According to a new study, the asteroid that killed the dinosaurs impacted Earth sometime between the spring and early summer months. If it would have hit 6 months earlier or later, the results may have been much different.
Detailed analysis of mostly fish fossils that were found at a site in North Dakota called Tanis revealed that they died as a result of when the asteroid struck Mexico’s Yucatán Peninsula 66 million years ago and that it happened when the Northern Hemisphere was in the spring or early summer months.
Since this new study has suggested that the impact occurred during the warmer months, it may have had an even larger effect on the loss of life that wiped out around 75% of the species. It is important to note that there are some debates on whether the extinctions were caused by powerful volcanic eruptions that occurred around that same time; or perhaps it was a combination of the volcanoes and the asteroid impact.
The fossils found in Tanis are very important as they could be the first ever direct studies linked to the asteroid impact’s effect on life during that time. But first, the researchers had to calculate which time of the year the fish had died – the majority of the fish were paddlefish and sturgeons. Fish bones have a dark layer (similar to tree rings) during the spring and summer months, followed by lighter colored bands during the fall and winter. Additionally, the two rings contain different ratios of carbon chemical flavors.
When the experts analyzed the bones, they found that the last layer that appeared was the dark colored one which indicated that they died during the spring or summer months. Furthermore, they found that the fish remains consisted of both adults and juveniles which supports even further the timeline theory.
Another hint is that sturgeons migrate to saltwater in the winter and freshwater during the spring and summer – Tanis is a freshwater location. And if those clues aren’t enough, insects found in fossilized leaves as well as the remains of ancient adult mayflies revealed that they died during that same time period.
As for the loss of life, since the impact appeared to have happened sometime during the spring or summer months, it may have caused a lot more extinctions than if it had occurred in the winter time. The authors noted that the warmer months caused many creatures to have “vulnerabilities inherent to this time span, which was a period of growth and reproduction for many animals and plants”.
Whether some of the dinosaurs and other species would have survived if the asteroid would have hit in cooler months remains unclear, but it is interesting to think about. What would Earth be like today if humans and dinosaurs had to live side by side?
The study was published in the journal Scientific Reports.