I'm paleontologist Hans Sues.

Today I will be answering your questions from Twitter.

This is Dino Support.

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@TokageSetsuna asks, what's the scariest dinosaur?

I think the scariest looking dinosaur

would've been Spinosaurus, simply because it had

this huge sail on its back.

But I think here in the United States

the T-Rex is definitely the people's favorite.

Here's part of a T-Rex tooth.

The largest tooth, including the root,

gets up to about seven or eight inches in length.

These cutting edges are serrated, like a steak knife.

T-Rex ate the whole prey.

We have fossil droppings of T-Rex,

and they show us that it ate the meat and the bones.

It crunched up the bones, much like

some big crocodiles do today.

@RickyDelz asks, scientifically and historically speaking,

how do we know what dinosaurs sounded like?

Surely the sounds the movies have taught us

are just guesses, no?

Well, indeed they are just guesses.

In fact, it's quite likely that dinosaurs were much quieter

than people give them credit for.

Birds sing, but most reptiles don't make much

in the way of sounds, except for hisses and grunts.

So we think that dinosaurs would have done things like that,

but certainly not this lion roar

that Hollywood wants us to believe.

Ev4n2k4 asks, when I die and go to heaven,

first thing I'm asking God is

what did Jurassic Park get wrong?

Jurassic Park was made as an entertaining movie,

not as a science documentary.

The star of the movies are the raptors.

Here is an actual skull of an adult Velociraptor.

The filmmakers decided that it looked too puny,

and they needed something bigger.

Strangely enough, shortly after this was filmed,

people found a really gigantic raptor out in Utah.

And since then, other giant raptors have been found

in South America and in Asia.

So there were giant raptors around,

but they were, in fact, much bigger

than the ones in the movie.

The movie claims that T-Rex

could only detect prey by motion.

In fact, when we study the brain case of a T-Rex,

we find that it had very large olfactory bulbs,

which are the part of the brain

that picks up information from the nose.

It had a very large opening for the optic nerve,

which is the nerve that transmits information

from the eye to the brain.

And it had a very complicated inner ear

that allowed it to hear at least the wide range

of low frequency sounds.

So it would've smelled the actors in front of its snout,

and it would've been a very short movie, indeed.

@emohairawsten, how did the asteroid kill every dinosaur?

Doesn't an asteroid hit one general area

rather than the entire world?

The asteroid theory is a very flat earth theory.

There's no flat earth.

The earth is a sphere.

What happened was when the asteroid happens to impact,

it released the equivalent of 100,000,000

mega tons of energy.

And this basically melted this huge asteroid,

which was six miles in diameter.

And this sent up a gigantic cloud

of glowing material up into the atmosphere.

This would spread around the world.

We see this even today.

When a volcano erupts, volcanic dust

sweeps all around the world.

Imagine a world where suddenly

it's raining drops of molten glass.

That's what was happening.

And so basically every larger animal at that point died.

And that's why the dinosaurs were wiped out,

probably within a matter of hours,

at most, a matter of days.

@laurenbergerr asks, how do they know

what color dinosaurs were?

For many years, we really had no idea

what color dinosaurs had.

In fact, people assumed that like many

of the modern lizards, snakes, crocodiles, turtles,

it would've been greenish brown,

and that's what you see in all of the old dinosaur books.

However, in recent years, thanks to some

remarkable discoveries in China,

we actually found out what some dinosaurs looked like,

and it was a real revelation.

We found that some of the little feathered dinosaurs

actually had color patterns as vivid

as those in modern birds.

There's a dinosaur called Caihong,

and it had beautifully iridescent feathers.

So it would've looked like a big starling with nasty claws.

So the dinosaur world was far more colorful

than we were previously thinking.

@t6lly asks, so why were dinosaurs so big back then,

but now animals are small?

Scientists go.

A lot of dinosaurs were big,

but there were also small dinosaurs.

In fact, there's one dinosaur

that's barely over two feet long.

Do you live in an environment where it's advantageous

to be big for your particular mode of life?

And there's some places on earth

where the rules are reversed.

Often on islands, generally large animals become dwarfs.

About 15,000,000 years ago, a gigantic hedgehog

lived on an island, and what's now Italy.

In other parts of the Mediterranean,

there were tiny elephants running around

that would've actually been nice little pets

if we had been around at that time.

Godstiddies asks, how many species of dinosaurs are there?

I want to know all of them.

Right now, there are about 1,100

described species of dinosaurs, other than birds.

Even very conservative estimates

put the number much higher, anywhere between

2,000 and 5,000, and there may have been even more.

