Okay, let's get into this. I want you to picture
a name. A name that sounds like, I don't know,
something a toddler made up to describe a monster.
Or maybe something from a cheesy B -movie. Exactly.
Jaganotosaurus. I mean, it literally translates
to giant southern lizard. It just sounds so on
the nose, a little fake. It does have a certain
lack of subtlety, doesn't it? Like a marketing
team came up with it. But for all the heavy -handedness
of the name, this was a very real... Very massive
animal. And that's the thing. For so long, the
public consciousness has been totally dominated
by just one king of the dinosaurs. Oh, absolutely.
Tyrannosaurus Rex. It's on the lunchboxes, the
bedsheets, all the movies. the undisputed heavyweight
champion of the world. Well, today we're going
to challenge that title a little bit. We are.
We're heading south, way down south to Patagonia,
Argentina. And we're going back in time specifically
to the late Cretaceous period, the early Cenomanian
age. So we're talking about a window of roughly,
say, 99 to 95 million years ago. And that's a
key distinction, isn't it? The world was a different
place. A very different place. This is Don Juana
we're talking about, the southern supercontinent.
The dinosaur evolution happening there was totally
separate from the North American story we all
grew up on. So that's our mission for this deep
dive. We're unpacking the story of Giganotosaurus.
We'll get into how it was found. And that involves
a dune buggy, which is my favorite part. It's
a great detail. And then the huge scientific
brawl over whether it was actually bigger than
T. rex. And the... the really surprising engineering
inside its skull because this thing was built
like a biological slicing machine. It truly was.
And what's so fascinating is that Giganotosaurus
represents a completely different. evolutionary
answer to the question, how do you become a giant
apex predator? Two different solutions to the
same problem. Exactly. Nature solved it one way
in the north and a very different way in the
south. Okay, let's start with that discovery
story because I love it when these huge scientific
moments happen in just the most random way. It's
1993. We're in the Badlands near a place called
Villa El Chocon in Patagonia. And there's this
guy, Ruben Dario Carolini. Now, usually when
you hear about these major finds, it's some tenured
professor leading a huge expedition. Right, with
a whole team of grad students and ground -penetrating
radar and all that. But Carolini, he's a mechanic,
an amateur fossil hunter, and he's just out for
a drive. In a dune buggy. In a dune buggy. You
have to love that image. He's just cruising through
the Badlands, and he spots a bone. Just, you
know, sticking out of the ground. A tibia. Right.
A lower leg bone. A tibia. And he knows it's
something big. But I really doubt he knew he'd
just stumbled on one of the most important paleontological
finds of the century. So he does the right thing.
He calls in the professionals. Yep. Specialists
from the National University come. He show up.
And what they uncovered was just remarkable,
not just for its size, but for how complete it
was. They found a specimen that was almost 70
percent complete. And we should pause on that.
I mean, 70 % might sound like a C - on a test,
but for a giant theropod, that is a lottery ticket,
an absolute grand prize. Why is it so rare to
find one so complete? Well, think about it. Apex
predators are rare in an ecosystem to begin with.
You have way more herbivores than carnivores.
Sure, like lions and zebras. Exactly. And then
for one to die in just the right spot to fossilize
perfectly? It almost never happens. Usually you
find a tooth, maybe a vertebra if you're lucky.
But here they had the spine, the girdles, the
femurs. A whole lower leg. Yeah. The skull was
a bit of a puzzle. It was scattered over about
10 square meters. But they had enough to piece
together a monster. And of course they had to
name it after the guy in the dune buggy. They
did. In 1995, paleontologists Rodolfo Correa
and Leonardo Salgado officially published their
description. Giga's for giant, Nodo's for southern,
Soro's for lizard. And the species name. Carolene.
In honor of Ruben Carolene. It's a great tribute.
And you can still see it today, right? The original
specimen. You can. It's the main exhibit at the
Ernesto Bachmann Paleontological Museum. And
they have it displayed on a sandy floor with
the original excavation tools right there with
it. It's a really cool touch. It really grounds
it. You know, it shows the human effort that
went into it. It does. But almost as soon as
that paper came out in 95, the comparison started.
