet are ver­y spe­cial­ized for grasp­ing,” Lon­grich said. “So when snakes stopped walk­ing and started slith­er­ing, the legs did­n’t just be­come use­less lit­tle ves­tiges—they started us­ing them for some­thing else. We’re not en­tire­ly sure what that would be, but they may have been used for grasp­ing prey, or per­haps mates.”

Artist's recon­struc­tion of Tetra­pho­do­phis eat­ing an olin­da­la­cer­ta (sa­la­man­der) (Cre­dit: James Brown/UOP)


In­ter­est­ing­ly, the re­searchers sa­id, the fos­silized snake al­so has the re­mains of its last meal in its guts, in­clud­ing some frag­ments of bone. The prey was prob­a­bly a sal­a­man­der, show­ing that snakes were car­niv­o­rous much ear­li­er than pre­vi­ously be­lieved.

“The pres­er­va­tion of the lit­tle snake is ab­so­lute­ly ex­quis­ite. The skel­e­ton is ful­ly ar­tic­u­lat­e. De­tails of the bones are clear­ly vis­i­ble and im­pres­sions of soft tis­sues such as scales and the tra­che­a are pre­served,” Tisch­ling­er said.

Sev­er­al fea­tures prompted the clas­si­fi­ca­tion as a snake, rath­er than a liz­ard: it has a long body, not a long tail; the tooth im­plan­ta­tion, the di­rec­tion of the teeth, and the pat­tern of the teeth and the bones of the low­er jaw are all snake-like; and there are hints of a sin­gle row of bel­ly scales, a sure way to tell a snake from a liz­ard.

Tetrapodophis would have lived on the bank of a salt lake, in an ar­id scrub en­vi­ron­ment, sur­rounded by suc­cu­lent plants, the in­ves­ti­ga­tors said. It would prob­a­bly have fed on small am­phib­ians and liz­ards, try­ing to a­void the di­nosaurs and pterosaurs that lurked.

At the time, South A­mer­i­ca was joined to Af­ri­ca as part of a “su­per­con­ti­nent” called Gond­wa­na. The fos­sil’s pres­ence in Gond­wa­na, the sci­en­tists sa­id, sug­gests snakes may have first e­volved there, on­ly be­com­ing wide­spread much more re­cent­ly.


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Scientists say they have discovered the first known fossil of a four-legged snake—sitting in plain view in a museum, where no one had realized its significance before. The object could help reveal how snakes, which evolved from lizards, lost their legs, said the researchers, one of whom called it seemingly “too good to be true” but real nonetheless. The findings are described July 23 in the research journal Science. Researcher Dave Martill from the University of Portsmouth in the U.K. said he found the fossil during a field trip with students to Museum Solnhofen, Germany, which is well known for fossils. The object “was part of a larger exhibition of fossils from the Cretaceous period,” the last great age of the dinosaurs, he said. “It was clear that no-one had appreciated its importance, but when I saw it I knew it was an incredibly significant specimen.” “It is a perfect little snake, except it has these little arms and legs, and they have these strange long fingers and toes,” said evolutionary biologist Nick Longrich from the University of Bath in the U.K. Longrich studied the animal’s evolutionary relationships as part of the research effort with Martill, who told him of the find over a pint of beer at a pub in Bath. Longrich said was skeptical—until he saw photographs. “A four-legged snake seemed fantastic and as an evolutionary biologist, just too good to be true, it was especially interesting that it was put on display in a museum where anyone could see it,” Longrich said. “It is generally accepted that snakes evolved from lizards,” Martill said. What’s unclear, he added, is when, why—and what type of lizard. “This fossil answers some very important questions,” he said. “For example it now seems clear to us that snakes evolved from burrowing lizards, not from marine lizards.” The fossil, from Brazil, is 110 million years old, making it the oldest definitive snake, Martill and colleagues said. Martill worked with Longrich and German paleontologist Helmut Tischlinger, who prepared and photographed the fossil. The snake, named Tetrapodophis amplectus by the team, is a juvenile and very small, measuring just 20 cm (8 inches) long, although it may have grown much larger. The head is the size of an adult fingernail, and the smallest tail bone is only a quarter of a millimeter long. And there are two sets of legs. The front legs are very small, about 1 cm long, but have little elbows and wrists and hands measured at just 5 millimeters long. The back legs are slightly longer and the feet are larger than the hands and could have been used to grasp its prey, the scientists said. “The hands and feet are very specialized for grasping,” Longrich said. “So when snakes stopped walking and started slithering, the legs didn’t just become useless little vestiges—they started using them for something else. We’re not entirely sure what that would be, but they may have been used for grasping prey, or perhaps mates.” Interestingly, the researchers said, the fossilized snake also has the remains of its last meal in its guts, including some fragments of bone. The prey was probably a salamander, showing that snakes were carnivorous much earlier in evolutionary history than previously believed. “The preservation of the little snake is absolutely exquisite. The skeleton is fully articulated. Details of the bones are clearly visible and impressions of soft tissues such as scales and the trachea are preserved,” Tischlinger said. Several features prompted the classification as a snake, rather than a lizard: it has a long body, not a long tail; the tooth implantation, the direction of the teeth, and the pattern of the teeth and the bones of the lower jaw are all snake-like; and there are hints of a single row of belly scales, a sure way to tell a snake from a lizard. Tetrapodophis would have lived on the bank of a salt lake, in an arid scrub environment, surrounded by succulent plants, the investigators said. It would probably have fed on small amphibians and lizards, trying to avoid the dinosaurs and pterosaurs that lurked. At the time, South America was joined to Africa as part of a “supercontinent” called Gondwana. The fossil’s presence in Gondwana, the scientists said, suggests snakes may have first evolved there, only becoming widespread much more recently.