Welcome back to the Deep Dive. Today we are,
we're not just talking about a dinosaur. We are
talking about, well, I think it's fair to say
we're talking about the dinosaur. Right. And
I really don't say that lightly. No, you're absolutely
right. It really is the, you know, the definitive
article, isn't it? It holds a special place.
It really does. I was thinking about this on
the way in. If you walk into any kindergarten
classroom, pretty much anywhere in the world,
and you ask a five -year -old to draw a dinosaur.
What are they going to draw? They're going to
draw one of two things. It's either going to
be a Tyrannosaurus Rex, you know, big teeth,
tiny little arms. Or this one, the one with the
three horns and the big shield on its head. Exactly.
We are talking about Triceratops. And I feel
like everyone listening right now has a very,
very specific image in their head. It's probably
a plastic toy you had when you were growing up.
Oh, for sure. Maybe it was from a certain. a
movie franchise set on an island it's that toy
box version of the animal which is a great starting
point i mean it's iconic for a reason but the
reality of this animal is It's just so much stranger,
so much more dynamic, and frankly, so much more
terrifying than that static little plastic toy.
That is exactly the mission today. We are going
to take that toy box version and, well, we're
going to upgrade it. We're going to look at the
sources. And we have a huge stack today from
the original 19th century descriptions to some
really cutting edge papers from the last couple
of years. And we're going to find out that this
animal was a marvel of social complexity, a biological
shapeshifter, and maybe. just maybe a little
bit bristly. And we absolutely have to talk about
cowboys. We absolutely have to talk about cowboys.
I tease that and I promise we will get to the
Wild West. Yeah. But before we get to the lassoes
and the ranchers, let's just ground ourselves
in the name. Yeah. Because it's one of the few
scientific names that the general public actually
knows and, you know. uses correctly. It is, yeah.
It's a linguistic masterpiece, really. It's derived
straight from ancient Greek. You have tri, which
means three. Right. You have kiras, which means
horn. Okay. And then you have emphomes, meaning
face. Triceratops. Literally. Three horned face.
It's so elegant, so descriptive. It's perfect.
It doesn't require a degree in Latin to get the
picture in your head. You hear the name and you
see the animal. It is perfect branding. But here's
the so what question to kick us off. Why does
this specific dinosaur matter so much? I mean,
aside from being incredibly cool looking on a
lunchbox. Well, scientifically, it is. It's foundational.
It's incredibly important. In phylogenetic taxonomy,
that's the science of how we classify organisms
based on their evolutionary relationships. Triceratops
is actually used as a reference point, as a pillar
to define what a dinosaur is. Wait, really? Say
more about that. It's the standard unit. Basically,
yes. The clade or the group that we call dinosauria,
it's technically defined as all descendants of
the most recent common ancestor of Triceratops
and modern birds. That is heavy. So it's not
just a random participant in the group. It's
one of the two pillars that holds up the entire
definition. Precisely. If you aren't related
to Triceratops or birds in that specific way,
by that definition, you aren't a dinosaur. So
in a very real technical sense, Triceratops anchors
the entire family tree. And beyond that, historically,
it's significant because of when it lived, right?
It's right at the very, very end. Exactly right.
It was one of the very last non -avian dinosaurs
standing. It lived at the end of the Maastrichtian
age for about 68 to 66 million years ago. So
it was there right up until the asteroid hit.
If you could go back in time and stand on the
ground on that final day, you know, just before
the impact and look up at the sky. The animal
standing next to you in that forest was very,
very likely a Triceratops. Talk about witnessing
the end of an era. It's the final boss of the
Cretaceous. In many ways, yes. It was the culmination
of 150 million years of dinosaur evolution. Okay,
so we know what it is. We know why it matters.
But I want to go back to when we didn't know
what it was. Because the discovery story of Triceratops
is, well, it's a comedy of errors. It's almost
unbelievable. It really is. And it highlights
something so important about paleontology. Even
the absolute... best experts, the giants of the
field, can get it completely wrong if they don't
have the whole picture. So let's set the scene.
It's 1887. We are deep in the American West.