And that brings us to the big controversy. The
heavyweight title fight. Giganotosaurus versus
T -Rex. The main event. So when Corey and Salgado
first described it, they didn't pull any punches.
They pointed straight at the femur, the thigh
bone. It was 1 .43 meters long. Which is about
5 centimeters longer than the femur of Sue. And
Sue is the biggest, most famous T -Rex specimen
we have. Exactly. So that 5 centimeters is just
2 inches. That was the first shot fired. So does
a slightly longer leg bone... automatically mean
it's a bigger dinosaur overall well that was
the initial thinking the first estimates put
giganotosaurus at about 12 .5 meters long so
41 feet and somewhere between six to eight tons
okay so that puts it squarely in the t -rex weight
class a real contender a contender for sure but
then Things got a little more complicated. Another
fossil entered the chat, so to speak. It did.
A partial jawbone, a dentary, that was actually
found earlier by a paleontologist named Jorge
Calvo. Found in 87, but they didn't know what
it was at first. Right. It wasn't assigned to
Giganotosaurus until 1998. Calvo and Coria looked
at it and realized it was identical to the original
specimen's jaw. Except for one thing. It was
bigger. It was 8 % larger. 8%. So they just did
the math and scaled up the whole animal? That
was the extrapolation, yeah. If you scale up
the entire skull based on that one jawbone, you
get a skull that is 1 .95 meters long. That's
over 6 feet. Just the head. Just the head. You
could practically stand up inside its mouth.
And that pushed the total body length estimate
up to 13 .2 meters. Suddenly, T -Rex is looking
over its shoulder. I can just imagine the T -Rex
fans were not happy about this. People get very
protective of their favorite dinosaur. Oh, not
at all. This sparked a decades -long scientific
back and forth. You had paleontologist Paul Serino,
for example, arguing that it's really hard to
judge true size from incomplete skeletons. Fair
enough. But then other estimates came out that
were even bigger. In 2007, yeah. Researchers
Therian and Henderson tried a different method.
They used skull length to estimate body weight.
And because Giganotosaurus has such a long skull,
their math came out with a weight of 13 .8 tons.
13 .8 tons. That's almost double the first estimate.
That's like two elephants. That's massive. But
that study had its critics. Because you have
to remember what family this animal belongs to.
The carcharodontosaurus. Exactly. And they naturally
have longer, somewhat lighter skulls compared
to the big, boxy, heavy head of a tyrannosaur.
So if you use skull length as your only metric
for weight. It might skew the results. It's like
judging a person's weight by how tall their hat
is. That's a little bit of a stretch. But yeah,
the proportions matter. You can't just apply
one formula to different families. So then someone
else came along and argued the other way. In
2013, Scott Hartman, who's famous for his incredibly
detailed skeletal drawings, he weighed in. He
argued that while Giganotosaurus might be longer,
T. rex was wider. Wider. You mean like barrel
-chested. Precisely. The torso width. Hartman's
take was that T. rex was built like a beer keg
on legs. Just thick, heavy, robust. While Giganotosaurus
was maybe a bit slimmer. More athletic, yeah.
He put Giga back down in that 6 .8 to 8 .2 ton
range. So T. rex is the linebacker and Giganotosaurus
is the NBA center. That's a great analogy. It
really depends on how you define bigger. Is it
length? Is it weight? Is it volume? And just
to muddy the waters even more, we now have Spinosaurus.
