Name: 从迪诺斯陷落到人类兴起（From the Fall of Dinos to the Rise of Humans）
Uploaded: 2021-04-30T12:38:05.000Z
Duration: 13 min 1 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Over the past several months, we've taken you on a journey through geologic history, one

If you haven't been on that trip with us yet, those videos, they're all in a playlist down

And by now, you're probably tired of hearing us tell you that you're related to all of

these bizarre organisms that look nothing like you.

Like, in the Mesozoic Era, we introduced you to the Megazostrodon, a little insectivore that

lived among the dinosaurs as one of the earliest known mammals.

At least that's a mammal, so you can see the connection, right?

It lived in the era before the Mesozoic, in the Paleozoic.

It's not our direct ancestor, but it was a stem mammal, part of the group of animals

that descended from reptiles to give rise to mammals.

And when you look at it, well … it's not exactly like looking in a mirror, is it?

By the time we follow our lineage back even farther, to LECA, the ancestor of all

eukaryotes, and LUCA, the single-celled ancestor of everything that's alive today, we're

talking about forms of life whose lives and structures we can only speculate about.

But, now you've arrived at the Cenozoic Era.

And the Cenozoic is when many organisms took shapes and behaviors that you could actually

Most of the mammals and birds that you can think of appeared during this era.

And reptiles went through some surprising changes, but they eventually settled into

But perhaps more importantly--for us at least-

the Cenozoic marks the rise of organisms that look a lot

OK to be fair, if you traveled back to the start of the Cenozoic Era, 66 million years

ago, there would still be a lot that you would not recognize.

It was so warm that the whole world was full of tropical and subtropical forests, even

And for about the first 10 million years of the Cenozoic, the world was still recovering

from the K-Pg extinction event that wiped out the non avian dinosaurs.

This was the very beginning of the Paleogene Period, and the world was … kind of empty.

Along with the dinosaurs, almost all other large land vertebrates had vanished.

Many terrestrial plants were gone too, and in the oceans, the giant marine reptiles and

even most of the plankton had disappeared.

Because of this scarcity of life, during the first chapter of this period, known as Paleocene

Epoch, there were plenty of open ecological niches, and the surviving forms of life began

The last remaining dinosaurs -- birds -- had begun to diversify into some pretty familiar

For example, around this time, we begin to see the likes of Waimanu, a small, flightless

waterbird from New Zealand that's one of the earliest known penguins.

Likewise, in New Mexico, the appearance of Tsidiiyazhi tells us that the ancestors of

mousebirds, found today all over sub-Saharan Africa, were already on the scene.

Meanwhile, on the forest floor, some early, ungulate-like mammals began to take over.

At first, these mammals had it pretty easy, because there weren't many predators.

But plenty of insectivorous mammals had survived the extinction.

And it didn't take very long for some of them to start developing a taste for bigger

These were the creodonts, predators that first appeared in North America like the small,

kinda dog-like Galecyon as well as, Oxyaena, which looked more like a cat.

For a long time, scientists thought that these small meat-eaters were the direct ancestors

But in recent years we've learned that they were actually a separate lineage, one that

happened to converge on the same strategies and general body plans of the carnivores we

Now, other mammals made their homes in the trees, including some of the first primate-like

They first showed up in Europe and North America, and even though most researchers think they

weren't direct ancestors of primates, they can still tell us a lot about what the earliest

Purgatorius, for example, looks a lot like a rat.

But it had long, grasping fingers, useful for life in the trees, and wide teeth for

But like other plesiadapiforms, Purgatorius had claws instead of nails, and it was missing

one of the key features of a true primate — its eyes didn't face forward.

So, by the middle of the Paleocene Epoch, animal life was on the rebound.

About 55 million years ago, the average temperature on land went up by 5 to 8 degrees Celsius

This spate of global warming marks the transition to the next epoch, the Eocene, and it's

known as the Paleocene-Eocene Thermal Maximum, or PETM.

If you've seen our episode on this phenomenon already, then you know that we're not totally

It might've had to do with volcanic eruptions or melting methane ice on the ocean floor

that released greenhouse gases into the atmosphere.

Either way, as a result, a world that was already warmer today's started to get even

At the poles, lush ecosystems took hold, while parts of western North America became arid.

This was great for animals that thrived in the heat, like reptiles.

Well, this is when the world saw the biggest snake that ever lived.

Titanoboa slithered through South America during this hot spell -- all 13 meters of

it, about twice the size of a modern anaconda.

It feasted on fish but also crocodilians and, also anything else it could get its jaws

Also in the water were reptiles like the giant turtle Carbonemys, which, unlike our shelled

friends we know today, were about 3 meters long.

While all this was going on, some of the first true primates were appearing.

The tiny Omomyids for example, had grasping fingers with nails instead of claws, and giant

Then, about 49 million years ago, this warming trend shifted, and the world began its long

journey from a greenhouse to an icehouse.

The shift may have been caused, at least in part, by what's known as the Azolla event,

where massive amounts of the small, moss-like Azolla fern grew in the Arctic.