(ORDO NEWS) — British researchers found out what caused the Devonian extinction, which occurred 359 million years ago. Their article is available on the Science Advances website.
It is argued that the most likely cause of one of the largest extinctions of life in the history of the planet was exposure to ultraviolet radiation. Radiation turned out to be fatal for most living creatures of the Devonian period due to the depletion of the ozone layer caused by global warming – part of the Earth’s natural cycle.
Researchers discovered samples of fossilized plants, presumably from the Devonian period in eastern Greenland and in the Andes, in Bolivia. When dissolving fossils in hydrofluoric acid, scientists were able to isolate the spores of ancient plants. These spores were notable for their unusual shape, especially the shape of their spikes.
According to researchers, the irregular shape of the spores was due to damage to their DNA under the influence of ultraviolet radiation. Also, many of the spore samples found pigmentation, which developed as a protective mechanism against increased levels of ultraviolet radiation.
Radiation has become detrimental to flora and fauna on land and in shallow water. Some plants managed to survive, but the forest ecosystem was undermined. Extinction affected the tetrapods and the dominant group of placoderm fish, the latter being replaced by sharks and bone fish, which managed to survive and maintain a dominant position among the fish in the current ecosystems.
Scientists emphasize that with a sharp warming on the planet, the ozone layer naturally degrades, which implies the “inevitable conclusion” about the need to realize that such cases can happen again.
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