Dinosaur Dreaming

Common questions:
Dinosaur extinctions

Do you have any theories on how the dinosaurs became extinct?

There are many theories on the extinction of the dinosaurs, the most popular two are:

• A comet impact which hit the Earth about 65 million years ago
• Lots of volcanic eruptions which could have affected the Earth's climate.

What killed the dinosaurs? Did the Tyrannosaurus rex get greedy and eat everything or did a meteorite kill them?

We don't really know what killed the dinosaurs. It may have been a meteorite impact or lots of volcanic eruptions. Scientists are working on this question all over the world and maybe one day we will know the answer.

Were there other animals other than dinosaurs that became extinct when dinosaurs did?

Many of the animals alive when the dinosaurs lived became extinct at the end of the Cretaceous. No animal with a body mass greater than 5 kilograms, that we know of, survived those extinctions.

Is it possible that dinosaurs were snowed out?

One of the theories as to how the dinosaurs dies is that there was either a meteorite or comet impact, or lots of volcanic dust that blocked out the sun and cooled the earth. The dinosaurs, and most of the larger animals died out as a result of the cold that this caused.

When will we be able to prove how dinosaurs became extinct?

The only way we will be able to prove how dinosaurs became extinct is to spend a lot more time researching the dinosaurs and rocks from the end of the Cretaceous, or by inventing a time machine!

What proof of the comet was found?

The best proof of the comet that has been found is a large impact crater at Chicxulub, on the Yucatan Peninsula . Try looking this area up in an Atlas to see where it is!

How are you sure that they died that way?

We are still not certain that it was the impact that killed the dinosaurs, but as most went extinct about the time the impact occurred it is very likely.

If there was a major change in world environment how/why did anything survive?

Whenever there is a change in the environment, some species are better able to survive than others. For example, if there is a time when food is hard to find, animals like crocodiles and snakes that can survive for months without food are more likely to survive than those that need food every day, like us!

Is there any evidence to support Extra Terrestrials may have been the cause of the extinction of the dinosaurs?

We have not found any evidence to suggest that extraterrestrial beings caused the extinction of the dinosaurs, but, the asteroid that hit the earth 65 million years ago was certainly of extraterrestrial origin!

If the dinosaurs dies with an asteroid strike, why didn't other plants and marine creatures die too?

65 million years ago, when the asteroid hit the Earth, there was a mass extinction of many other animals, not just the dinosaurs. About 75% of all land species went extinct, and many marine species died off as well.

I think that a comet hit the Earth, caused an earthquake, erupted the volcanoes, and changed the climate - but the birds kept high enough to stay at the right temperature - What do you think?

It is most likely that the birds were able to fly to areas that were less affected by the impact, and could keep on moving, even across oceans to find food. The dinosaurs that were unable to fly were less able to find food.

Have there been any craters on the land that have had dinosaurs buried? If so, is that how people think that a comet killed all the dinosaurs apart from the birds?

An impact big enough to create a crater is also big enough to completely vaporise anything that is caught underneath it. The reason why we thing an impact killed off most of the dinosaurs is that only birds are found after the 65 million year impact. It is the dust and other stuff that got tossed up into the atmosphere that resulted in the extinctions.

Why is the end of the Era of the dinosaurs called the KT Boundary?

"KT Boundary" stands for Cretaceous/Tertiary Boundary, and is the boundary between these two periods of time. It is also the boundary between the Mesozoic Era and the Cainozoic Era. You can find out more about these time periods by looking up books on geology in the library.

Which dinosaur (reptile) was last to become extinct? How do you know this?

If you say that birds are dinosaurs, as we now think, then they are still going extinct today! Try looking up books to find out the story of the Passenger Pigeon, which went extinct in this century. There is a T. rex skeleton, found 1m below the KT boundary, that is possibly the last of the old dinosaurs to go extinct.

Wouldn't the teeth and bones rot over the years?

Teeth & bones are made up of hard materials like Calcium Phosphate, which does not rot! That is why when we find fossils, often all we find are the teeth and bones.

Volcanoes and Extinction

How far down is the lava?