The Bone Wars are raging. Oh, absolutely. This
is the peak of the rivalry between Ockneal Charles
Marsh and Edward Drinker Cope. They're sending
teams out all over the West, trying to one -up
each other, naming new species as fast as they
can dig them up. It's a frantic, competitive
time. And into this scene walks a geologist named
George Lyman Cannon. He's working near Denver,
Colorado. Right. And you have to picture Denver
in 1887. It's not the metropolis it is today.
This was a rugged country. Yeah. And Cannon is
out there doing his geology work, and he finds
a fossil. Not a whole skeleton, I'm guessing.
No, and that's the entire problem. It's just
a pair of large brow horns, the ones over the
eyes, and they're attached to a fragment of the
skull roof. It's just the very top of the head.
Okay. So he wraps them up, puts them in a crate.
And sends them off to the expert. He sends them
to Othniel Charles Marsh. And we have to contextualize
Marsh. This man was at Yale. He was one of the
titans of early American paleontology. He's the
guy who named Stegosaurus, Apatosaurus, Allosaurus.
If anyone in the world should know a dinosaur
when they see one, it's O .C. Marsh. So Marsh
gets this crate. He opens it up. He sees two
massive bone horns. What goes through his mind?
What's his process? Well, he looks at the horns,
for sure. But more importantly, he looks at the
notes on the geology. The person who sent it
noted the rock formation it came from. Marsh,
based on what he knew at the time, assumes that
Formotion is from the Pliocene epoch. And for
those of us who don't have the geologic timescale
tattooed on our arms, what does Pliocene mean
in this context? It means relatively recent,
geologically speaking. We're talking a few million
years ago. Crucially, this is long, long after
the dinosaurs went extinct. Ah. So right off
the bat, he's ruling out dinosaur. He thinks
he's looking at a mammal. Exactly. He thinks
these aren't dinosaur fossils at all. He concludes
they must belong to some kind of giant extinct
species of bison. Yes. He formally describes
it and names it bison alticornis, which means
the high horned bison. That is just fantastic.
So the very first triceratops fossils ever cataloged
were put in the books as a type of cow. A very
large, very strange cow. But, you know, to be
fair to Marsh, if you just saw those two brow
horns in isolation, which are made of bone and
probably looked a bit like the bony cores of
modern cattle horns, and you were told the rocks
they came from are only a few million years old,
a giant bison isn't an absurd conclusion. I guess
that's convergent evolution where different animals
evolve similar shapes. Precisely. But the universe
wasn't done messing with them yet. Because the
next big find, and this is my absolute favorite
part of the whole story, involves a literal cowboy.
This is the story of Edmund B. Wilson in 1888.
1888. So a year later, we're in Wyoming now,
and Edmund is a cowboy. He's not a scientist,
not a geologist. He's presumably out there on
horseback checking fences or looking for stray
cattle. And he's riding along a ravine, minding
his own business, and he sees something. He sees
a monstrous skull, as it was later described,
poking out of the side of the ravine. Now, you
have to try and imagine that. You're on a horse
miles from civilization. You've probably never
seen a dinosaur skeleton in a museum because
they barely existed yet. And a skull the size
of a small car is staring at you from out of
the dirt. It must have been, I mean, terrifying
or at least deeply confusing. What would you
even think that was? A dragon? Who knows? And
Edmund, being a practical man of the West, decides
he wants to retrieve it. Maybe he thinks it's
worth money. Maybe he just wants the world's
greatest trophy for the ranch house. But he doesn't
have a rock hammer. He doesn't have plaster jackets.
He has a rope. He has a lasso. This is the most
American scientific method I have ever heard
of. I'm going to lasso the science out of the
ground. It really is. The story goes that he
throws his lasso around one of the horns. He
ties the other end to the horn of his saddle
and he spurs his horse. He tries to yank this
massive fossil out of the cliff face by brute
force. And I'm guessing physics happens. Physics
happens. The fossilized horn, which is essentially
rock, snaps right off. Oh, that hurts my soul.
And to make it worse, the jolt of the horn breaking
off causes the rest of the massive skull to tumble
down into the cleft of the ravine. out of reach
but wilson he has the horn he takes that broken
piece rides back to the ranch and shows it to
his boss and his boss is the connection right
yes his boss is a rancher and an amateur fossil
collector named charles arthur guernsey and guernsey
thankfully knows who to call he shows the horn
to a man named john bell hatcher And we need
to put a pin in Hatcher. He's a major character
in this story. He is the fossil hunter's fossil
hunter. If Marsh is the academic general back
at Yale, Hatcher is the guy on the front lines,
the Indiana Jones of this whole operation. He
was unbelievably tough and had an incredible
eye for finding fossils. So Hatcher sees this
horn. And what does he think? Does he think bison?
