You’ve probably read about how a massive asteroid strike ended the era of the dinosaurs and caused their ultimate mass extinction. The geological evidence indicates that, 66 million years ago, the asteroid hit on the Yucatan peninsula of modern Mexico and produced massive earthquakes, volcanic eruptions, tidal waves, and forest fires. The strike threw up a dense plume of dust and debris that turned the world dark and wiped out 99 percent of life on Earth. Thanks to that asteroid strike, the Cretaceous period ended with a bang and the way was clear for mammals — and human beings — to take the dinosaurs’ place at the top of the food chain.
What was it like on the day, 66 million years ago, when the asteroid struck the Earth with such terrible force? Robert DePalma, a doctoral student at the University of Kansas, has found compelling evidence of what happened on that momentous day, and this week he published his findings in the journal Proceedings of the National Academy of Sciences. In 2012, looking at a site called Tanis, in the Hell Creek geological formation in North Dakota, DePalma found layers of perfectly preserved animals and fish fossils at the precise boundary between the Cretaceous period and the Tertiary period that followed it — the very day when the asteroid struck the Yucatan.
The geological evidence shows that the asteroid strike created a magnitude 10 or 11 earthquake that generated seismic waves that reached out thousands of miles. In prehistoric North Dakota, which like much of the North American continent was covered by an inland sea, the seismic waves produced a water surge that threw fish onto shores to suffocate — producing the layers of fish and animals that DePalma found. At the same time, molten material was hurled into the atmosphere. In the geological formation, DePalma found bone, teeth, and hatchling remains of many dinosaur groups, including an intact dinosaur egg complete with embryo — indicating that the dinosaurs survived that fateful day, although their ultimate day of reckoning was coming.
In an article in the New Yorker, DePalma describes his find as “like finding the Holy Grail clutched in the bony fingers of Jimmy Hoffa, sitting on top of the Lost Ark.” Thanks to him, we now know a lot more about the day that the ground buckled and snapped, the waters surged, the skies were lit with fire, and the world changed forever.