The years after the asteroid impact were a dark time. The wave of extinctions that followed were caused by soot from raging wildfires that filled the sky and blocked the sun.
The asteroid struck 66 million years ago and killed many forms of life. Mass extinctions that played out over time were caused by environmental changes that were caused by the impact. The dense clouds of ash and particles that spread over the planet may have triggered an extinction that would have left parts of Earth in darkness for up to two years.
During that time, photosynthesis would have failed. According to research presented at the annual meeting of the AGU, the decline could have continued for decades more even after sunlight returned.
Wipeout is History's most mysterious extinctions.
An asteroid traveling at approximately 27,000 mph slammed into Earth during the last part of the Cretaceous period. It was about 12 kilometers in diameter and left behind a scar known as the Chicxulub crater, which spans at least 150 km in diameter and is located in the Gulf of Mexico near the Yucatn Peninsula. The extinction of 75% of life on Earth, including all non-avian dinosaurs, was caused by the impact.
The post-asteroid "nuclear winter scenario" was proposed by scientists in the 1980s, and it suggested that darkness played a part in the crash.
In the past decade or so, researchers have developed models showing how darkness may have impacted life, according to an email from Roopnarine.
The common thinking is that global wildfires would have been the main source of fine soot that would have been suspended into the upper atmosphere. The amount of incoming sunlight would have been reduced if the concentration of soot was high.
An artist's concept shows a broken asteroid. The extinction of the dinosaurs is thought to have been caused by a giant asteroid that broke up in the main asteroid belt between Mars and Jupiter. The image is from NASA/JPL-Caltech.
There were dark days.
Scientists reconstructed ecological communities that existed at the time of the asteroid impact to model the effects of long-term darkness. The Hell Creek Formation is a fossil-rich expanse of sandstone and shale that spans over parts of Montana, North Dakota, South Dakota and Wyoming.
The paleo community was reconstructed reliably because the fossil record is well-sampled and well-understood.
They created simulations that showed the rate of extinction in the fossil record, and exposed their communities to periods of darkness lasting between 100 and 700 days. The email said that the darkness would have reached its maximum in a few weeks.
After a period of darkness that lasted up to 150 days, the researchers found that the environment could recover. Some species went extinct and patterns of dominance shifted after 200 days, according to the scientists. extinctions spiked dramatically in the simulations where darkness lasted for the maximum duration. The models suggest that the Hell Creek communities experienced about two years of darkness.
The darkness could have persisted in the Hell Creek area for up to two years because of atmospheric flow and temperature variations.
The researchers found that once the tipping point was reached, the system could eventually rebound with a new distribution of species, but it would take decades. It took 40 years for the Hell Creek communities to start to recover after they went dark for 700 days.
Live Science published the original article.