No way. Hatcher sees this horn and he knows immediately
this isn't a mammal. He knows this is something
reptilian and something enormous. He gets Guernsey
to take him out to the ravine. He manages to
recover the skull. This very skull becomes the
holotype, the defining specimen, YPM 1820. And
he sends it to Marsh back at Yale. Okay. So now
Marsh has a complete monstrous skull. with a
beak, with giant brow horns. Surely now, he says,
okay, definitely not a bison. Well, partially.
He immediately realizes it's a reptile. He recognizes
it as belonging to a group he had named earlier
based on fragments, Ceratops. So he initially
calls it Ceratops horridus. But then, as his
team is cleaning the skull up, they find something
Marsh hadn't seen before, a third horn. The nose
horn. The nose horn in Triceratops. Oh, so that's
the final piece of the puzzle. Exactly. That
third horn on the nose convinces Marsh this is
a whole new genus distinct from Ceratops. He
renames it Triceratops' three -horned face. And
remarkably, to his credit, he publishes a correction.
He goes back and says, you know that giant bison,
Bisoneltichornis? That was actually one of these.
My mistake. That's good science. You have to
be willing to say, I was wrong. But once they
knew what to look for, the floodgates opened,
didn't they? This is where Hatcher really shines.
It was an absolute avalanche of fossils. Between
1889 and 1891, just the three -year period, John
Bell Hatcher went on an absolute tear in Wyoming.
He collected 31 more or less complete skulls.
31 skulls in three years. That is an insane level
of productivity. It's staggering physical labor.
You have to understand, these aren't chicken
bones. A triceratops skull with the surrounding
rock matrix can weigh thousands of pounds. Hatcher
and his team were digging these out. with pickaxes
and shovels, wrapping them in burlap and plaster,
loading them onto horse -drawn wagons, and dragging
them for miles across the Badlands to the nearest
railhead. And I've read that Hatcher basically
destroyed his health doing this work, right?
The physical toll was immense. He did. He worked
himself to the bone, often in brutal conditions.
But because he sent back this incredible wealth
of material, this library of skulls, March started
noticing differences between them. Differences
like what? Well, you know, no two skulls were
exactly alike. Some had slightly longer brow
horns that curved upwards more. Some had taller,
more fan -shaped frills. Some had a big, robust
nose horn. Some had virtually no nose horn at
all, just a little bump. And because this was
the 1800s, and the race was on to name as many
new species as possible. Marsh went naming crazy.
He was a classic splitter. If it looks slightly
different, he gave it a new species name. He
named Triceratops alatus, Triceratops flabilatus,
Triceratops calicornis, Triceratops serratus.
I think he named something like eight or nine
species in just a couple of years. And this really
sets the stage for a debate that, honestly, we
are still having today over a century later.
Are these all different species living side by
side? Or is it just one animal that changes shape
as it grows and ages? That is the central question
of triceratops science. But before we can even
get to the shape -shifting, we need to understand
the baseline. We need to build the beast. If
you are standing next to a fully grown triceratops
hortus, what are you looking at? You are looking
at a biological tank. A meat mountain. laughs
that that's an accurate description. The sources
consistently put them at 8 to 9 meters long.
That's 26 to 30 feet. And weighing anywhere from
6 to 10 metric tons, some estimates go even higher,
up to 12. To put that in perspective for everyone,
that's the size and weight of a very large African
bull elephant. But it's lower to the ground,
much bulkier, more powerfully built. And a huge
chunk of that size, a disproportionate amount,
is just the head. It has one of the largest skulls
of any land animal in history. The skull alone
can be 2 .5 meters long. That's over eight feet.
Eight feet for just the head. Just the head.
So think about a standard doorway in your house.
The entire skull wouldn't fit through it lengthwise.
It's longer than your doorway is tall. I can't
even process that. The head is almost a third
of the entire animal's length. How does that
not just tip over? How do you even lift that?
Massive, massive neck muscles and a very specific
skeletal structure to support it. The first few
vertebrae of the neck, the cervical vertebrae,
are actually fused together into a solid block
of bone called a syncervical. Ah, like a handle.
