Tyrannosaurus Rex.
King of the tyrant lizards.
It's 6 meters tall (20 feet),
12 meters (40 feet) long,
and it weighs upward of seven tons.
You can hide from it,
you might even be able to outrun it,
but do you really want to do this every day?
Roughly 66 million years ago,
a massive asteroid,
thought to be about 15 km (9 mi) wide,
hit the Earth with an impact equal to
several million nuclear bombs
detonating at once.
This triggered the sudden mass extinction
of approximately 75% of all
plant and animal species on the planet.
Among them was
the most powerful terrestrial predator
to have ever lived,
the Tyrannosaurus rex.
As one of the most popular prehistoric animals,
being able to see a T. rex in the flesh
is a pretty common fantasy.
But what if we got what we wished for,
and T. rex were still alive today?
Would humanity be able to
survive alongside them?
Were T. rex as vicious and as ruthless
as they appear to be in movies and TV?
Or would these massive dinosaurs
be more worried about us
than we'd be of them?
If T. rex were alive today,
chances are they'd be an endangered species.
Their terrifying reputation
would be no match for the
caused by humans.
Because of this,
T. rex populations would be a lot smaller,
and it's even possible that they
would have evolved to be a smaller size.
We'd probably have to keep them
in sanctuaries similar to a wildlife safari,
since letting them roam freely
would be bad for both T. rex and humans.
In the wild,
a T. rex would have to look out for
hunters or poachers
who'd want the thrill and the bragging rights
of taking down a seven ton beast.
But even if you were smart enough
to keep your distance,
a hungry T. rex looking for food
might find itself stumbling onto a farm,
or breaking into a city zoo.
And if you can't imagine
a rampaging T. Rex storming around your city,
just imagine an upright bus with two legs
and sharp teeth that have
a maximum bite force
of about 5,800 kg (12,800 lbs).
But it's not like T. rex
would always be out hunting humans.
Scientific evidence suggests that T. rex
might've been more like scavengers
than predators.
Unlike most predators
that tend to have super sharp vision,
a T. rex's eyes were small and weak.
This dinosaur also had unusually small arms
compared to rest of their body,
which wouldn't have been very effective
for fighting prey.
However, T. rex did have
unusually large olfactory lobes
as part of their brains,
which scientists think would have been helpful
for smelling rotting carcasses from far away.
But that same powerful sense of smell
might also draw T. rex to country ranches
or to urban meat factories,
which would almost certainly end in disaster.
A T. rex could eat up to
230 kg (500 lbs) of meat
in just one bite,
so your farm animals wouldn't last very long.
And if you wanted to defend them,
or simply prevent your house
from being crushed,
you wouldn't be able
to take on a T. rex without a gun.
And if you didn't have one,
you'd have to run for your life.
T. rex weren't super fast runners,
with some scientists believing
their top speed was around 16 km/h (10 mph),
so if you ran and hid in a dense forest,
where it would be hard for them to maneuver,
you might be safe.
You could also try to trip the T. rex
that's chasing you,
since they're top-heavy dinosaurs
that had a hard time getting up if they fell.
Of course, we wouldn't have to worry about
endangered livestock and outsmarting T. rex,
if we kept them safely confined
to wildlife preserves.
We could create large habitats for them,
and grow food to feed them,
so that their appetites
wouldn't get them or us into trouble.
The sanctuaries probably wouldn't
look like anything from Jurassic Park since,
well, we've seen how well that worked.
But maybe with enough space, food,
and under proper management,
humans could coexist with T. rex.
But the T. rex is just one type of dinosaur.
Could we live with others too?
What do you think the world would be like
if none of the dinosaurs ever went extinct?
That's a story for another WHAT IF.