Ah, yes. Spinosaurus, the wild card. Generally
accepted as the longest theropod now, maybe over
15 meters. But it's a semi -aquatic fish eater,
a totally different kind of animal. So where
does the consensus land today? The consensus
is that Giganotosaurus is absolutely one of the
largest land carnivores ever. It likely rivaled
or slightly exceeded T. rex in length, even if
the mass estimates are still all over the place,
from 4 tons to nearly 14. Right. Regardless of
the exact number, if one of these walked past
your window, you would not be getting out a tape
measure. You'd be hiding in the basement. You
wouldn't be arguing about centimeters, that's
for sure. Okay, but let's move past just the
size. Because for me, the coolest part is the
hardware. You mentioned the skull shape. T -Rex
is famous for its bone -crushing bite. The bone
crusher, yes. Thick, almost banana -shaped teeth
designed to withstand incredible pressure. It
pulverizes bone to get to the marrow. Giganotosaurus
was engineered completely differently. It had
that low, long skull. Low and long, yeah. But
it wasn't built for crushing. It was built for
slicing. Slicing. If you look at the teeth, they
aren't round cones. They're compressed sideways,
serrated. They're like steak knives. A very large,
very messy surgical instrument. Exactly. The
whole design suggests it would slice through
flesh, cause massive soft tissue damage, not
pulverize the skeleton. And it had this very
peculiar feature on its lower jaw. A chin. A
chin, like a superhero chin. Sort of. The very
front of the lower jaw was flattened and had
this downward projecting process. We call it
a chin. The leading theory is that it is an adaptation
to resist tensile stress. Okay, break that down
for me. Tensile stress is what? Think about the
physics. If you bite into a huge animal with
the front of your jaws and then pull back to
slice, that tearing motion puts immense stress
on the tip of your jaw. It wants to pull it apart.
Exactly. That chin acts as a structural reinforcement.
It keeps the jaw from snapping under the tension
of that pole. It's brilliant engineering. That's
fascinating. And what about the rest of its face?
I read the nasal bones were rugose. Yeah, rugose
just means they were rough and wrinkly. And it
had this sort of ridge -like crest in front of
each eye. Not a horn like Allosaurus, but it
was prominent. What was that for? Display. Probably
display. In life, it might have supported some
kind of keratin structure. We don't know for
sure. But it would have given the animal this
very distinct, rugged look. It wasn't a smooth
-skinned lizard. Now, I have to ask about the
brain. We always hear that dinosaurs weren't
exactly rocket scientists. How does our giant
southern friend stack up? Not great. They've
done a latex endocast of the brain cavity. The
total brain volume was about 275 milliliters.
Which is that good? For an animal that size,
no. It gives it what's called an encephalization
quotient of about 1 .9. In plain English, it
had a much smaller brain relative to its body
size than a tyrannosaur did. So not the biggest
thinker. Not the biggest thinker. The olfactory
bulbs, the part for smell, were huge. So it was
an instinct -driven predator that could follow
a scent from miles away. But it wasn't solving
puzzles. Okay, so big body, knife teeth, reinforced
chin. Let's talk about the engine. Was it slow
and sluggish like a reptile or more active? That
connects to the whole warm blood debate. A study
back in 1999 looked at oxygen isotopes in the
bones. And they found it was homeothermic? Essentially,
yes. It maintained a stable internal body temperature.
Its metabolism was probably somewhere in between
a modern reptile and a mammal. Which is pretty
crucial, right? You don't get to be eight tons
by growing slowly. You don't. You need a higher
metabolism to fuel that kind of rapid growth.
So it grew fast. Could it move fast? Can I outrun
this thing in a Jeep? That is a subject of some
very intense debate. In 2001, researchers Blanco
and Mazzetta ran the numbers. They calculated
a theoretical top speed of around 14 meters per
second. Which is? About 50 kilometers per hour
or 31 miles per hour. That is terrifyingly fast.
That's faster than Usain Bolt for something the
size of a bus. It is. But, and this is a very
big but, they also pointed out the danger factor.
When you're that heavy. stability becomes a nightmare.
What do you mean the danger factor? Think about
an eight -ton bipedal animal tripping while running
30 miles per hour. The fall is fatal. Almost
certainly. The impact forces would be catastrophic.
Shattered ribs, punctured lungs, it's game over.
So while it might have had the muscle power,
it probably wasn't safe to do so. Some more recent
studies have walked that back. Yes. A 2017 study
suggested the skeletal loads on these giant theropods
might have limited them to walking gates only.
So no high -speed running. Just a very, very
fast, ground -shaking power walk. Which, honestly,
is almost scarier. This relentless stride that
you can't get away from. It's the inevitability
of it, exactly. So let's... Zoom out. We know
what it looked like, how it moved, what world
was it living in, who was on the menu. It was
part of that family, the Carcharodontosauridae.
