20 February 2018
A seminal event in the Earth's history - when plants appeared on land - may have happened 100 million years earlier than previously thought.
Land plants evolved from "pond scum" about 500 million years ago, according to new research.
These early moss-like plants greened the continents, creating habitats for land animals.
The study, based on analysing the genes of living plants, overturns theories based purely on fossil plant evidence.
"Land plants emerged on land half a billion years ago, tens of millions of years older than the fossil record alone suggests," said study author, Dr Philip Donoghue of the department of Earth Sciences at the University of Bristol.
"This changes perception of the nature of early terrestrial environments, displacing pond scum in favour of a flora that would have tickled your toes - but not reached much higher. "
Early plants would have provided a habitat for fully terrestrial animals, which emerged onto land at much the same time, he said.
This coincides with the time period when life became more diverse and abundant in the seas - an event known as the Cambrian explosion.
"Our results show the ancestor of land plants was alive in the middle Cambrian Period, which was similar to the age for the first known terrestrial animals," said co-researcher Dr Mark Puttick, from the Natural History Museum, London.