If you were to ask a committee of say fantasy
illustrators to design a dragon but the catch
is they weren't allowed to talk to each other
and then you just sort of mashed all their drawings
together you might end up with something that
looks a little bit like Carnotaurus. Yeah that's
a pretty good analogy. It is a creature of just
absolute contradictions. Right. It just doesn't
seem like it should be real. It really is the
platypus of the Cretaceous theropods, you know.
You have these legitimate horns of a bull, a
face that looks like it ran into a wall. A clug
-smashed face. Yeah, exactly. And then you have
these legs that are, I mean, they look like they're
biologically engineered for Olympic sprinting.
Yeah. And then the arms. The arms make a T -Rex
look like a bodybuilder. A serious weightlifter.
And that's the thing. Usually when we see designs
like that in movies or games, we kind of roll
our eyes. We say, okay, that's a movie monster.
That's not a real animal. Right. It's over -designed.
But Carnotaurus is the reality. Yeah. It is,
and I don't think this is an exaggeration, arguably
the most specialized, derived, and frankly bizarre
predator to ever come out of the Southern Hemisphere.
It absolutely challenges our assumptions about
what an apex predator is even supposed to look
like. We are so, so conditioned by the Tyrannosaurus
model. You know, the big head, the massive bone
crushing bite, that sort of generalist heavy
duty build. And then you look at Carnotaurus,
which went down a completely different evolutionary
path. And it just it looks alien. But that's
exactly what we're going to do today. We're going
to try and move past the caricature. The villain
from the Disney movie. Yeah, the movie monster.
So we really dig into the biomechanics. We're
going to look at the fluid dynamics of its speed,
the structural engineering of that wild skull,
and maybe the ecological pressures that force
a dinosaur to evolve into, well, a meat -eating
bull. And the incredible thing is that we can
do that. We can base this deep dive on the holotype,
the original specimen. Because unlike so many
other dinosaurs where we're, you know, we're
pasting together a toe bone from here and a jaw
fragment from there. Right, a Frankenstein's
monster of fossils. Exactly. Carnotaurus gave
us almost everything in one single package. Including
the skin. Mm -hmm. Which... We have to talk about
the skin because that discovery back in 1984,
it didn't just tell us what this one animal looked
like. It feels like it fundamentally changed
the whole field of paleo art and our understanding
of theropod skin in general. It did. It was a
landmark find. It was really the first time we
could look at a large predator and say, with
certainty, this is the texture of a killer. Not
just scales, but this specific complex texture.
Okay, so let's set the stage. Where does this
story begin? It starts in 1984. The location
is the Chubut province in Argentina, Patagonia,
and the man in charge is the absolute legend,
Jose Bonaparte. Now, Bonaparte is a titan in
South American paleontology. I mean, he's the
one who really put the southern continents on
the map, especially during a time when all the
money and attention was focused on North American
dig sites. Absolutely. He was leading this huge
project, the Jurassic and Cretaceous terrestrial
vertebrates of South America project. It was
a massive undertaking. And they were working
in a geological unit called the La Colonia Formation.
And for those who haven't been to Patagonia,
the La Colonia outcrops are, I mean, they're
beautiful. but they are geologically unforgiving.
That's a good way to put it. And that unforgiving
nature is actually a key detail here. The preservation
of this specific animal was dictated by the rock
it was buried in. We aren't talking about, you
know, soft mudstone or loose sand where bones
get crushed. Right. No, we are talking about
hematite concretions, iron, iron. The skeleton
was found encased in this massive iron -rich
rock. Hematite is an iron oxide. So when it forms
a compression around a fossil, it basically creates
a sarcophagus that is incredibly, incredibly
hard. It's much denser than the surrounding rock.
Which sounds like a double -edged sword, right?
I mean, on the one hand, that iron tomb protects
the fossil from being flattened from weathering.
It's perfect protection. But on the other hand...
Getting the bones out of that rock must be an
absolute preparation nightmare. Nightmare is
the right word. It took years and years of mechanical
preparation. You can't just chip away at hematite
with a little brush. You risk destroying the
bone. But that hardness, that perfect casing,
is exactly why we have the skin. The mineral
replacement was so fine and the casing was so
rigid that it preserved the three -dimensional
structure of the soft tissues before they could
decompose or get flattened by sediment. It's
a geological miracle, really. And this wasn't
the only major find from that expedition, was
it? They found it alongside Amargosaurus, right?