One important thing to keep in mind is

we are much closer in time to a T-Rex

than the T-Rex was to a Stegosaurus.

We now have classified this myriad of species

by looking at various parts of their skeleton.

The most obvious part of the skeleton is the hip region.

When you look at the T-Rex over my shoulder here,

you can see a hip girdle that has three bones

with the front bone, the pubic, pointing downwards,

whereas in the so-called bird hipped dinosaurs,

which is unfortunately a misnomer

since they have nothing to do with birds,

you get a hip region that has

the pubic bone pointing backwards.

There are many more subtle anatomical differences,

but basically there are two large groups of dinosaurs.

The lizard hipped dinosaurs, also called Saurischia,

and the bird hipped dinosaurs, called Ornithischia.

@lustclouds asks, why did T-Rexes have little arms?

That does not sit right with me for a dinosaur.

T-Rex had really small, but very powerful arms,

and you can see this here on our pride and joy.

Nobody really knows why T-Rex has tiny arms.

It has been calculated that the arms

were still strong enough to lift up to 600 pounds of weight.

Earlier relatives of T-Rex still have longer arms.

Other predatory dinosaurs actually get

increasingly longer arms, which eventually

become wings in birds.

@solarhwngs asks, since when were pterodactyls

not dinosaurs?

Since ever.

Dinosaurs and pterodactyls are related,

but pterodactyls have nothing to do with dinosaurs.

They have an early common ancestor,

but they diverged in their evolution quite dramatically.

Pterodactyls became flying creatures

with wings very different from those of birds,

whereas dinosaurs were mostly land dwelling animals,

and only a few forms later on evolved into birds,

which have very different looking wings.

@TrooperSnooks asks the question of the day.

Why did the early mammals and birds and fish,

like sturgeon, et cetera, not become extinct

when the dinosaurs did?

That's a very good question, and, in fact,

it's one of the great mysteries of paleontology.

It's basically different life strategies.

Small animals can hide.

A lot of small animals are also able to go without food

for long times, whereas a large animal cannot.

Most dinosaurs went extinct,

and only one group of dinosaurs, birds, survived.

Birds, as I just said, are dinosaurs,

because they descended from small, meat eating dinosaurs,

just like we are primates, because we descended

from other kinds of primates.

We now have a beautiful series of fossils

documenting all of the stages between

little predatory dinosaurs like that,

and birds that would've been recognizable

as a bird to anyone alive today.

It's very rare that you get such a nice continuation

of fossils between one group and a group

that it gave rise to.

@TrieboldPaleo, who would win in a fight?

Camarasaurus or an Anatotitan?

An Anatotitan and Camarasaurus lived at

very, very different points in time.

An Anatotitan at the end of the Cretaceous period,

about 66 to 68,000,000 years ago,

and Camarasaurus about 150,000,000 years ago.

My money would be on the Camarasaurus,

simply because Camarasaurus got a lot bigger.

Both, though, are harmless plant eaters,

and so I don't think they would've really fought each other.

@Harry_Buttcheek asks, what was the climate

when the dinosaurs roamed?

The world in which dinosaurs lived

was generally a fairly warm one,

however, at high latitudes where the sun would disappear

for months at a time, it would've been quite cold,

and we actually have even evidence from fossil soils

that there were permafrost soils in some areas,

yet dinosaurs lived there.

Dinosaurs really could cover almost any environment

that you can imagine.

We know dinosaurs that lived essentially

under sub polar conditions.

We know dinosaurs that lived in really tropical regions.

We know dinosaurs that lived in deserts.

So basically in a warm period of geological history,

they were everywhere.

@Udonis_Haslem69 asks, how are fossils a thing?

Don't those, beep, just disintegrate?

Well, fossils are a thing.

They're real, three dimensional objects.

Here's a limb bone of an ostrich mimic dinosaur

that's about 90,000,000 years old.

Basically what happens is after death,

minerals infiltrated this bone

from the ground water around it,

and they contained a lot of iron,

that's why it has this yellowish brown color,

and gradually filled in all of the spaces in the bone.

Sometimes the actual bone is still pretty much preserved,

but in most cases, the bone has changed

just ever so slightly so that it's no longer possible,

for instance, to extract biomolecules like DNA from it.

@arc315 asks, were dinosaur feathers dinosaur scale,

or did they have a lot of bird sized feathers?

The really gigantic dinosaurs by and large

did not have feathers.

We only know one really large Tyrannosaur from China

that lived in a very cold environment and had feathers.

Most of the dinosaurs that we know that had feathers

were animals up to maybe five or six feet in length,

and they had bird sized feathers.

