Scientists are unsure of the exact year when an asteroid wiped off the dinosaurs, but they are confident that the massive space rock hit Earth in the Northern Hemisphere springtime. They also believe that the timing of the disaster may have played a role in determining which animal groups survived the disaster. For the dinosaurs, it made no effect, but it may have made a difference for certain animals, birds, and plants. It could have been the deciding factor.

This was possibly especially true for animals residing in the Southern Hemisphere, where the impact would have occurred in autumn or early winter. “In the Southern Hemisphere, many organisms would have been in hibernation or sheltering. That could have helped them,” says Melanie During from Uppsala University, Sweden. “In spring, you expect animals to be tending to their offspring which are very fragile, or perhaps they are still tending to eggs, waiting for them to hatch or be looking for food. That puts them in a vulnerable position.” Ms. During recently released her findings from a study of fossil paddlefish and sturgeon found near Tanis, North Dakota, which clearly suggest that the fish perished in the spring. Tanis is the site that preserves not only the day a 12km-wide asteroid blasted into the globe 66 million years ago but also the minutes and hours that followed the horrific impact.