(dinosaur growling)
(suspenseful music)
(explosions)
Dinosaurs embody the extreme
in just about every possible way, their size,
power, even the long-ago time in which they lived.
It's no wonder, the more we learn about them,
the more they continue to captivate us.
I think that most people have an inherent fascination
with animals and with the natural world,
and dinosaurs are animals and the natural world
on the grandest of scales.
I think it's imagining living on our earth
when earth was a completely different place filled
with fantastical beasts that really ignites the imagination.
They're like dragons or other mythological creatures
but they were real, and that's part of the appeal.
They were a real thing.
They are awe inspiring.
Just take T. rex.
T. rex is a killer whale-sized animal walking around
on these giant chicken legs.
You can't really compare anything alive
to a T. rex.
We know when the reign of the T. rex ended.
In the calamitous dinosaur extinction event
65 million years ago, the result
of a massive meteor crash in the Yucatan Peninsula.
But how did its rule begin?
Scientists have long sought to learn more
about the early lineage of the king
of the tyrant dinosaurs.
Where and when can find the roots of its family tree?
Now, new discoveries, as well as new analysis
of old finds are beginning to fill in the timeline.
Almost all we know about Tyrannosaur evolution comes
from the final 15 million year of the Cretaceous
leading up to the great T. rex.
There's been this huge gap, 70 million years
in the fossil record prior to that
where we've had no fossil evidence
of what types of Tyrannosaurs were living here,
so we really had not pieced together the first three
quarters of the story of tyrannosaur evolution
here in North America.
Lindsay Zanno is the head
of paleontology at the North Carolina Museum
of Natural History.
For more than 10 years now, she's led research teams
to a remote part of central Utah following a trail
of small ancient Tyrannosaur teeth on the hunt
for something more.
(laughing)
You guys, you're really helping.
It's exciting to be part of the discovery.
I think that's my favorite part of the scientific process
and when we're out in the field, we come across things
we never expected to find that can define our research
for years to come.
And that's just what happened in 2012.
All right, so this is the upper leg bone.
When they found the puzzle pieces
to a new species of dinosaur, something very different
than anything they'd seen before.
The knee would have been here, and this is the
lower leg bone.
You can see where cut a section out
to study those growth lines.
It was amazing.
The first part we saw sticking out of the hill
was this bone and these pieces here are different colors
because we actually found each one of these
individual pieces trailing down the hill,
collected them all, and then the preparation teams
spent hundreds of hours piecing together each one
of these little bits that we had collected
from the side of the hill.
After the painstaking excavation,
cleaning and assembly work, the team concluded
this leg belonged to a small, at most
about 180-pound animal, similar to older tyrannosaur fossils
found in Asia, hinting at a continental migration
to North America.
It's a very petite animal.
It would have been about human size.
So when this animal was standing next to you,
he probably would have been able to look you
right in the eyes.
And the tissue between is pretty consistent.
Zanno examined cross sections
of the fossilized bone to determine the specimen's age,
about seven at the time of death.
Just like counting the growth rings you'd find in a tree.
Its growth seemed to be slowing, so it was actually
approaching its adult body size when it died.
So this actually wasn't just a young Tyrannosaur
of a big species.
This was actually a tiny Tyrannosaur.
Seven years old when it died perhaps.
But a fossil that's now 96 million years old
and begins to fill in a 70-million year gap
in the fossil record of North American Tyrannosaurs.
Zanno published her findings in February, 2019.
I chose the name Moros intrepidus
just to represent that this is really the origin story
of the T. rex lineage here in North America.
Moros means the harbinger of doom, and T. rex
is definitely the doom bringer, so it all made sense.
On the dinosaur timeline, small Moros lands
in the mid Cretaceous period, while the enormous T. rex
lived during the late Cretaceous.
With 30 million years in between, what suggests
they're closely related?
An evolutionary adaption not present
in those early Asian relatives, a specialized foot.
One of the things that makes Tyrannosaurs so special
is they have a very unique foot.
It's very pinched and it's designed for running
and also being very agile.
So these were incredible hunters that were able
to chase down prey.
Moros is the earliest example of those special
tyrannosaur adaptations that we found
in the fossil record.
So somewhat like a T. rex is small, fast tyrant dinosaur
grown huge, not a big, fat tyrant dinosaur
that then was evolving a few new traits
to make it go a little faster.
Professor Thomas Holtz is a paleontologist
at the University of Maryland specializing in Tyrannosaurs.
He was part of the peer review for Zanno's paper.
And with that adaptation, when they got the chance,
Tyrannosaurs could become the fastest-moving
large predators of all time.
But they acquired it when they were still little guys,
and they were probably using that fast-running foot
as much to get away from being eaten
as to chase things to eat.
That's because during its time,
small Moros was not the apex predator.