Exactly. It creates a rigid, powerful attachment
point for the enormous ligaments and muscles
needed to swing that head around. But let's look
at the business end of that skull, the mouth.
It's got that beak. It looked like a giant parrot
beak, but on a rhino. Yes, the rostral bone at
the front. It's narrow and very deep, which means
it was incredibly strong. This wasn't for delicate
nibbling. This was for grasping and plucking
huge bunches of vegetation. It would have been
covered in a sharp keratin sheath, and it could
probably snap through cycad trunks or thick branches
with ease. But inside the mouth, behind the beak,
it gets even weirder. They didn't have molars
for grinding like a cow, right? Not at all. They
had something far more complex and efficient.
We call them dental batteries. This is just fascinating
biological engineering. Okay, break that down
for me. What is a dental battery? Imagine on
each side of the jaw you have 36 to 40 columns
of teeth, all packed tightly together to form
one continuous cutting surface. Okay, a wall
of teeth. A wall of teeth. But in each of those
columns, there were three to five teeth stacked
vertically, one on top of the other inside the
jawbone. Stacked, like PEZ dispensers for teeth.
That is the perfect analogy. As the top tooth,
the one in use, wore down from chewing tough
plants, it would fall out and the next one in
the column would have already moved up to replace
it. It was a constant conveyor belt of new sharp
teeth. So how many teeth are we talking about
in total? At any given time, you could be looking
at a total of 432 to 800 teeth packed into that
mouth. That is a lot of teeth for an herbivore.
A huge number. And the way they worked was unique.
If you watch a cow chew, they grind their food
side to side. Triceratops didn't do that. Their
jaw mechanics meant that the teeth slid past
each other vertically in a high angle shear.
So they weren't grinding the plants to a pulp.
They were slicing and dicing them. Exactly. Like
a set of self -sharpening scissors or biological
garden shears. They were processing huge volumes
of fibrous plant material, palms, cycads, tough
ferns. These are not easy plants to eat. They
were like living wood shippers. Okay, moving
back from that incredible head, we have this
massive, robust body. And there was a huge debate
for a very long time about how they actually
stood, how they held up all that weight. The
four -limb debate. Yes, this is a classic in
paleontology. If you look at the old paintings,
the famous murals by Charles R. Knight from the
early 1900s, Triceratops is shown with its front
legs sprawled out wide to the sides, almost like
a lizard or a crocodile. Like it's in the middle
of a push -up, permanently. Right. And the logic
at the time was that the head was so absurdly
heavy, they needed that wide, stable base of
support to keep from toppling over. There's always
a but. But the biomechanics, the skeletal reconstruction,
and most importantly, the trackways, the fossilized
footprints they left behind, they all tell a
different story. The current consensus is that
they had an intermediate stance. What does that
mean, intermediate? It means the hind legs were
fully upright, columnar, right under the hips
like an elephant's. The front limbs were also
mostly upright, but the elbows were slightly
bowed out to the sides. It's not a full sprawl,
but it's not a perfectly straight pillar either.
So more like a modern rhinoceros than a lizard.
Much, much more like a rhino. They were active,
capable walkers. They weren't just lumbering,
sprawling beasts. But their hands were weird.
They retained a primitive condition. Primitive
how? Well, if you look at your own hand, you
can rotate your forearm so your palm faces down.
That's called pronation. Most quadrupeds do this.
Triceratops couldn't, or at least not fully.
Its hands were semi -supinated, so its fingers
pointed out away from the body. So as walking
with its hands turned out permanently, that seems
awkward. It does to us, but it clearly worked
for them. And it gets weirder. It only walked
on the first three fingers of each hand. Those
had hoof -like claws. Digits four and five, your
ring and pinky fingers, were vestigial. They
were just little nubs that didn't even touch
the ground and had no claws. It's amazing the
level of detail we can get from just the bones.
But recently, we've been getting incredible details
about the stuff that covered the bones. Let's
talk about skin. This is really exciting stuff.
For a hundred years, we just assumed leathery,
elephant -like skin. It was a default guess.
But in 2002, a specimen was found in Wyoming,
nicknamed the Lane specimen. And this one is
special. It has skin impressions. It does. It's
preserved via a very rare process called clay
templating. Basically, after the animal died,
bacteria formed a slimy mat over the dead body.
