Okay, close your eyes for a second. I want you
to picture the single most majestic dinosaur
you can think of. You're probably imagining that
one scene, you know, from 1993. The paleontologists
are just stunned that John Williams' score swells.
The Jeep stops. The Jeep stops, and there it
is. This towering, gentle giant rearing up to
get the highest leaves, and then it comes down
with this ground -shaking thud. It's probably
the most recognizable dinosaur silhouette. in
movie history, the Brachiosaurus. It was the
first fully computer -generated dinosaur most
of us ever saw. It's like the ambassador of the
Jurassic. It is. It's the pop culture icon. But,
and this is where I might have to ruin your childhood
just a little bit. Uh -oh. What if I told you
that the dinosaur you're picturing, the one in
the movie, the one in that famous Berlin museum,
the one on all the lunchboxes, isn't actually
Brachiosaurus? That is the big twist. Yeah. The
animal that everyone pictures is almost certainly
Giraffatitan, which is an African cousin. The
true Brachiosaurus, Brachiosaurus altithorax,
is this rare North American animal that honestly
looked pretty different. So it's a total imposter
situation. Yeah. We've been cheering for the
wrong dinosaur for, what, 30 years? Pretty much.
So today, on this deep dive, we're going to set
the record straight. We are going to find the
real... And in doing that, we're going to uncover
just this masterpiece of biological engineering.
I mean, we're talking about an animal that defied
gravity with its blood pressure, had a respiratory
system more like a bird's than a reptile's. Wow.
And grew from a tiny two meter long baby into
a 40 ton Titan. Let's unpack this whole case
of mistaken identity. But first, we have to go
back to where it all started, not on some island
off Costa Rica, but in the Colorado River Valley.
right around the turn of the 20th century. The
year is 1900. Paleontologist Elmer S. Riggs and
his crew, they're out from the Field Columbian
Museum, what we now call the Field Museum in
Chicago. And they're prospecting near Grand Junction,
Colorado. And the funny thing is, they weren't
even looking for dinosaurs. They were hoping
to find Eocene mammals, like prehistoric horses.
That is classic scientific serendipity. You go
out looking for a little horse, you find a monster.
Exactly. So Riggs' assistant, a guy named Harold
Minka, he's out walking and he stumbles on a
bone. But not just any bone. It's the upper arm
bone, the humerus, and it is just absurdly large.
How large are we talking? We're talking over
two meters long. That's about six and a half
feet. Just the upper arm bone. That's taller
than me. Taller than the average person. And
this leads to my favorite little story from the
original material. Riggs sees this bone and he's
totally baffled. He actually thinks it's a femur,
a thigh bone that's just been, you know, squashed
and deformed over time. Well, that's an understandable
mistake, right? I mean, for other big sauropods
like Diplodocus, the back legs were the huge
ones. They're the powerhouses. The front legs
are always shorter. Yeah. Those animals were
built like a... like suspension bridges, sloping
down towards the head, finding an arm bone that
was bigger than a thigh bone. It was unheard
of. It just broke all the rules of dinosaur architecture.
It completely broke the mold. Riggs eventually
figured it out, and he famously declared he'd
found the largest land animal ever. And that
weird proportion, that's what gives us the name,
Brachiosaurus. It comes from the Greek. Brachion
means arm, and soros means lizard. Arm lizard.
Arm lizard. Makes sense. And the specific name
Altothorax is from Latin and Greek, meaning deep
chest. Which also fits. If your front legs are
longer than your back legs, your whole body angles
up. You don't look like that suspension bridge
anymore. You look more like a giraffe. Precisely.
That deep chest and those long arms gave it this
steeply inclined trunk. It was a completely radical
body plan. But this is where the confusion starts.
Okay. Riggs finds this thing in 1900. It's huge,
but it's not complete. They only have about 20
% of the skeleton. So Chicago's got this fragmentary
giant. They know it's a big deal, but they don't
have the whole picture. But then, a few years
later, German expeditions head to Tanzania. Right,
to what was then German East Africa. And they
hit the absolute motherlode, the Tenduguru expedition.
