By Jonny Lupsha, Wondrium Staff Writer
Dinosaurs were still on the rise when the fatal asteroid struck, CNN reported. While many scientists believe dinosaurs were on their way out, new research suggests they would have continued to rule the Earth. Drastic atmospheric change has nearly ended life on Earth many times.
According to CNN, dinosaurs were not, in fact, on the wane when a city-sized asteroid struck Earth, wiping most of them out. “University of Bath researchers say that, after looking at a greater number of dinosaur groups, their more up-to-date and detailed family trees show that dinosaurs on every continent were in fact flourishing,” the article said. Earlier research had suggested that dinosaurs were already beginning to die out when they went extinct.
When the asteroid in question struck Earth, the impact itself didn’t kill the dinosaurs directly. However, it caused such drastic atmospheric changes to the planet that it made life for non-avian dinosaurs impossible.
It wasn’t the first time a sudden, violent atmospheric change nearly wiped out all life on Earth.
The Great Oxygenation Event
According to Dr. Stuart Sutherland, Professor in the Department of Earth, Ocean and Atmospheric Sciences at The University of British Columbia, before there was oxygen in the atmosphere, the atmosphere was dominated by methane, causing such effects as bacteria thriving in harsh conditions and a sky with a pink hue.
At this time, iron was mostly found in the ocean in a reduced ferrous state. When oxygen came into Earth’s system, iron oxides were created, though eventually more oxygen was produced than could be used up by iron, causing that oxygen to travel up into the atmosphere.
This was called the Great Oxygenation Event.
“Oxygen was highly toxic to the early biosphere, and life had evolved and developed in an oxygen-free Earth, which explains probably why many of Earth’s most primitive organisms today are found in environments that we consider extreme and have very little oxygen in them,” Dr. Sutherland said. “They have effectively retreated from this new toxic gas; this great oxygenation event has been renamed by some as the Great Oxygenation Crisis.
“Perhaps it witnessed the first mass extinction at the microbial level that the Earth is ever going to see.”
Toxic Oxygen?
The current oxygen-rich atmosphere is certainly beneficial to life on Earth, but it came at a great cost. Dr. Sutherland pointed out that this transition to an oxygenated atmosphere had big consequences for our greenhouse blanket on a literally worldwide scale.
“If you pile a lot of oxygen into an atmosphere that is really very concentrated in methane, you are going to go through a simple chemical reaction,” he said. “You are going to oxidize that methane and produce carbon dioxide and water.”
This doesn’t seem like a problem, since carbon dioxide is a greenhouse gas anyway. However, it’s not that simple.
“Remember, carbon dioxide is a lot less effective a greenhouse gas than methane is,” Dr. Sutherland said. “What we would have seen is the skies turning from pink to blue, and as they did, global temperatures would start to plummet.”
This suggests that at one point, the Earth suffered a mega-glacial period in which virtually the entire planet was covered in ice—a snowball Earth that stretched from pole to pole. Such a drastic change, from a methane-based atmosphere to an oxygenated one, and finally to an ice world, far preceded the atmospheric change that wiped out the dinosaurs.
Edited by Angela Shoemaker, Wondrium Daily
Dr. Stuart Sutherland contributed to this article. Dr. Sutherland is a Professor in the Department of Earth, Ocean and Atmospheric Sciences at The University of British Columbia (UBC). Raised in the United Kingdom, he earned an undergraduate degree in geology from the University of Plymouth and a PhD in Geological Sciences from the University of Leicester for his studies on Silurian microfossils called chitinozoa.