Question: how did all the dinosaurs die out

Craig McKenzie answered on 23 Jun 2011:

Hi joshum1243,
this is a really good question and one that scientists have been thinking about for a long time. Dinosaurs were around on earth for a very long time up until 64-66 million years ago but relatively quickly disappeared – in less than 2 million years (we know this because we can study the age of the dinosaur fossils we find in the ground). A lot of theories have been put forward to explain why they disappeared so quickly – there is lots of evidence that the dinosaurs didn’t die out all at once but in a series of extinctions. The one we tend to focus on is the last main extinction event (normally called the K-T mass extinction) when most of the last remaining dinosaurs disappeared. It wasn’t just the dinosaurs who seemed to die off in this period either – lots of marine reptiles and pterosaurs (bird like dinosaurs) also died out to. There are still a lot of arguments whether the extinctions were catastrophic (happened very quickly over a few days) or gradual (over hundreds of thousands of years or a even a few million years) but a lot of scientists now agree on the most likely cause of the die off (but we can never really be 100% sure – this is just the most likely cause using the evidence we have right now – it could change if new information is discovered – lot’s of science is like this).

Recently a large group of different types of scientists (palaeontologists, geochemists, climate modellers, geophysicists and sedimentologists) have looked over all the evidence gathered about the possible reasons for the extinction and think it is most likely that dinosaurs died out because of a massive asteroid or comet smashing into a part of the Earth in what is now known today as Mexico and there is still a giant crater there today, although it is very hard to see from the ground because it is so big.

The scientific evidence suggests that the initial impact would have triggered large-scale fires, huge earthquakes, and continental landslides generating tsunamis. After this those dinosaurs who survived were in real trouble when material like dust and particles from the impact would have been thrown into the atmosphere. This amount of dust and gases is likely to have put the planet in darkness for a long time as the sun could not get through and so would have caused a global winter which lasted a long time, and this most probably killed off many of the species that couldn’t adapt. Those that did survive such as the early forms of mammals, amphibians and the insects could then start to dominate the species present on the earth and evolve into the animals we see around us today.

I hope that answer helps you. If you want to do a little more reading about this fantastic subject which has had scientists thinking for a very long time then you could have a look here: http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/