Clay then settled on top of that mat, creating
a perfect, high -fidelity mold of the skin texture
before everything rotted away. So what does it
look like? Is it just scaly? It has large hexagonal
scales, of course. That's the base texture. But
in the center of some of the larger scales, particularly
on the back and tail, there are these conical
projections, like little nipples or bumps rising
up out of the middle of the scale. And what does
that imply? Why is that significant? Well, in
modern animals, and especially in other dinosaurs
like Psittacosaurus, which is a very early distant
cousin of Triceratops, structures exactly like
that are known to be anchor points for quills
or bristles. So. A fluffy triceratops. A porcupine
dino? Maybe not fluffy like a kitten. Think more
like the sparse, thick bristles on a wild boar
or the quills on a porcupine. It completely challenges
that classic image of a purely scaly reptilian
tank. It might have been a spiky, bristly tank.
Which honestly somehow makes it even scarier.
It has a whole new texture to the animal that
we missed for over a century. It's a fantastic
reminder that there's always more to learn. Okay,
let's get to the main event. The part everyone
knows. The headgear. The three horns and the
giant frill. Why? What is the point? Why invest
so much biological energy in growing these massive
heavy bone structures? This is the million -dollar
question, and there isn't one simple answer.
We have three main theories that all probably
play a part. Let's start with Theory A, the one
we all learned as kids. Defense against predators.
The weapons theory. They evolved these horns
to fight off hungry predators like Tyrannosaurus
rex. And unlike some childhood myths, this one
actually holds a lot of water. We have hard,
direct evidence for this. The smoking gun. Or
the smoking tooth mark, I guess. There is a famous
Triceratops specimen that has a partially healed
bite mark on its brow horn. The spacing of the
punctures, the shape of the marks, they match
Tyrannosaurus teeth perfectly. So a T -Rex literally
bit this thing on the horn. bit it, and broke
it. But here is the crucial part of that story.
The bone shows signs of healing. There's callous
formation around the break. Which means the Triceratops
survived the encounter. Exactly. It fought a
T -Rex, took a bite to the face, and lived to
tell the tale. We also see healed puncture wounds
on the squamosal bone, that's the side part of
the frill, that also match predator bites. So
yes, they absolutely used these horns to defend
themselves, and they were effective. That is
just so satisfying to know. The epic battle of
the giants was a real thing. But what about Theory
B, the Civil War? Did they use these weapons
on each other? Intraspecific combat. Fighting
for mates, fighting for territory. For a long
time, this was just speculation. It made sense.
You know, modern horn animals do it. But then
came the specimen known as Big John. Big John.
Sounds like a wrestler. Might as well have been.
Big John is a massive Triceratops specimen, one
of the largest ever found. And he has a very
distinct keyhole -shaped hole in his frill. It's
a traumatic puncture wound. And when you analyze
the shape and size of that hole, it is a perfect
match for the tip of another Triceratops' brow
horn. So he got stabbed in the head by another
Triceratops. He did. And again, just like the
T -Rex bite, the bone around the hole shows signs
of healing. So this wasn't necessarily a fight
to the death, but it was violent. They were locking
horns and wrestling, and sometimes they missed
and stabbed each other in the face shield. Is
that a one -off, or is it common? It seems to
be pretty common. There was a statistical analysis
done that looked at a large sample of skulls.
They found that about 14 % of Triceratops skulls
have these kinds of traumatic injuries on the
frill and face. 14%. 1 in 7. That's a high injury
rate. That suggests this was a regular part of
their lives. It does. And what's really interesting
is when they did the same analysis on Centrosaurus,
another type of horned dinosaur with different
horn arrangements, they didn't find those kinds
of cranial injuries, which suggests Centrosaurus
may be fought by flank butting or body blows,
while Triceratops was specifically engaging in
head -to -head combat, locking horns. Like modern
deer or antelope do today. Exactly. But then
that brings us to Theory C. The display theory.
Maybe it's not all about violence. This is the
idea that the frill is basically a giant billboard.
Right. Think about that frill. It's a massive
surface area of bone. We know from grooves on
the surface that it was covered in a network
of blood vessels. So it could have been flush
with blood. It could have been flushed with the
blood to produce vibrant colors. Red, blue, complex
patterns. It was very likely used for sexual
selection males, showing off their big, colorful
frills to attract mates, or for species identification.