Its relatives include Maposaurus, also from Argentina,
and Carcharodontosaurus from Africa. Which tells
us they were spread out before... After the Candelaris
Formation, it was the undisputed king. And it
wasn't hunting small game. It was sharing the
landscape with titanosaurs. Massive long -necked
sauropods like Andesaurus and Limasaurus. That
seems like a tough meal. How does one predator
take down an animal that might weigh five or
six times what it does? And that leads to one
of the most exciting theories about these animals,
the pack -hunting hypothesis. Right, the idea
that they work together like wolves. The evidence
for this comes mainly from its cousin, Mappasaurus.
Paleontologists found a bone bed with multiple
Mappasaurus individuals of different ages all
buried together. Which suggests they lived and
maybe died together. Rudolfo Correa suggested
it could point to group behavior. Because if
you want to hunt a 40 -ton sauropod, you can't
really do it alone. But if you have a gang...
You can take down a giant. Now, we have to be
careful. We don't have direct evidence of Giganotosaurus
doing this. We haven't found a gigi -gang. bone
bed but given the family ties and the prey it
was eating it's a very plausible idea and it
fits that jaw design we talked about if t -rex
is a crusher it grabs and holds on but if giga
is a slicer it suggests a war of attrition you
run in inflict a massive, deep wound with those
teeth, and then you retreat. You let the prey
weaken from blood loss. The pack would surround
it, keep it from escaping. And that's where the
jaw mechanics are so interesting. The jaw joint
was moved backward in the skull compared to other
theropods. What does that do? It allows for faster
jaw closure. It's built for speed. A quick snap
and slice, not the slow, immense pressure of
a tyrannosaur. You rush in, take a bite. back
off, let your pack mates distract it, and come
in again. It really is a completely different
strategy. It is. And that's the big takeaway.
Giganotosaurus isn't just T. rex, but from the
south. It's a parallel lineage. While Tyrannosaurs
were ruling the northern hemisphere with big
brains and crushing jaws. The cartarodontosaurids
were ruling the South with giant -sized slicing
teeth and maybe even social hunting. It really
does highlight how North America -centric our
view of dinosaurs can be. We think of Hell Creek,
T -Rex, Triceratops as the standard. But the
Southern Hemisphere was producing these titans
of equal, if not greater, It was a whole different
world down there. An arms race on a massive scale.
So we've unpacked the dune buggy discovery, the
size wars, the slicing jaws. It's clear Giganotosaurus
is an absolute A -lister. Without a doubt. An
evolutionary masterpiece. But I want to leave
our listeners with one final thought. We know
they never met. Giganotosaurus and T -Rex. Separated
by millions of years, thousands of miles of ocean.
But just as a thought experiment, you put them
in an arena. Ah, I know where this is going.
The ultimate showdown. You have... The brute
force crusher in one corner, T -Rex. And the
surgical slicer in the other, Giganotosaurus.
Who wins that fight? It's the classic debate,
isn't it? The tank versus the swordsman. The
T -Rex has the bite force. It's orders of magnitude
stronger. If it gets a clean hold, it can end
the fight in one chomp. Breaks the neck. Game
over. But Giga has the reach. And it's probably
longer. Maybe taller. It has the size advantage,
the reach, and those teeth. It doesn't need to
crush bone to inflict a fatal wound. If Euganodosaurus
can use its agility and reach to land a massive
slash to the neck or the leg first. The T -Rex
bleeds out. It's a real toss -up. It all comes
down to who lands that first clean hit. The knockout
puncher versus the one that inflicts death by
a thousand cuts. Well, one giant cut. One very,
very deep cut. A toss -up that I think I would
pay good money to see from a very, very safe
distance. A very safe distance. Maybe from orbit.
That's all for this deep dive into the Giant
of the South. It's just incredible to think that
this monster was stalking Gondwana. Thanks for
listening and keep asking questions. You never
know what you might find. Keep exploring.