There are places on the Earth's surface where lava comes right up to it, but usually it is between 8 km and 35 km below the surface.

How far does the crust go down?

The continental crust is usually between 35km and 50km thick, but can be as much as 100km thick. Ocean crust is much thinner, about 10km thick.

Why didn't the birds die from volcanic ash in the air slowing their flying?

Birds that fly through volcanic ash that has just erupted out of a volcano will die, because of the heat and the ash thickness. Birds that avoided thick volumes of ash would have survived.

Why are there plates in the earth?

The plates that make up the crust of the earth are formed when molten rock cools at the surface. They are separate plates because forces in the mantle (which is below the crust) drag them around on the surface of the earth in different directions.

Which volcano was the largest and most dangerous on Earth? What damage did it cause?

The biggest volcanoes ever would have erupted on the Earth's surface soon after the Earth formed, 4.5 billion years ago. There are no traces of these volcanoes left on the Earth as they have been eroded away. The largest volcano we know of in the solar system is Olympus Mons on Mars. The largest that we know of that is erupting on Earth at the moment is Mt Kilauea in Hawaii.

Why does the carbon dioxide, sulphur dioxide and halogens come out and not other materials?

Carbon Dioxide, Sulphur Dioxide and Halogens are not the only gases that come out of volcanoes. You also get other nasties like Carbon Monoxide, Hydrogen Sulphide, Hydrochloric acid, and Sulphuric acid. Volcanoes also give off water vapour.

Why, when you held up the two pieces of rock from the volcano, were they different colours?

The different colours of the rocks were because they are made up of different minerals. The light coloured rock has lots of quartz in it, while the dark coloured rock is made up of basalt (bluestone).

Was the Earth smaller before the dinosaurs lived on the Earth than now because of volcanic activities and plate tectonics?

The size of the Earth does not appear to have changed significantly even though new crust is being produced by volcanoes. This is because old crust is being recycled back into the earth at places like Deep ocean Trenches, where it then melts to make up more lava.

How did you know how deep the rocks came from?

We can tell how deep the magma came from that made the rocks by looking at the minerals in them. Rocks that contain dark minerals, like basalt and olivine, come from deeper in the mantle than rocks that contain light minerals, like quartz.

Why is lava a "yellow sort" of colour?

The yellow or red colour of lava tells us how hot it is! The hotter something gets the lighter the colour is. Red lava is cooler than yellow or white lava.

Why are the chemicals in the volcanoes under the water different from the chemicals in the volcanoes on land?

Underwater volcanoes usually contain lava high in iron and magnesium. This is because they come from deep in the mantle. Volcanoes on land can sometimes also contain these elements (like the ones in Hawaii), but more often have lava that contains more quartz and aluminium.

Could continental glaciers have created continents which we live on?

Continental glaciers are huge frozen masses of ice. They move slowly downhill across the surface of the continent, eroding away the surface of the continent beneath like sandpaper. They don't make up continents, they sit on them!

How close can you get to an active volcano?

How close you can get to an active volcano depends on how brave (or foolish!) you are, and also the type of lava it is spitting out! If the lava is runny, like in the volcanoes of Hawaii, you can sometimes get within 3 metres of it. If the lava is explosive, like Mt. St. Helens, you wouldn't want to get within 1km of it, or you may not come back to tell the tale!

How do you know what the inside of the Earth looks like right down to the core?

We know what the structure of the inner earth looks like by measuring the way that earthquake rumbles are transmitted from the original source of the earthquake through the solid earth and the less solid mantle and core.

How do you measure how old the rocks are?

There are a number of ways we can measure how old the rocks are, but for rocks made from lava the best way is to look at how much radioactivity they have. This can tell us how long ago they were formed, and is called "Radiometric Dating".

Why does a volcano erupt in certain periods of Earth's history?

Volcanoes have been erupting throughout most periods of the Earth's history (there are currently more than 35 active volcanoes right around the world), but at times there are more of them than others. This can be related to how the continents are arranged, and whether there are any large weak spots in the Earth's crust where lava can reach the surface.