(dinosaurs roaring)
This lush world belonged to the much larger Allosaurus.
Somehow though, the Allosaurus disappear,
perhaps victims of a changing environment
leaving Moros and its Tyrannosaur descendants
a void to fill.
And so likely as soon as their major competitors
were out of the scene, they were able
to seize that opportunity, increase in size really quickly
and take over as the top predators
of these new ecosystems.
But what drove the Tyrannosaur's
exponential growth remains a mystery.
From Moros weighing in at 180 pounds,
to the T. rex known as Scotty, now considered
the largest T. rex ever discovered, tipping the scales
at more than 19,500 pounds.
Why Tyrannosaurs evolved to to be so big is still
a huge paleontological question.
Tyrannosaurus rex pushes the boundaries
of any big carnivores that we know about.
Scott Persons investigates those boundaries.
A research fellow at the University of Alberta,
he's also lead author on a new study
about the dinosaur, Scotty, fossils found in the Badlands
of Saskatchewan in 1991.
But its skeletal assembly was only just installed
for display at the Royal Saskatchewan Museum in May, 2019.
Scotty earned its name because shortly after
it was discovered, the field crew got really, really excited
and they wanted that evening to raise a glass
to Tyrannosaurus rex, to toast the tyrant king.
And the only bottle that they had on hand
that seemed appropriate was a very old bottle of scotch.
I became involved in researching Scotty
only about two years ago.
That was after the fossils were fully excavated
and fully prepared, so they were ready for scientific study.
The team at the Royal Saskatchewan Museum
used laser scanners to create 3D images of the bones.
Now almost 30 years after the initial discovery,
Persons's new analysis revealed Scotty
to be the T. rex ever found, dethroning Sue
from the Chicago Field Museum.
We say Scotty is the biggest in terms
of its absolute body mass.
So those skeletal measurements that indicate
just how much the animal would have weighted
suggest that Scotty is the most massive.
And when you look at things like the girth
of the femur, so the femoral circumference,
when you look at the length of the lower jaw,
when you look at even the thickness of the shoulder,
Scotty comes out ahead.
Thomas Holtz also peer reviewed
Persons's paper.
And honest to goodness, we can't say that Scotty,
on the lean season, when there's not much food,
and Sue in the season when there's a lot of food,
Sue may have been heavier some times of the year,
and Scotty heavier some of the other times of the year.
But overall the evidence is, on average, Scotty
is a larger individual than Sue.
And Sue is already a really, really, really
massive individual.
So Scotty is the rex of rex's.
It's the king of the Tyrannosaurs.
An estimated 30 years old
at the time of death, Scotty is also the oldest
T. rex ever found.
In a world where Scotty and the other big animals
are around, are only living to about 30 years old,
it's telling us there's a lot of turnover going.
There's a lot of individuals changing over
in the population.
As I like to say, in the Mesozoic, life was cheap.
Scotty shows evidence of a busted
and then infected jaw.
Its got several broken and healed ribs.
Its also got a number of vertebrae in the tail
that shows signs of very strong compression
and that may be indicative of a place
where Scotty actually got bit by another Tyrannosaurus rex.
So Scotty's bones tell us a lot about its very long
and very violent life.
Nothing however is written in stone.
The chances that we've actually uncovered
the very biggest of all time Tyrannosaurs rex
is infinitesimally small.
So it's very unlikely that Scotty is going
to remain the king of the Tyrannosaurs forever.
Tyrannosaurus rex is an animal that was around
for millions of years.
It can be found from across western North America.
I find it impossible to believe that
in all that time and space, we have been lucky enough
to discover the single largest individual that ever was.
There are undoubtedly bigger Tyrannosaur skeletons out there
waiting to be found.
And maybe smaller ones too, descendants
of Moros Intrepidus that can continue
to fill in gaps in our knowledge.
We need to find more Tyrannosaurs that lived
slightly after Moros to really understand how quickly
they were able to grow and assume those
top predator roles here in North America.
In the span of a month, the world learned
new information about two fantastic creatures
that roamed the earth tens of millions of years ago.
What's next on the horizon?
How will the future shape the past?
More species of dinosaurs are being found now
than basically any other point in human history.
And so we right now are in the golden age
of dinosaur discoveries.
There are 50 to 70 new dinosaur species named
every single year.
It's incredible the pace of research
and also we're at a stage where we're able
to apply new techniques to the study of dinosaurs
that allow us to get new information from bones
that we've had in museum collections for a very long time.
We're filling in gaps in the history
of well-known dinosaurs and we're finding specimens
of even the most famous dinosaur that are telling us
new things about their biology, about their growth,
about their size, that we didn't know before.
We are no where at the end of learning about dinosaurs
and in generations to come, we will be knowing things
about the lives of these ancient creatures
that would probably blow our minds today.
(light music)