And what do they find there? They find tons of
dinosaur material, including these nearly complete
skeletons that look remarkably similar to what
Riggs found in Colorado. A paleontologist named
Werner Janensch studies them and decides, OK,
these are close enough. And he names the African
species Brachiosaurus branchi. And because the
African skeletons were so complete, I mean, you
could build a whole thing in a museum. They become
the model for what a Brachiosaurus is. They became
the default, the poster child. The original specimen
in Chicago was kind of forgotten by the public
because it was just a few bones. But the one
in Berlin, that was a full standing skeleton.
So every movie, every toy, every poster was based
on the African one. For a century, yeah. But
even then, there were some whispers in the paleontological
community. Are these really the same animal?
And those whispers got a lot louder in 2009.
They became a shout. A researcher, Michael P.
Taylor, did his own deep dive, and he realized,
wait a minute, these aren't just different species,
they're different genera. How different are we
talking? He found 26 distinct anatomical differences,
which is a lot. In fact, they were more different
from each other than, say, Diplodocus and Beresaurus
are. So the African one got a new name, Giraffatitan.
Giraffatitan. I love that name. It's very fitting.
It is. So, okay, the star of Jurassic Park is
technically a Giraffatitan. So what makes our
original American Brachiosaurus Altothorax different?
If I put them side by side, what do I see? The
American Brachiosaurus is the heavy duty model.
Its trunk, its torso is about 25 to 30 percent
longer than Giraffitans. So it's just bulkier,
a longer body. Much bulkier, longer, deeper.
And the tail was probably 20, maybe 25 percent
longer and taller at the base. But the biggest
visual cue might be the stance. The stance. Yeah.
Brachiosaurus had arms that were slightly sprawled
at the shoulder. Sprawled? You mean like a bulldog?
A little bit, yeah. Not that extreme, but it
gave it this wider, more robust posture. It was
wider in the hips, wider in the shoulders. If
Giraffatian is a graceful giraffe, Brachiosaurus
is a tank. A very, very tall tank. And it's funny
you say that because in the place they found
it... The Morrison Formation out west Brachiosaurus
is actually incredibly rare. That's a huge point.
If you were walking around in the Jurassic, you'd
be tripping over a Camarasaurus or Diplodocus.
They're everywhere in the fossil record. Spotting
a Brachiosaurus would have been a really special
event. So we have this rare, massive, deep -chested,
slightly sprawling American giant. Let's talk
numbers. How big are we really talking? The estimates
do vary a bit, and that's mainly because the
original specimen Riggs found probably wasn't
even fully grown. It was a sub -adult. It was
still growing. Yeah. But based on what we have,
we're looking at an animal about 18 to 22 meters
long, so up to 72 feet. And the weight? That's
all over the place. The low end is around 28
tons. The high end is close to 47 tons. So let's
say a safe bet is somewhere in the 40 to 50 ton
range. Okay, that's just mind -boggling. Yeah.
And that's what gets me. You can't just scale
up a lizard to that size and expect it to work.
Gravity becomes this huge enemy. The square cube
law. Right. Your volume and your weight increase
way faster than your bone strength. So how did
it not just collapse into a pile of goo? The
answer is air. Lots and lots of air. And we're
not just talking about big lungs here. No, not
at all. We're talking about a respiratory system
that was incredibly similar to modern birds.
They had this whole system of air sacs in the
abdomen, in the chest, even running up the neck.
And these didn't just help it breathe. They actually
invaded the bones. What do you mean invaded the
bones? The vertebrae, the ribs. They were hollowed
out by these air sacs. The technical term is
pneumaticity. It's like building with carbon
fiber instead of solid steel. It drastically
cut down the weight of the skeleton without losing
strength. So if its bones were solid like ours,
it would have been too heavy to even move. It
might have been too heavy to lift its own neck.
