Name: あなたの感謝祭のテーブルの上の恐竜 (The Dinosaur On Your Thanksgiving Table)
Uploaded: 2021-01-14T07:58:38.000Z
Duration: 10 min 37 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

未来進行形

This holiday season, I bet many of you are going to be sitting down with family and friends to celebrate.

And I bet a lot of you are going to be eating some nice delicious… dinosaur!

That's what we're going to talk about today.

Today I'm here with my friends Anna Rothschild who makes Science Magic Show Hooray! at The

Washington Post, and… fun fact, she's 25% mashed potatoes.

And Dr. Shae Montanari, who is not only a pumpkin beer aficionado, but is a dinosaur expert extraordinaire.

We have all heard that birds are dinosaurs, but what exactly does that really mean?

So the way that we can even tell that anything is related to something else is through looking at

their anatomy and what kind of characteristics that they share.

These are called synapomorphies, traits shared by two or more groups of organisms, and derived

Like how humans and chimps both have opposable thumbs.

So, there's different kinds of dinosaurs and we can look at the characteristics of

birds to find out exactly what kind of dinosaurs they are.

There's actually lots of clues preserved in their bones that show that they are very

closely related, and that birds are actually dinosaurs.

And we're gonna find those today, with this!

So, we couldn't get a turkey, it's not quite Thanksgiving yet.

But everything we show you we promise you can do at your holiday table with the people

you're celebrating with, and explain to them the science of why you're eating a dinosaur.

VO: In the 1860s, scientists unearthed the most famous feathered dinosaur fossil: Archaeopteryx.

Early defenders of evolution like Thomas Henry Huxley began to suggest that these extinct reptiles were

so similar to birds, they must be related.

But the idea didn't really catch on until the 1970s, when new fossils filled in more

empty branches on the dinosaur family tree…

VO: About 250 million years ago, a group called Archosaurs split into Crocodilian reptiles, and Dinosaurs.

And a lot of evolution has happened since that split.

Ok, so there's two groups of dinosaurs, and that's the Ornithischian and the Saurischian dinosaurs.

And that split happened about 240 million years ago.

And the way we know that birds belong to the Saurischian group is mainly because of their hands.

Birds actually DO have hands, they just don't really look like hands anymore.

So if you've eaten a chicken wing, or at least you know held on to a chicken wing, you've been shaking hands with a chicken!

Can we dig into this chicken and check it out?

So these are like the original chicken fingers!

-you're doing it completely differently  -So that little skinny part of the wing, at

That little nubbin, is the finger of the chicken, that's gotten super reduced.

I accidentally broke off the very tip of the bird finger, but here is like, the second digit.

Joe, I'm going to let you hold that as well!

That's first digit. This is second digit. And third digit.

The length of the three bird fingers inside a wing narrows down which group of dinosaurs birds descended from

The second finger is longest in birds and in Saurischian dinosaurs.

That's a big way we know that birds belong to the Saurischian group as opposed to the Ornithischian group.

So birds are Saurischian dinosaurs, but are all Saurischian dinosaurs birds?

So even within Saurischian dinosaurs, as we're walking up this dinosaur family tree, there's

another group that branches off and we can tell which one birds are a part of, and it's the Theropod dinosaurs.

And the one bone that is the biggest clue of Theropod dinosaurs is something that you've

probably played a little game with after your thanksgiving dinner: The wishbone!

Does it serve a purpose for flight or for something else?

Besides helping all their dreams come true, the furcula is actually support for the flight muscles.

A wishbone, or “furcula”, is actually a bird's collarbones, but instead of two

separate collarbones like we have, theirs is fused into one.

Wishbones have only been found in birds and Theropod dinosaurs, like Allosaurus, and they

draw a clear line from those extinct creatures to our modern feathered friends.

Ok let's get this wishbone out in one piece.

and all dinosaurs in this part of the tree also had something like this?

We've found a furcula in most Theropod dinosaurs' fossils that we've found around the world.

VO: Fossil wishbones are one of the most important pieces of evidence we have that birds descended from Theropod dinosaurs.

So actually one of the similarities between birds and theropods, and how we know that

birds are theropod dinosaurs, is inside their bones.

This is another one of those tibiotarsus bones…

Drumstick bones, and I have channeled all of my rage and broken this one in half, and

look inside, and you can see that the walls of the bone is very thin and basically hollow.

So when people say that birds have hollow bones, that's what they mean.

There's very little spongy bone on the inside, and there's a very thin wall, which makes

Theropod dinosaurs had these hollow bones too.

So did that help them be more agile, you know, go in for more Jurassic Park type kills?

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あなたの感謝祭のテーブルの上の恐竜 (The Dinosaur On Your Thanksgiving Table)

specific

completely

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