How many volcanoes would have been active when dinosaurs lived?

Volcanoes have been erupting throughout most periods of the Earth's history (there are currently more than 35 active volcanoes right around the world), but at times there are more of them than others. We are not really sure yet exactly how many volcanoes there were during the time of the Dinosaurs, but near the time they went extinct there were certainly a lot of them in India. Maybe you will one day be the person who does the research to find out exactly how many!

Were there any volcanoes active in Australia when the dinosaurs became extinct?

We have no evidence of volcanic activity in Australia from 65 million years ago (when the dinosaurs became extinct). There were underwater volcanoes between Australia and Antarctica at that time, but none that we know of on the land!

Is digging around volcanoes the best place to look for dinosaurs?

Dinosaurs caught in lava (which is very hot!) would have been vaporised, not even leaving behind any bones. Dinosaurs caught in an ash fall (which is cooler) are more likely to be fossilised!

Can tektites only be formed by asteroids?

Tektites can be formed by any impact that is big enough to melt the rock it falls on.

Some dinosaurs are pictured as having horns. How do scientists know about this when horn and muscle tissue decays rapidly?

Horns do preserve, as they often grow on bony protrusions of a skull. If you look at the skull of a horned cow or goat you will see these bumps!

Are you sure that this [volcanic eruption] is the way they [dinosaurs] died?

The volcanic eruption is just one of a number of theories that have been put forward to explain the extinction of dinosaurs. We are still not sure exactly what happened!

What proof have you got that dinosaurs were killed this way?

We find no bones of dinosaurs (except birds) in rocks younger than 65 million years. We also know that there was a lot of volcanic activity happening just before this time, and we know from observations of volcanoes erupting today that they can have affects on climate. The climate often gets colder following big volcanic eruptions, and this may have made it hard for large animals, like the dinosaurs to survive.

How many types of dinosaurs were there?

In Australia there are more than 12 types of dinosaurs, and in the rest of the world there are more than 300, but more dinosaurs are being found every year!

Do you think they were killed by anything else?

Dinosaurs may have also been killed off by the impact of a large meteor that hit the earth about 65 million years ago.

How many times a year did volcanoes erupt?

Volcanoes have been erupting throughout most periods of the Earth's history but at times there are more of them than others. There are currently more than 35 active volcanoes right around the world. Some of them are erupting constantly, while others only grumble from time to time.

How many times would a volcano erupt before dinosaurs became extinct?

The extinction of the dinosaurs may have been caused by a whole lot of volcanoes erupting at once. A single volcano wouldn't produce enough dust or ash or gases to cause mass extinctions!

How many years have the dinosaurs been extinct?

Dinosaurs are not really extinct! They live on as birds, which are descended from the dinosaurs. However, the big dinosaurs, like T. rex and Triceratops went extinct 65 million years ago.

Would it be possible for people to travel inside a volcano?

It is not yet possible to survive the high temperatures that you encounter when taking a trip inside a volcano! However, if you could find a material that could survive the high temperatures (up to 1200 degrees Celsius) inside a volcano, AND keep it cool, then it may one day be possible to travel inside an active volcano! If you go to the western districts of Victoria there are some places where you can walk through tunnels left by old and cold volcanoes!

How would you know what it's like inside a volcano if it's too hot inside?

We can find out what it is like inside a volcano by studying old and dead volcanoes, and then comparing them to the hot active volcanoes. We can also take samples of the lava erupting from volcanoes and work out where it has come from in the Earth, as well as using radar and magnetism to map the shapes of volcanoes under the surface of the Earth.

How does the lava heat up?

The lava comes from deep inside the earth where temperatures are much higher. This is caused by the fact that even after 4.5 billion years the Earth still hasn't cooled down completely after its formation, and helped by heat produced by the breakdown of radioactive elements.

How many dinosaurs would have died out from volcanoes?

If the volcanic eruption theory is correct almost all of the dinosaurs died out as a result of volcanoes. The only ones still alive today are the birds!

If the Earth cooled down would that mean that the dinosaurs died out because they didn't have enough heat?