Seriously. But this system did more than just
lighten the load. It also gave it a supercharged
engine. Hell so. Well, mammals like us, we breathe
in, we breathe out. It's called bidirectional
flow. You're always mixing fresh air with stale
air. But sauropods, like birds, had unidirectional
airflow. So the air only moves in one direction
through the lungs. Exactly. It's a continuous
loop. The air sacs act like bellows, constantly
pumping fresh air across the lung tissue, whether
the animal is inhaling or exhaling. It's incredibly
efficient at extracting oxygen, which you absolutely
need to fuel a body that big. To fuel a body
that big, you need a high metabolism. For a long
time, the thinking was that dinosaurs were cold
-blooded, slow -moving lizards. Yeah, that idea
is long gone. The consensus now is that Brachiosaurus
was homeothermic. It kept a stable internal temperature,
and endothermic, or warm -blooded, it had to
be to grow that fast and move that actively.
But wouldn't it have the opposite problem? A
40 -ton... warm -blooded animal must have generated
a crazy amount of internal heat. It would have
been like a biological furnace. And that's where
those air sacs come in again. They likely worked
as a cooling system, helping to radiate excess
heat away from the body's core. And some theories
suggest that big crest on its head also helped
cool blood going to the brain. Okay, let's go
there. The neck. You can't talk about brachiosaurus
without talking about that neck. In all the movies,
it's held high, almost vertical, like a swan.
But I remember a while back, scientists were
saying, no, they held their necks straight out,
horizontally. Ah, yes, the great neck posture
debate. That was a 1999 study that argued the
vertebrae weren't flexible enough to curve upwards
like that. They said it would have broken its
own back. It caused a huge stir, ruined a lot
of museum displays. I bet. Excuse me, sir, could
you please lower your multi -million dollar dinosaur
display? So where are we now? Is it up or is
it down? The pendulum has swung back, thankfully.
The current view is an inclined posture, maybe
60 to 70 degrees. So not a perfect vertical swan
neck, but definitely high. They were specialized
high browsers. So they were eating leaves about
30 feet up in the air. Exactly. It makes no sense
to have front legs that long if you're just going
to hold your head near the ground. Okay, phew.
But that brings us to a massive physics problem,
the heart. It's the ultimate plumbing challenge.
To get blood from your chest all the way up to
a brain that high, you're fighting an incredible
amount of gravitational pressure. A giraffe's
heart is already huge, and its blood pressure
is sky high compared to ours. And this animal
would need a heart that could generate maybe
double the blood pressure of a giraffe's. We're
talking about a heart that could have weighed
400 kilograms. That's almost 900 pounds. The
heart weighed as much as a piano. Just to keep
its brain from passing out. It was a cardiovascular
marvel every single second of its life. Okay,
so let's picture this animal day to day. The
old image was always the swamp thing, right?
Right. The 19th century idea was they were just
too heavy for a land. So they must have lived
in the water to support all that weight. You
see all those old paintings of them submerged
in a swamp with their heads sticking out. Which
is funny because Riggs, the guy who discovered
it, was calling that out back in 1904. He was
way ahead of his time. He pointed to the feet.
They're compact, like an elephant's foot, built
for solid ground, not splayed out for mud. He
pointed to the deep, narrow chest and those hollow
vertebrae. He knew it was a land animal from
day one. It just took science 50 years to catch
up with them. Pretty much. So it's walking on
land through these semi -arid fern savannas.
What's it eating up there? It's a highbrowser,
so it's going for conifers, ginkgos, tree ferns.
And its eating style was very efficient. It was
all nip and swallow. No chewing. Zero chewing.
