About sixty-five million years ago, our planet lived through a horror scenario that led to the mass extinction of the End of the Cretaceous (of which its exact duration is unknown), the fifth and last in the history of planet Earth so far. .
In it, most of the terrestrial animals, (among them the powerful dinosaurs) and also a large part of the marine fauna, succumbed. The trigger was a rock fragment ten kilometers in diameter that hit the Earth destroying everything in its path.
After years of work and research, scientists at UC Berkeley have now found the first victims of this destructive event. It is a truly unique and fossilized cemetery, as the University describes in a statement, rich in organic matter: burned trees, coniferous branches, dead fish and mammals, mosaur bones, insects, and even the partial carcass of a Triceratops , in addition to other marine microorganisms (such as dinoflagellates and cephalopods).
They all died at the same time.
As the researchers describe: “In no other section of the KT limits (a geological time horizon known as the Cretaceous-Paleogene limit) can such a collection be found, consisting of a large number of species representing different ages of organisms and different stages of life, all of which died at the same time, on the same day.
The evidence even allows to recreate in detail ‘the scene of death’ (minutes after impact), which has been excavated in an unprecedented fossil site in North Dakota. Let’s go there.
Image: Fossilized fish stacked on top of each other, suggesting they were dumped ashore and died stranded on a sand bar after the seiche retreated. / Robert DePalma.
Reconstruction of the facts
At the instant of impact, the asteroid ( larger than Mount Everest ) was almost equal in height to that of passenger planes in the air. It was moving at more than seventy thousand kilometers per hour ( faster than a bullet ) and hit what is now the Gulf of Mexico, next to the Yucatan peninsula.
The asteroid destroys everything it touches in the area of impact ; even the asteroid itself, which disintegrates instantly. It unleashes an energy equivalent to millions of nuclear bombs detonated at the same time.
No place is safe anymore on Earth, due to the unleashed tsunami and the shock wave; However, the area with the most destruction is the zero impact zone, where a tsunami wave was generated in an inland sea that killed and buried fish, mammals, insects … and other larger animals.
A violent earthquake lifted giant waves in the waters of an inland sea in what is now North Dakota. Then small pieces of glass began to fall from the sky like drops of water. The rain of crystals was so strong that it could have set fire to much of the vegetation. In the water, the fish struggled to breathe as small glasses clogged their gills.
One of the consequences of the shock wave is the formation of a large wall of water, which advanced, throwing hundreds (even thousands) of freshwater fish, which were buried in the mud several centimeters deep. Afterward, a torrent of rocks, fine sand, and more glass rain continued for another 10 to 20 minutes, before a second large wave flooded the shoreline, covering the organic debris with gravel, sand, and fine sediment, sealing it off for sixty and five million years, to the present day.
Glass beads or tektites, formed from rocks melted on impact.
However, the investigation is long. Researcher Mark Richards and UC Berkeley Graduate School professor Walter Alvarez were the first to hypothesize forty years ago that an asteroid impact caused the mass extinction.
Both scientists were summoned by the study authors, paleontologist Robert DePalma and Dutch scientist Jan Smit, to consult on the rain of ‘glass beads’ and tsunami waves that buried and preserved the fish. Interesting is the formation of the pearls in question, called tektites , which were formed in the atmosphere from rocks melted by the impact.
This ‘killing field’ was established, according to the researchers, a few minutes after the asteroid impact, which triggered, not only the local consequences of the collision, but a global catastrophe that would wipe out 75 percent of the life on Earth, (including all terrestrial dinosaurs).
