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Plants came to land 100 million years earlier than previously thought: Study

Tuesday, 20 February 2018 7:03 PM [ Last Update: Tuesday, 20 February 2018 7:14 PM ]

Early life on land resembled cryptogamic ground covers like this lava field in Iceland. The file photo shows Sylvia Pressel (R) as she examines some plants. (Photo by Bristol University)

When life, in plant form, came from seas to barren lands, mountains and hills were rocky crags and lowland plains were dustbowls, and rates of erosion were more than ten times what they are today. As plants further moved onto land, soils developed, and as geological times passed by, soils and plants more and more crept outwards from the seas and increasingly covered the land surface of our cosmic home, giving it familiar shades of green to its continents. But when plants first invaded the land?

Up until now it was commonly believed, based on previous studies, that plants first snuck out of the ancient seas some 420 million years ago, at the end of the Silurian period.

However, a study, whose results were published in the journal Proceedings of the National Academy of Sciences USA on Monday, suggested that plants in fact moved onto land much earlier, during the Series 3 of the Cambrian period, some 500 years ago.

The study, which was conducted by a team of paleontologists at the University of Bristol in the UK, definitely changes perceptions of the evolution of the Earth’s biosphere, pushing the emergence of land life much closer to the Cambrian Explosion, an event that occurred some 541 million years ago, and during which most major water-based animal phyla appeared in the fossil record.

“The team used ‘molecular clock’ methodology, which combined evidence on the genetic differences between living species and fossil constraints on the age of their shared ancestors, to establish an evolutionary timescale that sees through the gaps in the fossil record,” said a statement from the University of Bristol.

For decades biologists have been trying to determine a reliable birth date for land plants. Lacking backbones and hard shells, plants leave relatively little behind in the fossil record, so researchers suspect even the oldest plant fossils do not represent the first flora.

“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-lead author Dr. Mark Puttick, also from the University of Bristol.