A way to say, hey, I'm a triceratops, you're
a triceratops, let's hang out. But there's a
complication with the sex appeal only theory,
right? And it has to do with the babies. A very
good catch. Yes. Studies of juvenile skulls,
some of them very small, show that the frill
and horns start developing very early in life,
long before the animal is sexually mature. If
the frill was only for attracting a mate, you
wouldn't expect a toddler triceratops to be investing
all that energy into growing one yet. So it's
probably a mix of all three. It's not one or
the other. Almost certainly. Evolution is thrifty.
If you have a giant, metabolically expensive
structure on your head, you're going to use it
for everything you possibly can. Species recognition,
defense against predators, wrestling with rivals,
showing off to mates, and maybe even thermoregulation
pumping blood into it to cool down on a hot day.
A Swiss Army knife of a face. A Swiss Army face.
I like that. Okay, speaking of faces changing
over time, we need to talk about the shape -shifting.
Because this is the part of the deep dive where
the science gets really, really trippy and controversial.
This is where we enter the modern era of triceratops
research, largely driven by the work of Jack
Horner, Mark Goodwin, and John Scanella. And
it starts with ontogeny. Ontogeny just means
growth, right? The study of how an animal changes
from a baby to an adult. Exactly. In 2006, Horner
and Goodwin published a landmark study. They
looked at a growth series of triceratops skulls
from tiny melon -sized baby skulls all the way
up to the mass of adults. And what they found
was that the animal undergoes a radical transformation
as it ages. It's not just getting bigger. The
whole head is changing shape. Completely. When
a triceratops is a baby, its little brow horns
are just short, straight nubs. As it grows into
a juvenile, the horns actually elongate and curve
backward over the frill. Backward. But every
toy, every movie has them pointing forward. That's
the adult form. As the animal hits adolescence,
something incredible happens. The horns stop
growing backward, the base of the horn remodels,
and they reorient themselves to start growing
forward and upward. That sounds painful. How
does that even work? It involves a lot of bone
resorption and redeposition. It's a very dynamic
process. And as they become adults, the horns
eventually hollow out at the base, probably to
save weight. But the biggest change, the one
that sparked the big controversy, is what happens
to the frill. And this leads us... Directly to
the biggest debate in recent dinosaur science,
the Taurosaurus debate. The Taurosaurus debate.
Okay, some context is needed here. Taurosaurus
was another dinosaur identified way back in 1891
by Marsh, right alongside Triceratops. It looks
very, very similar. Three horns, big frill, but
with two key differences. It has a much longer,
more elongated, almost rectangular frill, and
that frill has two large holes in it. Two big
windows called fenestri. Whereas Triceratops
is famous for having a relatively short, solid
frill. No holes. Correct. For over 100 years,
everyone agreed. Triceratops is one species.
Taurosaurus is another. They were cousin species,
maybe living in the same place at the same time,
but distinct animals. Until 2010. Until John
Scanella and Jack Horner published a paper with
a bombshell hypothesis. Taurosaurus does not
exist. Excuse me. What do you mean it doesn't
exist? We have the skulls. They argued that Taurosaurus
is not a separate species. It is simply a very,
very old, fully mature geriatric growth stage
of Triceratops. So Triceratops is the teenager
and the adult, and Corosaurus is the grandpa.
That is exactly their argument. Their hypothesis
is based on this idea of metaplastic bone. The
bone of the frill isn't like cement. It's living
tissue that can change throughout an animal's
life. They argue that as a triceratops gets really
old, past what we'd consider a prime adult, its
frill keeps lengthening and flaring out. To keep
it from getting ridiculously heavy, the bone
thins out in two specific spots, and eventually,
those spots resorb completely, opening up into
the holes we see in Torsorus. That is a wild
theory. What was the evidence they presented?
Well, their primary line of evidence was demographic.
They pointed out that we find lots and lots of
juvenile and sub -adult triceratops, but we have...
never, ever found a confirmed juvenile Taurosaurus.
That is suspicious. Very suspicious. It is. If
Taurosaurus is a real breeding species, where
are its babies? Where are the teenagers? All
the Taurosaurus specimens we have are huge, mature
animals. They also pointed to a few intermediate
specimens, skulls that look like they are halfway
between the two forms, with thinning bone where
the holes would eventually open. So case closed.