The sauropod with the crazy double row of necks
binds? Yes, it was a banner expedition for them.
They found both Amargosaurus and Carnotaurus
in the same general time frame. But Carnotaurus
was the showstopper because it wasn't just a
pile of bones. It was an articulated skeleton.
Found in the death pose. Correct. Lying on its
right side with the neck arched way, way back
over the torso. That epistatonic posture. Which
we see a lot in theropod fossils. What causes
that exactly? It's caused by the desiccation
and shrinking of the heavy neutral ligaments
that run along the spine after the animal dies.
As they dry out, they contract and they're so
strong they pull the head and neck back over
the body. But seeing it in Carnotaurus, seeing
that massive bulldog neck wrenched back, it's
just a very visceral, powerful connection to
the moment of its death. And because of that
hematite sarcophagus. The skeleton was incredibly
complete. We have the skull, the vertebrae, the
arms, the pelvis. What are we missing? We're
missing the lower legs, so the shins and feet
and the very tip of the tail. And that's just
due to weathering where that part of the concretion
was exposed at the surface for thousands of years.
But otherwise, this is basically an autopsy of
a specific individual. And we know it was an
adult. An adult, yes. We can tell because the
sutures in the brain case, the lines where the
skull bones meet, were fused together. In a juvenile,
those are still separate to allow for growth.
So this wasn't an animal going through a growth
spurt. This is the finished, final product of
its evolution. So Bonaparte gets this incredible
specimen, and he names it Carnotaurus sastre,
which means... Flesh bull. Carno for flesh, torus
for bull. And Sastry is in honor of Angel Sastry,
the owner of the ranch where the fossil was found.
A fitting tribute. And Fleshbulk just, I mean,
it captures the essence of it perfectly. It's
not just the horns. It's the whole vibe, the
bulk, the power. It's perfect. But let's circle
back to that skin because you mentioned it changed
everything. And it really did. Before this discovery,
a lot of... dinosaur skin reconstruction was,
you know, it was pretty speculative. Right. It
was based on these tiny postage stamp -sized
patches from other dinosaurs or just people inferring,
well, they're reptiles, so they must have scales.
Exactly. It was a lot of guesswork. But Carnotaurus
provided a roadmap. It provided a whole landscape.
A landscape. I like that. So we have impressions
from all over the body. All over. The neck, the
shoulder, the thorax, the tail. And the very
first thing it told us, loud and clear, is...
No feathers. Which is a really significant data
point. Because by this time, especially later,
we know that many cholerasaurs, that's the lineage
that leads to birds and includes tyrannosaurs,
were feathery. So Carnotaurus, which is an abelosaur,
a totally different branch of the theropod family
tree. Yeah. It went hard in the other direction.
Completely staley. But here's the cool part.
It's not just scales. It's the complexity of
the skin. The base layer, the background texture,
is made of these small, non -overlapping scales.
Non -overlapping. That's interesting. So not
like a snake or a fish where they overlap like
shingles on a roof? Exactly. These are polygonal
scales that fit together perfectly, like a mosaic
floor or, you know, cracked mud. They range from
about 5 to maybe 12 millimeters across. It creates
this... really tough but flexible hide. Okay,
so that's the base layer. That's the base. But
then, interrupting this field of small scales,
you have these large conical protuberances, the
feature scales. The bumps, the studs. This is
the part that always shows up in the artwork.
These are the studs. They're big, four to five
centimeters in diameter. And they're surrounded
by a little rosette of slightly larger basement
scales. Now, for decades, paleo artists drew
these bumps in these neat, orderly rows running
along the length of the body. I can picture it
now. It looks like it has racing stripes made
of osteoderms. Very tidy, very, you know, designed.
And it turns out it's very wrong. There was a
major study in 2021 by Christoph Hendricks and
Phil Bell. They reexamined the skin impressions
using modern imaging techniques, and they found
that the distribution of these feature scales
is actually... Random. Random. So no rows at
all. No neat rows. It's a chaotic, irregular
distribution, which when you think about it,
looks much more organic. That does make more
sense. Nature rarely does perfect geometric rows
unless there's a very specific reason, like,
you know, segmentation in an insect or something.
