Jan. 8, 2010 The discovery of fossil footprints from early
backboned land animals in Poland leads to the sensational
conclusion that our ancestors left the water at least 18 million
years earlier than previously thought. The results of the
Polish-Swedish collaboration are published online in the journal
Nature. "These results force us to reconsider our whole picture
of the transition from fish to land animals," says Per Ahlberg
of Uppsala University, one of the two leaders of the study. For
nearly eighty years, palaeontologists have been scouring the
planet for fossil bones and skeletons of the earliest land
vertebrates or "tetrapods" -- the ultimate progenitors of all
later amphibians, reptiles, birds and mammals including
ourselves. Their discoveries have suggested that the first
tetrapods evolved relatively rapidly from lobe-finned fishes,
through a short-lived intermediate stage represented by
"elpistostegids" such as Tiktaalik, about 380 million years ago.
But there is another potential source of informa