Scientists have found evidence of what exactly may have destroyed the dinosaurs 66 million years ago.
The cause of the mass extinction of the dinosaurs, which occurred in the Late Cretaceous and early Paleolithic, remains one of the greatest scientific mysteries. There are a number of hypotheses trying to explain it, but none of them have had the necessary substantiation so far.
Recently, however, in North Dakota, scientists found a unique “death field” full of animal and fish fossils, dating from the same period, which may provide an answer not only to the question of what caused the extinction but also how it happened.
A Mind-Boggling Discovery
The petrified fish are stacked on top of each other. This suggests that they were washed ashore together, where they remained. This asteroid impact was deadly for most species on Earth, including dinosaurs. Credit: University of California, Berkeley
In 2013, paleontologist Robert DePalma discovered a fossil cemetery at an excavation site in the Hell Creek Formation. There he found fossilized remains of fish stacked on top of each other, as well as burnt tree trunks, dead mammals, insects, bones of mosasaurs, marine microorganisms, marine cephalopods, and partial remains of Triceratops.
Even then, he suspected that this accumulation of dead creatures in one area could be the result of an asteroid impact that killed the dinosaurs.
What was the last day for dinosaurs like?
It is known that about 66 million years ago, a meteorite with a diameter of about 10-15 kilometers fell on the Yucatan Peninsula. According to the main hypothesis, the dust from the explosion reduced the transparency of the atmosphere for many years, which caused a global cooling on the planet, which led to the extinction of not only dinosaurs but also 75% of all animal species.
The discovery of fossils in the Hell Creek Formation has helped scientists reconstruct events that took place immediately after the fall.
Small tektites, commonly known as glass rain, with a size of about 1 millimeter were also discovered in situ. Credit: Robert DePalma
In both layers of the found fossils, there is an excess amount of iridium, and only in the lowest layer, there are tektites. Consequently, the fossils were formed as a result of two different events.
First, due to the impact, giant waves rose in the waters of the inland sea in the territory of modern North Dakota. Then, a “glass rain” of tektites (balls of hot rock with a diameter of about 5 millimeters) began to fall from the sky, which set fire to most of the vegetation on land.
The rising sea turned into a 10-meter wall of water. When it reached the mouth of the river flowing into it, countless freshwater fish washed up on the shore, where it was bombarded by glass rain for almost half an hour.
The second event also included another massive wave, which flooded the coast and buried fish, dinosaurs, and all other species under tektites and sand. Small spheres from the “glass rain” were found in the gills of more than half of all fish. And the fossil deposits are covered with clay with a high concentration of iridium – a metal that is almost never found on Earth but is abundant in asteroids.
“When we proposed the impact hypothesis to explain the great extinction, it was based just on finding an anomalous concentration of iridium — the fingerprint of an asteroid or comet,” said Alvarez. “Since then, the evidence has gradually built up. But it never crossed my mind that we would find a deathbed like this.”
It is interesting to mention some approximate estimates calculated by Walter Alvarez, a UC Berkeley professor. He addressed the speed of the falling tektites and suggested that they might have rained down on Earth with the mind-blowing 100-200 miles per hour.
How would you feel if something like that hit you a thousand times in seconds? According to Alvarez, at this velocity, the glass rain would have killed you as it probably did with countless animals and dinosaurs.
I share the same opinion as to the people behind the discovery of this “death field” – this could be the beginning of a new era for historical discoveries about dinosaurs. No other fossil site in the world has such an abundance of remains from around the period when not only dinosaurs but most of the species in the world came to their end.
Sources: ScienceAlert, Forbes.