Dinosaur Extinction: How the Asteroid Impact Disrupted Vital Life Processes
A groundbreaking study reveals that the devastating asteroid impact 66 million years ago disrupted photosynthesis on Earth, leaving plants unable to survive due to the sun-blocking fine dust, providing new insights into the mysteries of mass extinction
Get the latest updates on incredible scientific breakthroughs and cosmic revelations by subscribing to CNNs Wonder Theory science newsletter. Delve into the wonders of the universe, including mesmerizing discoveries and revolutionary advancements. The era of dinosaurs came to a halt approximately 66 million years in the past, brought upon by a colossal asteroid impact that occurred in a shallow sea near present-day Mexico.
The exact manner in which the cataclysmic impact resulted in the mass extinction of 75% of Earth's species in the subsequent years has remained uncertain. Earlier studies proposed that the release of sulfur and the formation of the enormous Chicxulub crater, spanning 112 miles (180 kilometers), along with the emission of soot from wildfires, led to a global winter and a drastic drop in temperatures.
A study published in the journal Nature Geoscience on Monday suggests that the impact of pulverized rock sending fine dust into the Earth's atmosphere had a significant impact. This dust blocked the sun, preventing plants from carrying out photosynthesis for nearly two years. Lead study author Cem Berk Senel, a planetary scientist at the Royal Observatory of Belgium, stated that the halt in photosynthesis resulted in severe challenges for life and led to a collapse in the food web, triggering a chain reaction of extinctions.
The pink-brown layer in the sediment from a site in North Dakota contained material ejected from the Chicxulub crater that was used as part of the climate modeling study.
Pim Kaskes
An unexpected killing mechanism
Scientists utilized a novel computer model to simulate the global climate following the impact of the asteroid. This model was constructed using existing knowledge of Earth's climate at that time, along with fresh data obtained from sediment samples taken from the Tanis fossil site located in North Dakota. These samples accurately depict a 20-year period after the strike occurred.
The Tanis fossil site serves as a remarkable testament to an event that undoubtedly shaped the course of life on our planet. The discovery of fossilized fish at the site has provided crucial insight, revealing that the asteroid collision transpired during the spring season off the Yucatán Peninsula in Mexico. Additionally, other fossils discovered at this site offer unparalleled details regarding the catastrophic events of that fateful day.
The sample collected from the site and analyzed for the new study revealed the presence of silicate dust particles. These particles were forcefully propelled into the atmosphere as a plume of ejecta before eventually descending back to Earth.
Through their findings, the team concluded that this fine dust could have lingered in the atmosphere for a period of up to 15 years following the impact of the asteroid. As a result, the researchers proposed that the global climate may have experienced a significant cooling effect, potentially reducing temperatures by up to 15 degrees Celsius.
The research was the first comprehensive study done on these dust particles.
"While it was widely believed that extreme cold was the primary cause of death following the Chicxulub impact, it is important to recognize that the halt of photosynthesis after the impact is also a significant mechanism," stated Senel.
Within a matter of weeks or months following the impact, the planet experienced a widespread cessation of photosynthesis. This extended period, spanning nearly two years, witnessed a complete absence of photosynthetic activity," Senel further explained. "Subsequently, the process gradually began to restore itself, signifying the onset of recovery, which takes approximately three to four years to fully progress."
A Helos laser-diffraction grain-size analyzer was used to measure the properties of the dust contained in the sediment samples.
Pim Kaskes
Senel discovered that the suspension of photosynthesis, the process in which plants utilize sunlight, water, and carbon dioxide to generate energy and oxygen, was directly attributed to the expulsion of minuscule dust particles into the atmosphere, which obstructed the sun.
Paleontologist Alfio Alessandro Chiarenza, a postdoctoral research fellow at the University of Vigo in Spain, expressed that the study has played a crucial role in unraveling the mysteries related to the mass extinction event. According to Chiarenza, the paper offers more detailed information about the composition, properties, and duration of the fine dust that was released from the impact site. This fine dust contributed to the global darkness experienced during the impact winter. It is important to note that Chiarenza was not involved in the study.
Chiarenza added that this newfound data allows for a more thorough investigation into the processes and duration, offering insights into the mechanisms responsible for obstructing solar radiation. As a consequence, photosynthesis undergoes a shutdown, leading to a considerable decrease in temperatures below the conditions suitable for non-avian dinosaurs.
