Ancient rocks in southern China have unveiled the truth about a horrific and mysterious event that killed nearly half of Earth’s life forms.
The Cambrian geological record from the Yangtze Platform, a vast highland in southern China that was once the floor of an ancient ocean, has revealed a particular chemical element called molybdenum.
Molybdenum indicates a form of apocalyptic disaster that is hard for humans to imagine: “Toxic gas tsunamis.”
Fossils of some extraordinary Cambrian creatures that studies from China show were wiped out by “toxic gas tsunamis” – (Photo: SHUTTERSTOCK/LIVE SCIENCE).
According to Live Science, around 530 million years ago, when most life still belonged to the oceans, Earth experienced the Cambrian explosion.
This event led to the emergence of a variety of extraordinary life forms, with a significant leap in evolution compared to the previous era. Although they had entirely strange forms, these creatures were indeed the ancestors that laid the foundation for today’s rich biodiversity on Earth.
However, just 20 million years after that event, at the mark of 510 million years ago, a massive extinction suddenly occurred.
For a long time, scientists have been trying to explain the cause of this catastrophic “apocalypse” event that killed 45% of the newly emerged species across the oceans. Many hypotheses have been proposed, including cosmic impacts such as supernovae.
However, molybdenum in ancient Chinese rocks indicates something even stranger. Molybdenum can combine with sulfur to form insoluble compounds, which then accumulate in sediments.
Therefore, its abundant presence signifies that the levels of hydrogen sulfide were once very high in the water.
Hydrogen sulfide is toxic to both ancient organisms and modern life forms. This compound rose in conjunction with a phase of severely reduced oxygen levels, creating a “toxic tsunami” sweeping across the oceans.
According to Dr. Chao Chang, a geochemist from Northwestern University (Xi’an, China), hydrogen sulfide can be lethal to all marine animal species.
Earth was even quite fortunate that only 45% of life forms became extinct in an event that could have turned into an “apocalyptic day” for the planet.
The cause of this toxic gas wave remains unclear. However, in a paper published in Geophysical Research Letters, the authors suspect that the excessively strong biological explosion contributed to the disaster.
The ocean “population” surged exponentially, leading to a series of organic materials from their bodies sinking to the ocean floor. The decomposition became a feast for trillions of bacteria. They chewed through sulfates, converting them into the byproduct hydrogen sulfide, filling the water with it.
Even though life exploded during that period, this primordial ecosystem was still incomplete, lacking the mutual supplementation in the life cycle that allows Earth’s organisms to self-balance ecologically today.
Thus, disaster struck, like a trial run. While it exterminated many creatures, it also set the stage for the emergence of a new generation of life forms that were more evolved, better adapted, and capable of higher levels of mutual balance.
