They were among the early wave of tetrapods, a group including all land-living vertebrates. The first tetrapods evolved from fish during the Devonian. Until now, it had been thought that this evolution revolution occurred in warm climes because the fossils of all the earliest-known amphibians, as well as their fish forerunners, had been found in places that were tropical or subtropical at the time.
Africa during the Devonian was part of a super-continent called Gondwana that also encompassed South America, India, Australia and Antarctica. The Waterloo Farm site was within the Arctic circle.
Dr Alex Ritchie, palaeontologist, showing how there are still many fish fossils by a quarry near Cowra, NSW, from the Devonian Period in 2013.
Photo: Ben Rushton"So we now know that tetrapods, by the end of the Devonian, lived all over the world, from the tropics to the Antarctic circle," said paleontologist Robert Gess, based at the Albany Museum in Grahamstown as part of the South African Centre of Excellence in Palaeosciences, centered at the University of the Witwatersrand.
"So it's possible that they originated anywhere and that they could have moved onto land anywhere. It really broadens the scope of possibilities," Gess added.
The Waterloo Farm site was a river-mouth environment, a tidal estuary opening onto the sea, and likely had a cold climate akin to northern Norway's Atlantic coast, said paleontologist Per Ahlberg of the University of Uppsala in Sweden.
"There would certainly have been several months of winter darkness, as well as midnight sun in the summer," Ahlberg said, adding that it probably snowed in winter.
The research was published in the journal Science on Friday.
Reuters