The textbooks need to be rewritten. Taurosaurus
is dead. Not so fast. This is science. We love
to argue. Other paleontologists, people like
Andrew Farke, Nicholas Longrich, Daniel Field,
they push back hard. What's their counter argument?
Where are the holes in the theory, so to speak?
They have several counterarguments. First, they
argue that some of the known Taurosaurus specimens
actually look skeletally mature in their bone
texture, suggesting they weren't fully grown
yet, which contradicts the geriatric stage idea.
And conversely, they've found some absolutely
massive Triceratops skulls that look extremely
old. The bones are fully fused and rubbed. All
the signs of old age are there. But they still
have the classic solid short frill. So if Triceratops
is supposed to turn into Taurosaurus when it
gets old, Why are there these really old triceratops
that haven't turned yet? Exactly. That's a major
sticking point. And finally, they argue that
the proposed mechanism, the bone growing, then
thinning, then opening holes, is an unprecedented
and incredibly complex transformation that we
don't see in any other known animal. So where
do we stand on this today? Is it 50 -50? It's
still a very active debate. The consensus has
not fully landed on one side. There was a more
recent study in 2022 by Mallon and others that
argued they have found sub -adult Taurosaurus
specimens, which, if true, would be strong evidence
that it's a real separate species. But the shapeshifter
idea, regardless of whether it's right in this
specific case, has fundamentally changed how
we look at all dinosaurs. How so? It's forced
us to accept that we can't just assume a different
shape means a different animal. It might just
be a different age. or even a different sex.
It makes you wonder how many other dinosaurs
in the museum are just distinct ages of each
other. Jack Horner has famously estimated that
up to a third of all named dinosaur species might
just be growth stages of other known dinosaurs.
We might be vastly, vastly overestimating dinosaur
diversity. That blows my mind. The implications
of that are huge. Okay. Okay, let's step away
from the bones for a minute and look at the world
they actually lived in. Part 5, Life in the Late
Cretaceous. We are in Laramidia. This was an
island continent. During the late Cretaceous,
a shallow sea called the Western Interior Seaway
split North America in two. Laramidia was the
western strip, what is now Montana, Wyoming,
the Dakotas, Alberta. And the environment itself,
what would it look and feel like? Humid. Subtropical.
You should be thinking of coastal floodplains,
swampy forests, meandering rivers. Think Louisiana
or the Florida Everglades, but the trees are
conifers, ferns, and early palms. And based on
the fossil record, if you were to take a walk
through that forest, you would essentially trip
over a triceratops. They were unbelievably abundant.
The paleontologist Robert Backer, who is another
famous and colorful figure in the field, estimated
that at the very, very end of the Cretaceous,
in the ecosystems preserved in the Hell Creek
Formation, Triceratops made up five -sixths of
the entire large dinosaur fauna. Five -sixths?
That's more than 80%. It's overwhelmingly dominant.
It's an ecosystem completely controlled by this
one mega herbivore. The famous fossil hunter
Barnum Brown once claimed he saw 500 Triceratops
skulls in the field in a single season. They
were the bison or the cows of the Cretaceous,
at least in terms of their sheer numbers. Were
they social like cows? Did they live in big herds?
That's the tricky question. The evidence is ambiguous.
We usually find their remains in isolation. A
single skull here, a partial skeleton there.
We don't have those massive bone beds of thousands
of Triceratops all dying together like we do
with some duck -billed dinosaurs. So they were
probably lungers. That was the traditional view.
Mostly solitary. But... There are a few tantalizing
exceptions. There is a fossil site in Montana
that has the remains of three juveniles preserved
together, maybe a little youth gang. And another
site in Wyoming has three individuals of varying
sizes, a large one, a medium one, and a small
one found together, perhaps a small family unit.
And there's that one specific pathology you mentioned
earlier. Oh, the stepped -on tail. Yes. There's
a triceratops vertebra from the tail that shows
a healed crush injury, the best explanation anyone
has come up with. Another triceratops accidentally
stepped on its tail. Which implies they were
walking close enough together to step on each
other's tails. Exactly. So the current thinking
is maybe they lived in small family groups or
had loose associations, but probably not those
thundering herds of thousands that you see in
movies. Now, you mentioned the environment was
warm and subtropical. Let's talk metabolism.
