FOSSILS of a creature that pioneered life on land 365 million years ago have been discovered
in America, it is announced today.
The find, made by researchers from The Academy of Natural Sciences in Philadelphia and
the University of Pennsylvania, is new evidence of the monumental event when our ancestors moved from water to land.
The metre-long remains of the amphibian Hynerpeton bassetti were found in Clinton County,
Pennsylvania, which was once a tropical marshland. The find includes skull fragments and a
well-developed shoulder.
"If there is a single bone that tells a lot about these animals, it is the shoulder," said Professor
Neil Shubin of the university.
Mr Ted Daeschler, of the academy, explained that a strong forelimb was only needed if the
animal spent time out of the water and had to support its own weight.
"This animal could do push-ups,' he said. "The forelimb was very well developed. The earliest
amphibians are the link between fish and all other back-boned animals."
The fossils pre-date the dinosaurs by 140 million years and belong to the oldest amphibian
ever found in North America, a few million years younger than one discovered in Scotland,
at Scat Craig, near Elgin.
The find, reported in Science, raises new questions. Did the earliest amphibians evolve quickly to exploit new opportunities or are there simply gaps in the fossil record that would show a slow, gradual evolution of the specialised features found in Hynerpeton?
And why did some animals adapt to life on land while others stayed in the water?
Current theory suggests that legs were first a way to move about in shallow water and lungs
evolved because the water was depleted of oxygen.
Perhaps the land, already colonised by plants and insects, proved a tempting source of food.
Or maybe amphibians developed strong limbs to escape predators in the water.
