Chinese researchers have unveiled a significant link between oceanic oxygenation and the rapid evolution of early animals during the Cambrian Explosion, shedding new light on one of the most profound events in the history of life on Earth.
The Cambrian Explosion, which occurred approximately 541 million years ago, marked a period of unprecedented increase in the diversity, complexity, and disparity of early animal life. Scientists have long debated the driving forces behind this evolutionary milestone, with global oceanic oxygenation often proposed as a key factor. However, the exact relationship between rising oxygen levels and early animal evolution has remained elusive.
A team of researchers from the University of Science and Technology of China has conducted a groundbreaking study analyzing excess barium contents and isotope compositions in Cambrian metalliferous black shales from the Yangtze Block in South China. Their findings indicate that global oceanic oxygenation across the Ediacaran-Cambrian transition may have significantly altered the marine chemical environment in ways that promoted the diversification of early animals.
“We discovered that the increase in oceanic oxygen levels led to the oxidation of sulfide, expanding the sulfate reservoir in the oceans,” the researchers explained. “At the same time, this process decreased the barium reservoir through the precipitation of barite.”
High concentrations of barium are known to inhibit the survival rate of aquatic organisms. By reducing the levels of both sulfate and barium—elements that can be detrimental to animal life—the changing ocean chemistry may have improved the habitability of marine environments, paving the way for the Cambrian Explosion.
This study challenges previous notions that oceanic oxygenation was merely a consequence of the Cambrian Explosion rather than a cause. It suggests that positive feedback loops between oxygen levels and animal evolution played a crucial role in this transformative period.
The research enhances our understanding of the complex interplay between Earth’s geochemical cycles and biological evolution. It underscores the importance of environmental factors in shaping the trajectory of life on our planet.
The study was published in the journal National Science Review.
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Chinese researchers unveil key factors of Cambrian Explosion of life
cgtn.com
