The day the dinosaurs died

It was a day about 66 million years ago. Dinosaurs still roamed the Earth. But then, suddenly, they didn't — because a six-mile-wide asteroidA small body in space, made of metal and rock material. Asteroids usually orbit the sun, but if knocked off course they can be drawn into Earth’s gravity and fall towards it. travelling at 45,000mph blasted into the Earth's surface near modern-day Mexico. It was, possibly, the most significant day in Earth's history. The impact released more energy than a billion HiroshimaA Japanese city destroyed by an atomic bomb in World War II. bombs. Around 25 trillion metric tons of debris were flung into the atmosphere, spreading across the western hemisphere and into outer space. Giant tsunamisTidal waves. The term comes from two Japanese words meaning harbour and waves. ravaged the coasts. Powerful earthquakes were triggered. In that moment, then Cretaceous periodA 79-million-year period which followed the Jurassic period. During this period, the continents formed and were divided by oceans. This cooled the planet’s temperature. Famous dinosaur species, such as the Triceratops and Tyrannosaurus rex, lived in this time. Mammals already existed, but they did not flourish until the dinosaurs died out. ended and the PaleoceneA geological epoch, or time period, that existed between 66 million and 56 million years ago.  began. With dinosaurs gone, mammals began to evolve and take over. Scientists have suspected that the dinosaurs were killed by an asteroid known as Chicxulub for around 20 years. Now, a PhDAn abbreviation for a Doctorate of Philosophy. Students study for several years and usually do their own extensive research to gain a PhD. student named Robert DePalma claims to have found fossils from the day of impact, at a site in North Dakota, USA. A scientific study describing the fossil site was published in the journal PNAS. It was accompanied by a long article in The New Yorker, in which a journalist visits the site and interviews DePalma. "This is the first time we see direct victims" of the asteroid impact, palaeontologistA scientist who studies fossils to learn about history. Jan Smit told the magazine. The site is covered in millions of tektitesTiny balls of glass formed by the molten rock of an asteroid impact.. They have been dated as 65.76 million years old, around the time Chicxulub is thought to have hit. Some of the tektites were found in the gills of dead fish. It was as if they had been inhaled as the fish struggled for life in the water. DePalma also claims to have found an egg containing a dinosaur embryo at the site. If true, this might help to disprove the theory that the dinosaurs were already dying out when the asteroid hit. However, some scientists are still sceptical. The scientific study was about the geology of the site, not the dinosaurs found there. For that reason, "I am left with more questions than answers," palaeontologist Steve Brusatte told The New York Times. There is still fierce debate among scientists about what killed the dinosaurs. The asteroid? Or were they already doomed by climate crisis brought on by volcanic eruptions? It is not just a scientific question. If it was the asteroid, it left a dire warning for humanity: the end could be sudden and unpredictable. But if the asteroid was a coincidence and climate crisis was killing dinosaurs anyway, we are left with a different message. They could not have known their fate, but humans have the gift of foresight and scientific knowledge. We have time to help ourselves before it is too late. Q & A What do we know? There is a lot of evidence that DePalma's site in North Dakota is filled with remains from the day — if not the hour — that the Chicxulub asteroid hit Earth. This comes from the tektites found there, which are the right age and which match the geochemistry of the crater that the asteroid left behind in Mexico. There is also evidence that the site was swamped with water, bringing fish and other sea creatures with it. What do we not know? How seriously to take all of DePalma's claims. Fellow palaeontologists have accused him of being prone to exaggeration. And while the geology of the site was published in a scientific study, it did not contain information about the dinosaurs which appears in The New Yorker article. DePalma says he will publish more about those later.KeywordsAsteroid - A small body in space, made of metal and rock material. Asteroids usually orbit the sun, but if knocked off course they can be drawn into Earth’s gravity and fall towards it.