In the 4.6 billion-year evolutionary history of Earth, a species dominated the planet for an astonishing 160 million years. At that time, no other creature could challenge its position of supremacy—this was the era of the dinosaurs. However, even the mighty dinosaur empire could not escape destruction when disaster struck unexpectedly. What exactly happened on the last day of the dinosaurs? Why is it widely believed that their extinction was caused by an asteroid impact? Scientists have unveiled the dramatic events of that day, 66 million years ago, at the renowned Tanis dinosaur site.
According to the excavation site, a dinosaur fossil was discovered with all its joints intact, its surface still covered in skin, and no signs of bites or tears. CT scans revealed that it had been torn apart by some immense force capable of instantly severing bodies, likely from a massive flood or a powerful impact. This hypothesis was further supported by another new discovery: in 2019, scientists found an almost complete fossil of a Cretaceous turtle during the excavation of dinosaur fossils. The turtle had a piece of wood inside its body, piercing from its head to its tail, similar to the previously discovered dinosaur, which also died from a strong impact against a tree branch. However, these two new findings were not enough to prove the connection between the extinction of dinosaurs and the asteroid impact event.
The truth began to emerge with the discovery of a Cretaceous fish fossil. Many spherical particles were found inside the fish's skull. Analysis revealed that the elemental proportions of these particles did not match any substances on Earth, suggesting they could be fragments of an asteroid. After the asteroid struck Earth, the ejected debris entered space. Some, traveling at extreme velocities, even escaped Earth's gravity and landed on the moon, while most of the fragments were pulled back to Earth by gravity. Some fell into the water and were the gills of fish, causing their immediate death. Therefore, the death of these fish and many other related clues led to the inference that the extinction of dinosaurs was highly likely due to an asteroid impact. But what exactly happened that day?
On a day 66 million years ago, a 10-kilometer diameter asteroid known as the Chicxulub asteroid hurtled towards Earth at a speed of 70,000 kilometers per hour, striking the ocean where the Yucatan Peninsula in Mexico is now. The impact's explosive power was equivalent to a billion times that of an atomic bomb. The violent collision turned all life within a 1,500 km radius into ashes. Over three trillion tons of debris were ejected into space, and the shockwave traveled at thousands of kilometers per hour, triggering a massive tsunami.
At that moment, Tanis, 3,000 km away from the impact site, had not yet realized the impending doom. The dinosaurs there were still living peacefully. The disaster quickly advanced towards Tanis, obliterating everything in its path. When the seismic waves reached Tanis, the violent shaking caused the river water to churn violently, and a 10-meter high wall of water along the waterways, drowning many animals. Although the larger dinosaurs escaped this catastrophe, the disaster was far from over.
Next, the ejected materials from the explosion rained down, with high-temperature particles igniting widespread wildfires. Dinosaurs on land and in the sky had nowhere to hide. The dust that filled the sky blocked sunlight for decades, plunging the Earth into an extreme cold, causing plants to wither due to their inability to photosynthesize. The dinosaurs that survived could not adapt to the environmental changes and perished, leading to the collapse of the entire ecosystem. Earth fell silent. Thus, the most captivating era in the history of life, the age of dinosaurs, ended in the catastrophic Cretaceous extinction.