Approximately 185 to 85 million years ago, Earth's oceans and continents underwent a series of dramatic changes that caused mass extinctions of marine life and deeply impacted the subsequent course of evolution. Researchers have identified oceanic anoxic events as a key factor in these ecological catastrophes. Anoxic events occur when oxygen levels in the oceans drop dramatically, creating 'dead zones' where most marine life cannot survive. These periods, lasting from one to two million years, were associated with tectonic activities and intense volcanic activity.

The period known as the Mesozoic, when dinosaurs roamed the Earth, was marked by the breakup of the supercontinent Gondwana. This process not only transformed the appearance of the planet but also had dramatic effects on oceanic ecosystems. Geologists discovered that the movement of tectonic plates and volcanic eruptions caused the release of massive amounts of phosphorus into the oceans. Phosphorus, a crucial nutrient for life, stimulated the accelerated growth of marine organisms, but at the same time led to the excessive accumulation of organic matter that depleted oxygen from the water masses.

These anoxic events disrupted the ecological balance and triggered mass extinctions of marine species. These catastrophes had long-term consequences, as the deposits of organic material from these periods are today a major source of commercial oil and gas reserves. Researchers warn that excessive fertilization of today's agricultural lands has a similar effect on modern oceans, causing the spread of dead zones and reduced oxygen levels in the water.

Oceanic anoxic events represent a key indicator of how tectonic changes can cause disasters that shape the evolutionary path of life on Earth. Today, the effects of similar processes, although on a much smaller scale, can be observed in the ways human activities impact the environment. Scientists believe that studying these ancient geological events can help predict future climate and environmental changes, which is important for developing strategies to conserve our planet.

Extensive research into geological cycles, such as the breakup of the supercontinent Gondwana, clearly shows how deep processes within Earth's crust can have far-reaching consequences for life on its surface. According to experts, periods of intense volcanic activity and changes in ocean chemistry reflect the complexity of the interactions between the internal and external layers of our planet, which proved to be particularly important during the Mesozoic.

Given the increasing climate and ecological challenges we face today, such historical research offers valuable lessons on how Earth might respond to future stresses. Understanding the history of life's evolution through the lens of geological events provides key insights that could aid in shaping more sustainable approaches to managing natural resources and protecting the environment.

Source: University of Southampton