Yeah. Was Triceratops warm -blooded like a mammal
or cold -blooded like a lizard? The great metabolism
debate. This seesaws back and forth constantly
in paleontology. For a long time, the idea of
gigantothermy was popular. The idea that they
were so huge, they just stayed warm by retaining
heat. Like a giant living pizza stone, it takes
all day to cool down. A perfect analogy. But
a very recent study in 2022 by Jasmina Wayman
and her colleagues looked at the chemical signals
of metabolism preserved in the fossil bone, and
their results suggested that Triceratops might
have been... Ectothermic. Cold -blooded. A 10
-ton cold -blooded animal. Or at least having
a much lower metabolic rate, more similar to
modern reptiles than to birds or mammals, which
is really weird because all the evidence suggests
their earlier, smaller ancestors were warm -blooded.
So they might have evolved back to a slower metabolism.
That seems counterintuitive. It's possible. If
you're a giant animal living in a warm, stable
climate, generating too much of your own internal
heat can actually be a problem. You risk overheating.
So maybe for an animal this big, slowing down...
the internal furnace was actually a selective
advantage just lounging in the ferns soaking
up the sun and eating palms eating a lot of palms
and this leads to a really cool ecological detail
niche partitioning we know for a fact they lived
alongside another giant herbivore the duck -billed
dinosaur edmontosaurus right so you have two
massive plant eaters in the same forest how did
they not just eat all the same food and start
each other out Isotope studies of the enamel
in their teeth give us the answer. The different
chemical signatures show they were eating different
things from the same environment. Triceratops,
with its powerful beak and shearing teeth, was
eating tougher, lower -growing vegetation things
like ferns and cycads. And Montasaurus, with
its broader beak, was likely browsing on softer
plants or things that were slightly higher up.
They split the menu. Nature always finds a way
to pack more species in. It really does. So let's
bring this incredible deep dive in for landing.
We started with a bison mistake. We went through
the wild story of the cowboy and the lasso. We
built this biological tank with a parrot's beak
and garden shears for teeth. We covered the epic
battles with T -Rex, the brawls with each other,
and the mind -bending idea of a shape -shifting
skull. It's an amazing journey. From a few fragmentary
horns to a complex, living, breathing animal
that dominated its world. What's the single biggest
takeaway for you? When you think of Triceratops
now, what's the image that comes to mind? For
me, it's resilience. This was one of the last
ones standing. It evolved to be unbelievably
robust, to be adaptable. It survived predator
attacks that would kill almost anything else.
It survived brutal injuries from its own kind.
It so thoroughly dominated its landscape that
it made up the vast majority of all large animals.
It's the ultimate survivor. Right up until the
day, survival was no longer an option. And for
me, it's the mystery that's still left. The Taurosaurus
question is still unresolved. We're still debating
about the bristles. We're still piecing together
its social behavior. Even with hundreds of skulls,
we are still arguing about the fundamental nature
of what it actually was. And that's the beauty
of paleontology, isn't it? The past is never
a closed book. There's always another fossil,
another discovery that can change everything.
Here's my final provocative thought for you,
the listener, today. We talked early on about
how Triceratops is used to define the entire
group Dinosauria. It's one of the two anchors,
binding the mighty Triceratops to the modern
songbird. Yes, the two killers of Dinosauria.
But think about that shapeshifter concept again.
If Taurosaurus, an animal that looked different
enough to be named a separate species for 100
years, is just an old Triceratops, and if Jack
Horner is even partially right that maybe a third
of all dinosaur species are just different growth
stages, I want you to reconsider the next time
you walk through a museum. Look at the skeletons
lined up in the hall. How many of those are actually
unique species, and how many might just be the
teenager version of the skeleton standing right
next to the adult version? It makes you look
at the concept of biodiversity in a whole new
way. Are we looking at a prehistoric zoo filled
with hundreds of different species? Or are we
looking at a combination nursery, high school,
and retirement home for just a handful of very
changeable ones? A nursery and a retirement home.
I love that. On that note, thanks for diving
deep with us today. Keep asking questions and
keep looking at the bones. And please don't lasso
the fossils. Please do not lasso the fossils.
We'll see you next time.