Their teeth were like chisels just for stripping
vegetation off a branch. They'd just swallow
it all whole and let their enormous gut do all
the hard work of fermentation. It's basically
a walking fermentator. One that needed something
like 200 to 400 kilograms of plants every single
day. That is a lot of ferns. Now, the Jurassic
Park question. Could it rear up on its hind legs
like in the movie? Ah. Another great myth to
bust. While some sauropods, like Diplodocus,
might have been able to rear up, Brachiosaurus
was uniquely bad at it. Why? Remember that body
shape? Long front legs, deep chest. Its center
of mass was way too far forward. If it tried
to rear up, it would have been incredibly unstable
and would have probably just tipped over. Plus,
it was already 30 feet tall. It didn't need to.
It evolved the height so it wouldn't have to
do the gymnastics. Good point. Okay, let's talk
about its face. The skull of Brachiosaurus is
really distinctive. It has that huge crest right
on top of its head. A nasal bar, yeah. It creates
this big bony arch high up on the skull. And
for years people said, aha, that's a snorkel.
Which ties right back into the swamp myth. The
idea was its nostrils were on top of its head
so it could hide underwater. But we know now
that water pressure would have made it impossible
to inflate its lungs at that depth. But the hole
in the skull is on top. The bony opening is on
top, yes. But in 2001, a researcher named Lawrence
Whitmer did a great study. He looked at modern
animals and found that the fleshy nostril, the
part you actually breathe through, is almost
always at the front of that bony opening. So
even though the hole in the skull is high up,
the fleshy nostril tubes probably ran down its
face. Exactly. The nostrils you could actually
see were probably low on the snout near the mouth.
So what was the point of the big crest then?
if it's not a snorkel mount? That's the million
-dollar question. Maybe a heightened sense of
smell. Maybe it was a resonating chamber to make
deep, booming calls that could travel for miles.
Or, like you said, a radiator for the brain.
Or a radiator for the brain. It was probably
a combination of all those things. I love the
idea of them just rumbling to each other across
the plains. Now, before we finish, we have to
talk about the babies. Finding a baby sauropod
has to be incredibly rare. It's like finding
a needle in a continent -sized haystack. But
they did describe one, a juvenile specimen nicknamed
Tony. It was only about two meters long. So the
size of a pony. A pony, yeah. But a pony that
was shaped very differently from its parents.
This shows us they had allometric growth. They
changed shape as they got bigger. Like how a
human baby has a giant head. Exactly. Tony had
a much shorter neck compared to its body than
an adult did. Its arm bones were more robust.
And the bones hadn't become fully hollowed out
yet. That pneumaticity increased as they grew.
So they literally shapeshifted from this pony
-sized short -necked thing into a 40 -ton long
-necked hollow -boned giant. And they did it
incredibly fast. They probably hit sexual maturity
when they were only at about 40 % of their maximum
size. They were just built to grow at an explosive
rate. Okay, let's bring this all together. We
started with the movie Monster. We've ended up
with something that is, well, it's quite different.
It is. The real Brachiosaurus Altothorax was
a rare North American specialist. Not the slender,
vertical -necked animal from Africa. It was beefier,
deeper in the chest, with those slightly sprawled
front limbs. A warm -blooded, air -sack -filled,
land -walking biological machine that pumped
blood three stories into the air and ate half
a ton of food a day without chewing. And it really
shows us that getting the names right matters.
By separating it from Girafatetan, we get to
appreciate... I appreciate Brachiosaurus for
what it uniquely was. It really makes you wonder
if maybe the most famous dinosaur in cinema is
actually a case of mistaken identity, an imposter.
How many other prehistoric animals that we have
in our heads are just... That is the problem
with iconic images. They tend to stick even long
after the science has moved on. Well, next time
you're watching that 1993 classic, you could
be that person on the couch who pushes up their
glasses and says, actually, that's a Giraffatidon.
Just don't blame us if you don't get invited
back for movie night. Worth it for the accuracy.
Thanks for taking this deep dive with us. Keep
questioning the icons. And keep looking for the
real story that's in the bones. See you next
time.