Fossils suggest earliest land plants were 472 million years old

Wednesday, October 13, 2010

LONDON - Fossils of the oldest plants ever to colonise land have been found in Argentina, claim scientists.

The new find puts back by 10 million years the colonisation of land by plants, and suggests that a diversity of land plants had evolved by 472 million years ago.

The discovery of the oldest known land plants was made by a team of researchers led by Claudia Rubinstein of the Department of Palaeontology at the Argentine Institute of Snow, Ice and Environmental Research in Mendoza, Argentina.

Scientists say that the newly found plants are liverworts, very simple plants that lack stems or roots.

That confirms liverworts are likely to be the ancestors of all land plants.

The appearance of plants that live on land is among the most important evolutionary breakthroughs in Earth’s history.

Land plants changed climates around the globe, altered soils and allowed all other multi-cellular life to evolve and invade almost all of the continental land masses.

Rubinstein and her collected samples of sediment from the Rio Capillas, in the Sierras Subandinas in the Central Andean Basin of northwest Argentina.

They then processed the sediment samples by dissolving them in strong acids, taking great care to avoid contamination.

In the sediment the team found hardy fossilised spores from five different types of liverwort, a primitive type of plant thought to have evolved from freshwater multi-cellular green algae.

“Spores of liverworts are very simple and are called cryptospores. The cryptospores that we describe are the earliest to date,” the BBC quoted Rubinstein as saying.

These spores, dating from between 473 and 471 million years ago, come from plants belonging to five different genera - groups of species.

“That shows plants had already begun to diversify, meaning they must have colonised land earlier than our dated samples,” said Rubinstein, who made the discovery with scientists at the National University of Cordoba, Argentina and the University of Liege, Belgium.

The study appears in the journal the New Phytologist. (ANI)

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