Global cooling by volcanism ushered in the age of the dinosaur: study

Researchers argue that low temperatures stemming from volcanic activity led to the fourth mass extinction, allowing dinosaurs to thrive during the Jurassic period.

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Dinosaurs flourished in the Jurassic after a volcanic eruption 201 million years ago wiped out many marine and land animals, leaving them capable of evolving and growing.

Now, more details about this eruption and the mass extinction have been revealed . Researchers demonstrated how low-temperature magma slowly heated sedimentary rocks, leading to high sulfur dioxide content and low carbon dioxide emissions, a process that cooled the Earth.

Researchers in Japan, Sweden and the US have unearthed evidence that low temperatures stemming from volcanic activity led to the fourth mass extinction, allowing dinosaurs to thrive during the Jurassic period.

Large volcanic eruptions create climatic fluctuations, giving way to evolutionary changes. However, it is the volcanic temperature of the eruption that determines whether the climate cools or warms.

Since the appearance of the first animals, there have been five mass extinctions. The fourth mass extinction occurred at the end of the Triassic period, approximately 201 million years ago. This mass extinction caused the extinction of many marine and terrestrial animals, especially the large-bodied crocodilian line reptiles known as pseudosuchia. Approximately 60-70% of animal species disappeared. As a result, small-bodied dinosaurs were able to grow and thrive.

Mass eruptions and extinctions

Scientists believe that the fourth mass extinction was triggered by eruptions in the Central Atlantic Magmatic Province, one of the largest regions of volcanic rock. But the correlation between the eruption and the mass extinction has not yet been clarified.

Using sedimentary organic molecule analysis and a heating experiment, current Tohoku University Professor Emeritus Kunio Kaiho and his team demonstrated how low-temperature magma slowly heated sedimentary rocks, causing high sulfur dioxide ( SO2) and low carbon dioxide (CO2) emissions.

SO2 gas was distributed throughout the stratosphere, turning into sulfuric acid aerosols. The instantaneous rise in global albedo caused short-term cooling, which could have contributed to the mass extinction.

Kaiho and his team took samples of marine sedimentary rocks from Austria and the UK and analyzed the organic molecules and mercury (Hg) in them. They found four discrete enrichments of benzo[e]pyrene + benzo[ghi]perylene + coronene-Hg.

The discovery of low coronene in the first enrichment was particularly revealing. The second, third and fifth mass extinctions had high concentrations of coronene. A low concentration indicates that low-temperature heating caused a high release of SO2 and global cooling.

“We believe the extinction was caused by large volcanic eruptions because the benzo[e]pyrene + benzo[ghi]perylene + coronene anomaly could only be seen in the time frame of the mass extinctions,” Kaiho said in a statement.

Kaiho’s team is now studying other mass extinctions in hopes of better understanding the cause and processes behind them.

(With information from Europe Press)