The day the dinosaurs died
A young scientist has found a record of the most significant event in the history of life on Earth. Stunning fossils show what happened when a huge asteroid slammed into the Gulf of Mexico.
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 asteroid 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 Hiroshima bombs. Around 25 trillion metric tons of debris were flung into the atmosphere, spreading across the western hemisphere and into outer space. Giant tsunamis ravaged the coasts. Powerful earthquakes were triggered.
In that moment, the Cretaceous period ended and the Paleocene (which we are still living through) 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 PhD student named Robert DePalma claims to have found fossils from the day of impact at a site in North Dakota, US.
A scientific study describing the fossil site was published in the journal PNAS yesterday. 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, palaeontologist Jan Smit told the magazine.
The site is covered in millions of tektites (tiny 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 change, 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 change was killing the 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.
- Which is the bigger threat: asteroids or climate change?
- What do you think killed the dinosaurs?
- Imagine you have an interview with Robert DePalma. What three questions would you ask him about his discovery?
- You have £1 billion to spend on protecting the human race from extinction. How would you spend it? Write a short report explaining your suggestion.
Some People Say...
“The dinosaurs became extinct because they didn’t have a space programme.”Larry Niven
What do you think?
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 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 yesterday, it did not contain information about the dinosaurs which appears in The New Yorker article. DePalma says he will publish more about those later.
- Hiroshima bombs
- Hiroshima is a city in Japan. In August 1945, the US dropped an atomic bomb on the city which killed 80,000 people and wounded tens of thousands more. Another bomb was dropped on the city of Nagasaki three days later. The bombings effectively ended the Second World War.
- Cretaceous period
- A 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.
- Named after a small town near the epicentre of the 100-mile crater it left behind.
- These tiny stones are formed by the molten rock of an asteroid impact. The ones found at the site matched the chemistry of the Chicxulub crater.
- Volcanic eruptions
- There was a lot of volcanic activity at the end of the Cretaceous period, and it was undoubtedly changing the planet’s climate by spewing gas and dust into the air.