Scientists have discovered when the land was covered with the first plants

© Fotolia / euthymiaМорская grass. Archival photoScientists have discovered when the land was covered with the first plants© Fotolia / euthymia

. Paleontologists from the UK found evidence that the first land plants appeared on Earth approximately 500 million years ago, that is, a hundred million years earlier than was given the previous calculations, according to a paper published in the journal PNAS.

«The emergence of plants on the Earth’s surface radically altered its climate and appearance, greatly accelerating the erosion of soil and rocks and dramatically reducing the amount of greenhouse gases in the atmosphere that led to the cold climate and other changes. We showed that it occurred in the middle Cambrian period, at the same time, when the first land animals,» says Jennifer Morris (Jennifer Morris) from the University of Bristol (UK).

Today scientists believe, the first trees appeared in the middle Devonian period, about 400 million years ago. Their appearance has drastically changed the face of the planet, making it «green» by filling its atmosphere a huge amount of oxygen and giving rise to many new species of animals, including ground insects and fungi that feed exclusively on plant biomass.

What looked like these first trees, remains a mystery for paleontologists – it is known only a small number of «petrified forest», a special type of deposits that time, which preserved the full trunks and root systems of these trees trapped underground due to volcanic ash or lava. Their study shows that it was a very bizarre objects, in which the role of the leaves played a special photosynthetic bark, and in appearance they resembled modern dwarf trees of the tundra.

Recently, scientists began to question this idea. For example, two years ago geologists have found evidence that fungi first appeared on land already 440-460 million years ago, and they were unlikely to exist on land by themselves, without the aid of plants or other sources of organic matter, which they had to eat.

Morris and her colleagues has shown that the first primitive plants appeared almost 100 million years earlier than fossils indicate that by combining the fossil record and the genetic tree of evolution the most primitive plants existing on Earth today.

This approach, as the scientists explain, allows to eliminate the main problem that previously prevented and geneticists, and paleontologists to calculate the exact time of occurrence of the plant – the absence of any data by which flora – vascular plants, liver, or true mosses — first appeared on Earth.

Neither genetics nor fossils can’t answer this question alone – it prevents a small subset of known prints of ancient plants, and the DNA comparison speaks in favor of all three variants of the origin of the flora, depending on what sets of primitive plants compared genetics.

When Morris and her colleagues have combined these data, they were able to get an unexpected answer to this question – first to the Ground came the mosses and their close relatives that occurred at about 514-506 million years ago. The first vascular plants, which include all modern and ancient trees, appeared on Earth about 440 million years ago, roughly 40 million years earlier than previously thought.

Such assessments, as the researchers explain, radically change the whole picture of the evolution of life on Earth. First, they say that animals and plants left primary oceanfront Land almost simultaneously and not alternately, as was believed by paleontologists before. Second, this finding indicates that large-scale climate change and his cold has not occurred in the Carboniferous period, in the era of the maximum prosperity of flora, but much earlier.

All this, according to Morris and colleagues, should be considered when exploring how land, flora and fauna influenced the evolution of each other and how their interactions could lead to mass extinctions and other catastrophic events.


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