Name: 謎に包まれたTレックスの進化の謎に迫る (We’re Closer to Unravelling the Mysterious Evolution of the T. Rex)
Uploaded: 2021-01-14T09:58:41.000Z
Duration: 5 min 37 s
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Just how did the Tyrannosaurus rex get from oversized chicken to the colossal beast we

Well, we’re still digging for the answers.

Outside the confines of Jurassic Park, real-life scientists are always updating our ideas about

what dinosaurs may have looked like, and we’re constantly being surprised by their findings.

Like these brand new digital reconstructions of what baby T. rex’s may have looked like,

giving us new insight into their life cycle.

And beyond our curiosity about their beautiful exterior, related research has just revealed

that an early, ancestral species of T. rex was actually tiny!

Turns out, the iconic T. rex is an enigmatic animal to understand.

To get us a little more situated in this story we talked with Mark Norell, who’s been working

on understanding the details of dinosaur life for his whole career.

He and his team have created digital reconstructions of T. rex hatchlings, and guys—they’re

Mark Norell: “T. rex is kind of important because it's really an anomalous animal.

There's nothing else really like it at all.

And now that we're starting to get enough specimens of it that we can actually take

and really understand quite a bit about things like its growth, things like that ... Habits,

Most dinosaur specimens we only have one specimen of, or most dinosaur species.

But certainly with T. rex, we have 46 pretty well preserved specimens now.”

Until recently we didn’t have that much info about how the T. rex became the T. rex.

We knew they were a top end predator for about 15 million years up until their extinction

But when we try to go backward, before their mighty reign of terror began, there’s about

a 70 million year gap between giant T. rex and a medium-sized, primitive T. rex ancestor

we’d been able to unearth from the Jurassic period.

There was just nothing in the fossil record to indicate to us how, when, and how fast

T. rex went, in the words of one paleontologist, ‘from wallflower to prom king’.

So the chances of becoming a fossil are very, very, very, very, very small.

Chances of being a well preserved fossil is even much, much, much, much, smaller.

So we're working with not only a poor record, but a record which is flawed, also in the

sense that small animals don't preserve as large as big ones.

However—new fossils just unearthed in Utah are helping us put together the pieces.

These specimens are now thought to be the oldest Cretaceous tyrannosauroid remains ever

discovered in North America, and surprise!

They’re the much smaller and faster ancestor of the huge, lumbering T. rex we know and

This tiny ancestor of goliath is called Moros intrepidus, which cheerfully translates to

It took this team 10 years of incredibly persistent excavation to find this key organism, helping

us not only piece together T. rex lineage, but also give us a sense of where they lived

and how they migrated through an ancient earth.

This update to the fossil record now tells us that at some point, the T. rex must have

made the journey from Asia, the home the very primitive tyrannasoid fossils we’d found

previously, to North America, where we’ve found this new in-betweener.

In addition to improving our understanding of where the T. rex came from and how it evolved

over time, we’re also starting to revisit how they grew up.

What happens in between a baby T. rex hatching and the full adult?

Mark: “I mean it grew to adult size in about 19 years, which is pretty remarkable..."

So that T. rex could grow to its immense size, for a while it was growing over two kilograms

a day for quite a while during its lifetime.

As babies, the little stumpy T. rex arms were more proportional to their body size, letting

them hold on to wriggling prey, like their smaller tyrannosauroid ancestors.

But as they had to pack on more and more weight even faster as they rose to prominence, more

of that development went to the head and neck, specially designed to brutally crush their

The past ten years have been full of advancements to the computational and scientific tools

paleontologists use to analyze fossilized remains.

Techniques like synchrotron radiation and Raman spectroscopy represent non-invasive

imaging that let us see how the animals grew, to be able to see and count the layers of

Mark: "So on a computation and technology side really a lot of has changed.

And it's changing really quickly now, just as we speak."

Advancements in both excavation and analysis are continuing for the T. rex niche of this

field and paleontology in general—we’re starting to look at the fossil record in new

ways to help us gain a deeper understanding of well, everything.

From the origins of these species to what they looked like, what they ate, how they

interacted with each other, even what the ancient atmosphere was like ...there’s just

a wealth of information out there waiting to be dug up and discovered to tell us more

about our world and understand how we got to today.

Might as well start with the T. rex, huh?

While we won’t be bringing dinosaurs truly back to life any time soon, the American Museum

of Natural History is putting on quite the show with their T. rex recreations so if you’re

in town you should check it out, or check them out online at the link in the description.

Let us know what your favorite T. rex fact is in the comments, and make sure you subscribe

to Seeker to find out what paleontologists will unearth next.

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謎に包まれたTレックスの進化の謎に迫る (We’re Closer to Unravelling the Mysterious Evolution of the T. Rex)

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