One theory as to why the dinosaurs died suggests that it was because less heat from the sun was able to get through the atmosphere to warm the surface of the earth. As well as cooling the Earth down, this would also affect the growth of plants, and many animals would starve.

Would the temperature get hotter if it was a large volcano - and how long would it take for the ash to settle?

The temperature of a volcano is more controlled by the rate at which its lava flows out to the surface than by the size of the volcano. The time it takes for ash to settle depends on how high into the atmosphere it is blasted when the volcano erupts. Ash from the eruption of Mt Pinatubo rose more than 40km into the atmosphere and is still affecting the weather today, more than 3 years after its eruption!

How many centimetres of rock would have made up a year?

The amount of rock made in one year depends on the amount of ash or lava a volcano produces in that year. Some only give out small amounts, and you may get less than 1mm in a year, others produce huge amounts and you may get more than 1km of new rock in a year.

Are there any countries without volcanoes? And if so, why wouldn't the dinosaurs still be there?

Every continent has volcanoes, but not all countries have them. However the dust and ash that volcanoes give out do not stop at the borders of countries! The dust from a volcanic eruption will travel high into the atmosphere and cause problems to life right across the Earth!

Which were the animals that survived when the volcanoes erupted?

The main groups of animals that survives the volcanoes that erupted 65 million years ago were the mammals, birds, reptiles, fish, and many other varieties of snails, slugs and insects.

Do some of the poisonous gases still exist around the atmosphere?

Volcanoes that are erupting right around the world today are producing poisonous gases. If you become a vulcanologist (a person who studies volcanoes) there will be times you have to wear special breathing equipment to allow you to get close to them without being killed off like the dinosaurs.

Does alien life have anything to do with volcanic eruptions?

We have no evidence that aliens have ever visited the Earth, or had anything to do with volcanic eruptions or the extinction of the dinosaurs!

Do you believe in alien life forms?

It is possible that life exists on other planets. This year there was evidence found that Mars may have once had bacteria-like life forms (but none big enough to build spaceships!). With the billions of billions of billions of stars out there it is almost certain that we are not the only life in the universe! Space is an awfully big place - if we are the only lifeforms in it, isn't that and awful waste of space?

Do you regard alien life forms as extraterrestrials?

Alien life forms would be extra terrestrial! Extra = out, terrestrial = earth, so by definition, any life that has not come from this planet is extraterrestrial.

If it was noxious atmosphere why did some life forms not die?

Some creatures are more sensitive to gases than others. Miners up until a few years ago used Canaries to check for gases in underground mines, as they were more sensitive to gas than people were. If the canary fell off its perch, the miners left the mine immediately!

Which Australian dinosaurs were affected by the mass kill at the end of the Cretaceous?

All the Australian dinosaurs appear to have been affected by the mass kill at the end of the Cretaceous. We have found no dinosaur bones in rocks more recent than then!

Why did the earth tissues move?

The plates (tissues?) that make up the crust of the earth are formed when molten rock cools at the surface. They are separate plates because forces in the mantle (which is below the crust) drag them around on the surface of the earth in different directions.

Why did some animals survive while others were killed off?

The most likely reasons for animals to go extinct is from a change in their environments, like a drop in temperatures. If the temperature drops, some plants can't grow. If the plants don't grow, herbivores starve. If the herbivores starve, carnivores starve! Animals that are able to go for long periods without food, like snakes and crocodiles, or can hibernate, like early mammals, can avoid this time of hunger.

How come some lava rocks are heavier than others?

The weight of a rock depends on the minerals it is made of, and how close together those minerals are packed! In some lava rocks, gas bubbles form as the rock cools, making it lighter - pumice, a volcanic rock, can float on water!

What's the temperature of lava?

The temperature of lava depends on its composition, If it is the sort of lava that forms in undersea volcanics, or island volcanics it is about 1200 degrees Celsius. If it is the sort of lava that forms on continent volcanoes it is cooler, only around 800 degrees Celsius. (Your oven at home can only go up to about 250 degrees Celsius!)