This episode is brought to you by the Music for Scientists album,
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To start listening, check out the link in the description.
[♪ INTRO]
Tyrannosaurus rex has been everyone’s favourite dinosaur
for more than a hundred years.
And a century of study has given us new insights into what this terrible lizard
looked like, and the role it played in the Cretaceous world.
But even though we’re learning more all the time,
the popular image of T. rex seems to be stuck in the past.
Now, new techniques and new fossils are turning our thinking about
these fearsome predators on its head.
It’s time to meet the real T. rex!
Skeletons of this gigantic dinosaur were first discovered back in the early 1900s.
The first paleontologists that studied them saw rows of deadly sharp teeth
and long powerful legs, and rightly concluded that they belonged
to a fearsome predator.
This dinosaur, Tyrannosaurus rex, lived about 68 to 65 million years ago,
at the end of the Cretaceous period.
It was one of the biggest land predators of all time.
Since then, T. rex has been immortalized in books,
films, and cuddly plushies, as the iconic dinosaur.
But if you ask anyone to actually draw a T. rex from memory,
they’re a big chance that most will draw it Godzilla-style
upright and balanced on its tail,
with its little arms tucked uselessly next to its chest.
The first T. rex skeletons were actually mounted in this way,
and nobody questioned it for a long time.
But the discovery of new fossils and a renewal of interest in the 1970s
led to a so-called ‘dinosaur renaissance’,
which transformed how we see these ancient creatures.
Scientists reanalyzed the skeleton of T. rex, and saw that it was much more likely
to have a horizontal spine, with its back flat and its tail in the air.
After this, museum skeletons were remounted,
illustrations were updated in science books, and even popular films
like Jurassic Park showed T. rex as an agile, crouching hunter.
But studies have shown that many people still get it wrong.
Researchers think that it’s because there’s still so much kitschy stuff out there,
like cookie cutters and stuffed toys, that have the out-of-date upright posture.
Nevertheless, there’s been more than a hundred years of paleontology
since T. rex was discovered,
and new techniques have taught us a lot about what they’re really like.
For one, it looks like their tiny arms might not be totally useless.
Sure, T. rex does have comically tiny arms, and for a long time
scientists wondered how they could do much of anything.
But paleontologists speaking at a conference in 2018 presented
some evidence that they were more flexible and useful than previously thought.
The researchers used X-ray imagery and computer models to look at the joints
of some of T. rex’s modern relatives -- specifically, turkeys and alligators.
Their research hasn’t been published yet, but they propose that those tiny arms
could actually have brought prey in close for a bite.
However, while its arms may have been better than we imagined,
its legs are a bit of a letdown.
T. rex’s long, sturdy leg bones have been used in the past to argue
that they could run fast, like an ostrich.
But because the muscles and tendons that actually do the running
aren’t preserved in the fossil record, estimates haven’t been very precise.
You can’t just guess based on a smaller animal scaled up,
because big animals like T. rex put proportionally way more strain on their bones
and muscles, compared to smaller ones.
Using different methods, scientists have suggested top speeds
that range from eighteen to more than seventy kilometers per hour.
That’s a bit of a mixed bag.
A study in 2017 took a new approach, combining biomechanical simulations
with measurements of stress on the skeleton.
This revealed that if they even tried to run,
it would put too much force on their leg bones, causing them to fracture.
So T. rex was probably limited to a fast walk, or a birdy sort of jog.
Basically, it works out to a maximum speed of about thirty kilometers per hour.
That means an Olympic sprinter would easily be able to outrun one!
Though… not for very long.
Also it means I definitely couldn’t.
While new techniques are giving us insight about old fossils,
new fossils are turning up that change our thinking too.
Which brings us to the feather question.
In the last few decades, remarkably preserved fossils are revealing
that all kinds of dinosaurs had soft, downy feathers, including relatives of T. rex.
Dilong paradoxus, a small ancestor of T. rex,
was discovered to have simple proto-feathers in 2004.
And the nine-meter-long Yutyrannus, described in 2012,
is the largest feathered dinosaur discovered yet.
It was previously thought that only the smaller dinosaurs had feathers,
because small bodies tend to need more insulation than big ones.
But huge fluffy Yutyrannus made us think again.
Soon, the idea of feathered bodies expanded to include all tyrannosaurs,
including T. rex, because scientists think a trait like that
isn’t easily lost by evolution.
But a study in 2017 analysed brand new fossils of T. rex skin,
which were scaly, not feathered.
These two conflicting points of view have sparked intense debate among
paleontologists, intense enough that, like, we don’t want to get into it
But this is definitely a mystery we won’t be able to solve for sure
until we have more fossils.
We don’t know for sure, but it’s possible that baby T. rex
may have been born fluffy, with insulating feathers over their bodies.
Adults could have retained a few feathery bits here and there,
but the matter is far from settled.
In a way, though, that’s exciting.
It shows how much there still is to learn even about something we think we know well
like this familiar staple of every six-year-old’s toy chest.
Who knows what we’ll learn in the next hundred years?
In retrospect, it’s easy to poke fun at those old,
incorrect museum mounts of T. rex and other dinosaurs.
But science is a process of sifting through ideas
and discarding the ones that don’t hold up to experimentation.
These ideas, right and wrong, are celebrated in the song
The Idea from the album Music for Scientists.
The song also has an original music video that fuses original artwork
and machine learning -- just like the whole album ponders
the intersection of art and science.
If that sounds like it might be your jam,
you can start listening to Music for Scientists at the link in the description.
[♪ OUTRO]