Today’s Ask a Scientist post is brought to you by Lizzie Lieschke! Lizzie is a PhD student working on cancer research, but she also has a keen interest in all things prehistoric. Today, she is answering all your most burning questions about dinosaurs.
How many dinosaurs were there in the past? – Gabriel, 8
So far scientists have discovered and named about 900 dinosaur species from fossilised remains. But we are discovering more all the time. About 50 new dinosaurs get named every year! It is also very likely that there were dinosaurs that lived that we will never know about because none of their bones or remains were fossilised.
How did the dinosaurs become extinct? – Vincent, 8 and Lucy, Grade 3
Scientists believe that the dinosaurs became extinct because a large meteor hit the earth around 66 million years ago. This would have caused lots of rock and dust to fly into the air causing it to turn dark for a long period of time (months to years), as well as cool the temperature of the earth. There is a crater in Mexico that supports this theory.
There were also a lot of volcanic eruptions happening and most scientist believe the eruptions would have also played a part in making the world colder and darker. Dinosaurs were not the only animals that became extinct at this time. Lots of plants, and other animals like fish and insects, also died out.
How are some old animals extinct, but some are not? – Destino, 9
Animals, or species, can go extinct for many reasons. Some things that can cause extinction are loss of the species’ habitat, climate change, competition with other animals or a reduction in the animal’s food supply. If these changes happen too quickly and the species cannot adapt to the new conditions (e.g. find a different food, move to a more suitable area to live), these animals become extinct. Sometimes the animals will be able to change and adapt to these challenges and survive.
Species go extinct all the time due to natural causes and sometimes many go extinct all at once, like the dinosaurs, in mass extinction events. There have been 5 mass extinctions in the history of the earth where up to 95% of species of animals and plants died out, but some always manage to survive, and repopulate the world.
Why do some people say dinosaurs went extinct due to a volcano while other people say they went extinct from an asteroid? – Sadie, Grade 3
The only way to know for certain why the dinosaurs died would be to go back and see what happened but unfortunately, we don’t have a time machine yet! So, we have to make the best guesses we can based on the evidence that we can find.
Here is what we know:
- We know which rocks we find dinosaur skeletons in, and we know how old they are. On top of this, we find rocks that are made during a meteorite impact – and we have a meteorite crater in Mexico that would have made these rocks. Then in the rocks created after the meteorite, there are no dinosaur skeletons. This is pretty good evidence that the meteorite did something to wipe out the dinosaurs.
- We also know that there was a lot of volcanic activity going on just before the meteorite, and just after. We can test the age of the rocks to find out when they were made. This amount of volcanic activity would be changing the climate, and this wouldn’t have been good for the dinosaurs either.
Looking at all the evidence, some scientists think it is option 1 is better, and some think option 2 is better. Some people even think that both of these events could have played a part in the extinction of the dinosaurs! I guess we won’t know for sure until someone invents a time machine.
Lizzie Lieschke is a PhD student and scientist studying why people get sick with cancer. She is researching how one of our genes protects our normal cells from becoming cancer. She hopes that by gaining more knowledge into how this gene works, we can make our current treatments for cancer more effective.
Lizzie has always had a passion for learning about the natural world. In Grade 1, her teacher suggested she should become a palaeontologist, and when she came back from a holiday, her sister told her she needed to take more photos of people than of rocks! At university Lizzie had a hard time deciding on which science she liked best, so she tried to do them all, by taking subjects in biology (animal, human and plant), geology, climate science, and chemistry. However, when she had the opportunity to work in a cancer research lab over the summer, she found this was what she was meant to be doing. She loves how as a scientist you are constantly learning, and that what we do aims to benefit others.
Team WEHI Relay for Life 