Exactly. And they also found that the little
basement scales, the small ones, they change
shape depending on where they are on the body.
On the chest, they might be sort of conical.
Elsewhere, they're more lens shaped or polygonal.
It shows a really high degree of regionalization
in the skin. So what's the function of the bumps?
I mean, what's the why? Is it just armor? Protection
is definitely the leading hypothesis. The best
modern analogs we have are things like the green
iguana or the marine iguana. They have these
large, bumpy, tubercular scales often on their
neck and back. And they use them for fighting.
They do. They serve to protect against bites
and scratches during what we call intraspecific
combat. So fighting with other members of their
own species. And we are going to get to the combat
later, but given the horns on this thing, it's
a safe bet these animals were getting up close
and personal with each other. That's the idea.
There's also a secondary hypothesis about thermoregulation.
Heat regulation. Yeah. A large, active animal
living in the Cretaceous, which is a greenhouse
world much warmer than today, needs to be able
to dump heat efficiently, especially an active
hunter. The varied surface area between the flat
scales and the projecting bumps might have created
microturbulence in the air flowing over the skin,
helping to shed heat. Almost like cooling fins
on an engine. In a way, yeah. But the skin story
gets even wilder when you look at the face. Right.
The texture of the facial bones, the maxilla,
the nasal, the jugule is incredibly rough and
hummocky. It's not smooth. And in paleontology,
that rough bone texture usually implies a specific
kind of covering, right? It's not just skin.
It implies a cornified pad, a thick, horny keratinous
layer. Think of the texture on a rhino's face
near its horn or the beak of a turtle but spread
all over the snout. Wow. Carnotaurus likely had
a face that was covered in tough, horny armor.
It wasn't soft skin. Its face was a helmet. A
helmet with horns on it. That transitions us
perfectly to the skull itself. The demon's head.
Because if you look at a Carnotaurus skull in
profile, and then you look at, say, a Giganotosaurus
or a T -Rex, the difference is just jarring.
Carnotaurus looks squashed. Pug -nosed is the
common descriptor you hear, but I think bulldog
is probably more accurate, just given the ferocity
it implies. The skull is incredibly short for
its height. It's only about 60 centimeters long,
but it is very, very deep vertically. It gives
it a very distinct box -like head shape. It does.
And the snout isn't long and tapered like most
other big varipods. It's moderately broad. But
the features that really jump out at you, besides
the horns, are the orbits, the eye sockets. They're
weird shaped. They're keyhole shaped. And the
upper margin of the eye socket projects outward,
like a bony eyebrow, which would have protected
the eye from above. And the eyes themselves,
they're not facing out to the sides, are they?
They're not. They are rotated forward. There
is a definite overlap in the visual fields. This
implies binocular vision. So, stereoscopic sight.
Depth perception. Exactly. Now, it's not to the
extreme degree of a T -Rex, which had truly phenomenal
eagle -like depth perception, but it was certainly
enough to judge distance accurately, which...
You know, if you are a predator that moves at
high speeds, that's a non -negotiable requirement.
You do not want to run into a tree at 30 miles
an hour. Or miss the prey you're trying to ambush.
Yeah. But okay, let's talk about the main event.
The horns. These aren't just little bumps in
the skin. These are actual extensions of the
frontal bones of the skull. So solid bone. Solid
bone cores, yeah. They're about 15 centimeters
long. And they project diagonally upward and
outward from right above the eyes. You have to
remember that's just the bone core. Right. In
life, it would have been covered in keratin.
A keratinous sheath, just like the horns of a
bull or a ram today. And that sheath would have
made them even longer, thicker, and almost certainly
sharper. There was a lot of debate about these
for a while, right? Were they just for display,
like a peacock's tail, or were they actual weapons?
But the structure seems pretty robust. They are
incredibly robust. They're flattened from top
to bottom, dorsiventrally, and their internal
cross -section suggests they were built to take
impact. This isn't a delicate, paper -thin crest
like you see on a Dilophosaurus. These are functional
structures. And that leads us straight into the
behavioral questions. Why have horns? I mean,
the neat -eating bull nickname isn't just...
aesthetic. It implies a behavior. It does. And
for Carnotaurus, we have three main theories
for how they might have used them in combat against
each other. Okay, what's theory A? Theory A is
the ram theory. Straight up, like, bighorn sheep.
