![]() 'What we're left with are basically the seeds of what we have today. But all land animals weighing over 25 kilogrammes died out. After the dinosaurs' extinction, flowering plants dominated Earth, continuing a process that had started in the Cretaceous, and continue to do so today. What survived the asteroid impact?ĭuring the Cretaceous extinction event, plants were less affected than animals because their seeds and pollen can survive harsh periods for longer. The last non-bird dinosaurs were living at a time of environmental change, some of which began millions of years before they went extinct. This also had a strong effect on climate and vegetation.' The continents were drifting around and splitting apart from each other, creating bigger oceans, which changed ocean and atmosphere patterns around the world. Paul says, 'For two million years there was a huge amount of volcanic activity going on, spewing gases into the atmosphere and having a major impact on global climate. The resulting lava outcrop is now known as the Deccan Traps. In what is now central India, there was substantial volcanic activity that, although unrelated to the asteroid impact, was causing problems of its own. This was making things harder for life on our planet. Prior to its crash landing, Earth was experiencing a period of climate change. The blame can't solely rest on the asteroid. The Deccan Traps and global climate change Among them, ammonites, some microscopic plankton, and large marine reptiles all died out.īut the loss made room for the beginnings of the modern world. But it was a massive event affecting all life on Earth, from microorganisms all the way through to dinosaurs,' says Paul. 'There is a lot of discussion over the actual kill mechanism and how long that period lasted. All living things would have been affected in some way, both on land and in the ocean. The reduction in plant life had a huge impact on herbivores' ability to survive, which in turn meant that carnivores would also have suffered from having less food available.īreeding seasons would have been shorter and conditions harsher. Like dominos, this trailed up the food chain, causing the ecosystem to collapse. It didn't completely block out the Sun, but it reduced the amount of light that reached the Earth's surface. 'It sent soot travelling all around the world. A huge blast wave and heatwave went out and it threw vast amounts of material up into the atmosphere. It made a huge crater, so in the immediate area there was total devastation. Paul explains, 'The asteroid hit at high velocity and effectively vaporised. ![]() So how was this global mass extinction caused by a rock hurtling into the coast of Central America? 'Recent redating has refined it, and the date of the dinosaur extinction is 66.0 million years ago.' Why did dinosaurs go extinct?Īround 75% of Earth's animals, including dinosaurs, suddenly died out at the same point in time. There is also evidence of substantial fires from that point in history.įor a long time it was thought that the non-bird dinosaurs died out 65 million years ago.īut Paul explains, 'The dating of those layers of clay around the world is very accurate - it's estimated to within a couple of thousands of years. The dinosaur-killing crash threw huge amounts of debris into the air and caused massive tidal waves to wash over parts of the American continents. It's the second-largest crater on the planet. The asteroid is thought to have been between 10 and 15 kilometres wide, but the velocity of its collision caused the creation of a much larger crater, 150 kilometres in diameter. The impact site, known as the Chicxulub crater, is centred on the Yucatán Peninsula in Mexico. It is exactly the same age as the extinction of the non-bird dinosaurs, which can be tracked in the rock record all around the world.' It's now largely buried on the seafloor off the coast of Mexico. Paul says, 'An asteroid impact is supported by really good evidence because we've identified the crater. How big was the asteroid that killed the dinosaurs? The Alvarez hypothesis was initially controversial, but it is now the most widely accepted theory for the mass extinction at the end of the Mesozoic Era. Any fragment of an asteroid that survives landing on Earth becomes known as a meteorite. They range from a few to hundreds of metres in diameter. Asteroids are large, rocky bodies that orbit the Sun.
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