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 Scientists on Tuesday described the four oldest-known snake
fossils, the most ancient of which was a roughly 10-inch-long (25
cm) reptile called Eophis underwoodi unearthed in a quarry near
Oxford, England, that lived about 167 million years ago.
The remarkable fossils from Britain, Portugal and the United States
rewrite the history of snake evolution, pushing back snake origins
by tens of millions of years.
Until now, the oldest snake fossil dated from about 102 million
years ago, said University of Alberta paleontologist Michael
Caldwell, who led the study published in the journal Nature
Communications.
Scientists say snakes evolved from lizards, and a number of
previously discovered fossils of primitive snakes featured small
back legs.
Those described on Tuesday did not include entire skeletons, but the
researchers say all four may have had some form of reduced forelimbs
and hind limbs.
 That does not mean they walked. "It seems probable that they were
slithering, so to speak, though the limbs might still have been used
for grasping," Caldwell said.
"Snakes have generated fear and fascination since ancient times,"
said paleontologist Sebastián Apesteguía of Argentina's National
Scientific and Technical Research Council (CONICET) and Universidad
Maimonides, another of the researchers.
"However, we know very little about their very origins," added
Apesteguía, who speculated the first snakes may have appeared about
190 million years ago.
The four snakes lived during the age of dinosaurs. Eophis, the
oldest, was a swamp dweller that probably ate small minnows, insects
and tadpoles.
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The largest, named Portugalophis lignites and discovered in a coal
mine in central Portugal, measured about 4 feet (1.2 meters) and was
155 million years old. It may have eaten small mammals, young
dinosaurs, lizards, birds and frogs.
Diablophis gilmorei, a snake from about 155 million years ago, was
found in western Colorado. It was a bit larger than Eophis and
probably ate similar prey.
Parviraptor estesi, found in sea cliffs near Swanage, England, was
about 2 feet (60 cm) long and 144 million years old.
Caldwell said the four snakes' skull anatomy was similar to modern
snakes and other fossil snakes. Caldwell said the characteristic
snake skull design likely emerged before these reptiles acquired
their elongated and legless body plan.
None of the four was venomous, Caldwell said. The oldest venomous
snake fossils are about 20 million years old.
(Reporting by Will Dunham; Editing by Eric Beech)
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