A study finds the causes of the most important extinctions on Earth! So what is it?

Oxygen depletion and rising levels of hydrogen sulfide in the oceans may have been responsible for one of Earth’s most significant mass extinctions more than 350 million years ago, a new study finds. The changes were likely driven by rising sea levels and have some eerie similarities to conditions we see today.

The researchers studied samples of black shale from the Bakken Formation. It is a 200,000-square-mile (518,000 sq km) area partially laid during the late Devonian period that includes parts of North Dakota and Canada and is one of the largest contiguous deposits of natural gas and oil in the United States. The team found evidence that Earth experienced periods of oxygen depletion and hydrogen sulfide expansion, which likely contributed to the mass extinction events that devastated Earth during the Devonian period (419.2 and 358.9 million years ago), or the “age of fish.”

Hydrogen sulfide is formed when algae decompose on the ocean floor. This decomposition process also depletes the oxygen.

“There have been other mass extinctions likely caused by hydrogen sulfide expansion before, but no one has ever comprehensively studied the effects of this killing mechanism during this critical period of time,” University of Maryland geologist study co-author Dr. Alan Jay Kaufman said in a statement. The history of the Earth,” according to the specialized scientific site “Live Science”.

During the Devonian period, features of marine life were identified. The jawless fish known as placoderms diversified widely throughout the oceans that surrounded the supercontinents Gondwana and Euramerica. The oceans were also filled with early trilobites and ammonites, and extensive coral reefs surrounded the continents. On land, the earth saw its first forests of ferns and early trees. By the middle of the Devonian period, the first tetrapods, Tiktaalik roseae, crawled from the surface of the sea.

However, the Devonian period also saw some of the most important extinctions in Earth’s history, including one of the five infamous “mass extinction” events that led to the evolution of the plants and animals we know today. The early ectoderms, trilobites, and ammonia disappeared, while sharks and cartilaginous fish-like rays proliferated.

To reveal more about the Devonian extinctions, the research team analyzed more than 100 core samples excavated from black shale deposits in the Bakken Formation. These organic-rich sediments accumulated near the end of the Devonian period, recording the environment in its chemical composition.

In this context, the team found evidence of “hypoxic events”; The water was completely depleted of oxygen, according to the researchers of the study, which was published on March 8 in the prestigious scientific journal Nature.

“These sharp declines are likely related to a series of rapid rises in sea level caused by the melting of the Antarctic ice sheets during the earlier Silurian period (443.8 million to 419 million years ago),” Kaufman commented. At the same time, plants transformed the rocky ground into soil, which would release nutrients to flow into the high oceans. The influx of nutrients into the oceans would have led to megaalgal blooms that died, decomposing and absorbing oxygen. As they decomposed, the dead algae released hydrogen sulfide, which increased levels of the toxic chemical. Oxygen-depleted seas were too much for marine life in the Devonian period. Therefore, researchers estimate that 75% of life became extinct at the end of the Devonian period.

“The Devonian mass extinction is a warning for us today,” the study authors concluded in their statement. Oxygen-depleted dead zones appear in the oceans every year in places like the Gulf of Mexico and the Baltic Sea. Extensive use of fertilizers and sewage runoff boost nutrient levels in the ocean and encourage megaalgal blooms. And as the Earth gets warmer and sea levels rise, the oceans won’t distribute oxygen either.” “Past mass extinctions can help scientists understand the consequences of our actions today,” they added. Although the causes of sea level rise and nutrient flow in the Devonian period are different from those of today, they may have led to the same outcome. Massive loss of life and our planet’s oceans.