♪ Greetings, birdbrains!
It’s me, Dino!
Jessi asked me to visit the Fort today to talk
about my favorite subject in the whole
wide world: dinosaurs!
you’ve probably heard before that dinosaurs the
– the giant reptiles that walked the Earth millions of years ago – are extinct.
That means they’re not around anymore.
And it’s true that most of the dinosaursdid go extinct.
But not all of them.
65 million years ago, big changes were happeningin the world.
Lots of volcanoes were erupting,
and then a giant asteroid collided with Earth, in a
For a long time after that, the world was very dark,
then very cold, and then very hot.
With no sunlight, a lot of the plants died,
so the dinosaurs that ate plants didn ’ t
have enough to eat, so many of them died,too.
That meant the dinosaurs that ate other dinosaurs didn ’ t have enough food either,
and a lot of them went extinct.
So, it was a really hard time to be a dinosaur!
但是一些恐龙很聪明 有足够的本领挺过去 因为
But some dinosaurs were clever and talented enough to tough it out. Because,
their bodies had just the right
adaptations — certain traits that helped them survive these big changes.
The dinosaurs that survived had dinosaur babies,
and soon their babies had their own little babies,
all the way down the family tree.
And the animals that came from them are still living here on Earth!
We call them … birds!
意味着像我 迪诺 一样的鸟类
That means birds like me, Dino,
are descendants of dinosaurs, and dinosaurs are my ancestors
— like my great-great-great-greatgreatgreatgreat-grandparents!
I’m part of the dinosaur family tree!
And since birds are part of the dinosaur family,
I ’ m not just a descendant of a dinosaur
… I am one!
So the dinosaurs… live! Now,
how do we know that birds are relatedto dinosaurs? Well!
We have lots of clues – specifically, from theropods,
a group of two-legged dinosaurs
that also included velociraptors and Tyrannosaurusrex!
Hundreds of millions of years ago,
way before the earliest birds appeared, dinosaurs were
developing lots of birdlike adaptations.
Theropod dinosaurs especially,
started to have a lot of birdlike traits that would later
help birds take to the skies!
Lots of dinosaurs – even dinosaurs
that didn ’ t become birds – had feathers.
Some of these feathers were more like little hairs,
which probably helped dinosaurs keep warm.
But some types of theropods wound up with bigger,
fancier feathers, and even wings.
Before there were birds,
fancy feathers might have been used to keep these dinosaurs and
their eggs safe and warm, or to communicatewith other dinosaurs.
But even though bigger theropods, like some kinds of tyrannosaurs,
had feathers, they
couldn’t just flap their arms and fly around.
To really be able to get off the ground, you need wide,
powerful wings, and a small body.
While lots of types of dinosaurs were becoming gigantic,
some theropods – including those
that eventually gave rise to birds – weregetting smaller.
So lots of dinosaurs already looked and moved a lot like birds.
And some of the theropod dinosaurs were becoming more like birds all the time!
变得越来越小 逐渐长出翅膀 进化出喙而不是牙齿
Getting smaller, growing wings, and developingbeaks instead of teeth.
Over millions of years,
all the pieces of the bird puzzle were coming together, one
大约一亿五千万年前 最早的迪诺 也就是鸟类出现在天空中
By about 150 million years ago, the earliest dino-birds were in the air.
Some of them could fly,
but looked very different from the birds we know today.
And some didn ’ t fly,
but had a lot in common with today ’ s birds!
Millions of years later, when that asteroid hit Earth,
and the volcanoes started to erupte,
and everything started changing, some dinosaurshad a hard time surviving.
A lot of the big ones, like T-rex,
were so big, they had trouble finding enough food to eat.
But the most birdlike groups
of theropods were very small – only about 1 kilogram,
or as heavy as a pineapple.
That meant it was easier for them to survive
on less food and to find places to live.
And because they were so small,
these early birds were also able to use their wings to
Not only did some of these flying dinosaurs survive … they really took off!
We have more than 10,000 types of birds aroundtoday!
So the next time you see one of us feathered friends flying around,
you ’ ll be able to
指着它 然后说 “嘿 看 一只恐龙”谢谢加入我 朋友们
point to it and say, “Hey, look! A dinosaur!” Thanks for joining me, birdbrains!
Do you have questions about birds, or dinosaurs, or anything at all?
Ask a grownup to help you leave a comment below,
or send us an email at kids @ scishow.com.
See you next time!