And we know this because the bones

have little bumps on them, and you can see them

when you take a chicken apart.

They're called quill nodes, and that's where the large

flight feathers in a bird insert.

@mr_soak asks, idea, what was the smartest dinosaur like?

Would they have used tools?

Built shelter?

How much could they understand about the world?

Some of these little predatory dinosaurs

have really large brains.

They have a bulging area here,

much like you would see on a bird skull.

So these little dinosaurs probably had cognitive abilities

similar to those that we see today in hawks, owls,

and particularly in crows and ravens.

Crows and ravens have repeatedly shown

their ability to solve relatively complex problems.

And some birds have minimal kinds of tool use as well.

And something like that is not beyond the possibility

for these early dinosaurs as well.

@biotchfromhell asks, when did the first humans discover

that there were dinosaurs?

I really want to know how we first figured out

giant, giant, giant dinosaurs roamed the earth.

The first record that we know of a definitive dinosaur

is from the 17th century in England

when Robert Plot described a part of a thigh bone.

He didn't know what to make of it.

He compared it to giants of legends.

President Thomas Jefferson couldn't conceive of the fact

that animals had gone extinct, even though he found fossils

of extinct animals on his estate in Virginia.

He thought that these animals still existed somewhere

alive out West, and that was one of the reasons

he sent the Lewis and Clark expeditions out.

The Smithsonian got into the dinosaur business

early in the 20th century, and here's an old photograph.

This was taken the 1930s.

It's an excavation in progress,

and you see people here chipping out large blocks of rock

that have bone in them, and then are taken back

to the laboratory where the actual excavation begins.

We can glue it back together, clean its surface,

and ultimately it's ready for study and exhibit.

@HalfPassStoned asks, who comes up

with these dinosaur names?

What if a dinosaur were named Hank?

Why do you gotta make names so complicated?

The scientists who describe the dinosaurs

come up with the names.

Each animal has a genus and a species name.

And in the case of dinosaur names, it's the same.

It's Tyrannosaurus Rex.

In that case, it's actually one of the best names

ever chosen for a dinosaur, because the researcher

wanted to portray it as the tyrannical creature

that ruled its ecosystem, and because of its big size,

it was called Rex, which means king.

I've been very fortunate that somebody

named a dinosaur for me.

There's an animal called Hanssuesia,

which is a little boneheaded dinosaur,

which I take as a backhanded compliment

that I am boneheaded.

But it's a nice thing, because it immortalizes you.

@MarkBessen asks, how did T-Rex sleep?

Curled up roosting like a chicken?

Asking for a friend.

T-Rex presumably crouched, down just like a lot of birds do

when they're resting.

However, we actually have found dinosaurs

that were preserved in burrows where they presumably

were sleeping, or at least hanging out.

And some of them are kind of curled up.

@PaulGarciaNBA asks, how did the Brontosaurus

weigh 23 tons when it only ate plants?

You have to imagine that these dinosaurs

probably spent every waking minute eating.

The other reason that Brontosaurus is so big is

if you eat plants, you have a big problem.

Much of the plant food that animals and people eat

is made out of cellulose.

And so you need a very large gut to accommodate bacteria

and other microorganisms that can break

the cellulose down into fatty acids and in sugars,

like glucose, that the host animal can actually digest.

So in order to be a full-time plant eater,

you need a really large gut.

@alanilagan asks, were dinosaurs cold blooded

or warm blooded?

I genuinely have no clue.

Well, this has been a matter of scientific debate

for many years, but we now think

that dinosaurs have a mixture

of body temperature strategies.

The little feathered dinosaurs were warm blooded,

much like the descendants of birds,

but some of the really large dinosaurs actually

were either warm blooded or cold blooded,

because when you have a really large body mass

and live in a warm climate,

it doesn't really matter either way.

@R3ik0_X asks, how long did the dinosaurs live for?

Weren't they around for 1,000,000 years or something?

Well, dinosaurs as a group first showed up

230,000,000 years ago.

Most dinosaurs went extinct 66,000,000 years ago,

and of course the descendants of birds,

who are also technically dinosaurs,

exist to the present day.

We don't know much about individual dinosaurs life span.

In the case of the T-Rex, we have found now

that the oldest known and largest T-Rex

was only about 30 years old when it died.

These dinosaurs grew apparently at an amazing pace

early on, and died young and left, in some cases,

a good looking corpse.

So those are all the questions for today.

I really enjoyed seeing all of them,

and seeing the level of interest in dinosaurs out there.

Thank you for watching Dinosaur Support.