Two Carnotaurus run at each other from a distance
and collet coquet, a massive head -on collision.
But does the skull mechanic support that? I mean,
that's a huge shockwave to send through your
skull. The brain is right there. And that's the
main criticism of the theory. While the neck
is incredibly strong and muscular, the cranial
roof, the top of the skull, isn't quite as thickened
or dome -like as, say, a Pachycephalosaur, those
dinosaurs that definitely had butters. So a high
-speed direct impact might have been a bit too
risky. Okay, so that brings us to Theory B. Theory
B is shoving. Think of it as a sumo match. Just
slow push. Exactly. They lock horns or maybe
press the flat tops of their heads together and
they just push. It becomes a pure test of strength,
leveraging that massive neck musculature we talked
about, but without the high impulse shock of
a full -on collision. More like a shoving match
between marine iguanas. Precisely. A way to establish
dominance without risking brain damage. And what's
Theory C? Theory C for me is the most compelling.
It's the giraffe method. Or you could call it
neck flanking. I've seen videos of giraffes fighting.
It's brutal. It is absolutely brutal. They fight
by swinging their long necks and slamming their
ossicones, their horns, into the side, the neck,
or the flanks of their opponent. And we know
Carnotaurus had a powerful muscular neck that
was capable of rapid lateral or sideways movement.
So it could swing its head like a club. Like
a warhammer with two spikes on it. A sideways
swipe with those horns could easily break ribs
or tear huge gashes in the skin. And that makes
so much sense in the context of the skin armor
we just discussed. If you're evolving these brutal
sideways horn attacks, you also co -evolve the
studded leather jacket to help you survive the
fight. Precisely. It's an evolutionary arms race
happening within the species itself. The offense
and defense evolving in lockstep. Wow. Okay,
so we've got the horns, the armor. Now we have
to address the bite. This is probably the most
contentious part of Carnotaurus anatomy in the
scientific literature. You have one group of
scientists saying it had this flexible, almost
snake -like jaw, and another group saying it
had a surprisingly crushing bite. it's a classic
case of biomechanical modeling versus morphological
interpretation it's a real puzzle so on one side
you have the kinetic jaw hypothesis this was
largely championed by researchers like mazetta
and his colleague kinetic meaning mobile yeah
they looked at the joints and contacts between
the different bones in the skull and importantly
in the lower jaw there's a joint halfway down
the lower jaw called the intramandibular joint
they argued that this joint and others made the
jaw flexible that the bones could move relative
to one another. Kinda like how a snake can unhinge
its jaw to swallow a huge egg. A bit less extreme
than that, but it's a similar principle. They
suggested this flexibility allowed Carnotaurus
to do a couple of things. One, absorb the shock
of struggling prey. Two, it might have allowed
the lower jaw to bow outward slightly to accommodate
and swallow smaller prey whole or in very large
chunks. But that paints a picture of Carnotaurus
as a hunter of small game. A giant 1 .5 ton dinosaur
running around eating lizards and tiny mammals.
Or small dinosaurs, yeah. But it does feel a
little underwhelming for an animal this size.
And biomechanically... A kinetic jaw is a structurally
weaker jaw. If you bite down on a large, struggling
herbivore with a loose, flexible jaw, you risk
dislocation or fracture. Which is where the second
cam comes in, the bite force modelers. Right.
This is work by people like Francois Therrien.
They use a technique called finite element analysis,
it's an engineering method, to model the stresses
on a digital skull of Carnotaurus. And their
results were completely different. What did they
find? They found that the bite force was actually
quite high, potentially double that of a modern
American alligator. They argued the skull was
actually built for stress absorption, not for
flexibility. And this aligns much better with
the hatchet theory that Robert Baker proposed
years ago, doesn't it? It fits perfectly. Baker
looked at the whole picture, the short, deep,
reinforced skull, and especially the neck. The
neck of Carnotaurus is enormous. The muscle attachment
sites are just huge. And Baker proposed that
the animal didn't rely on jaw muscle power alone
to kill? He's saying it's not about the squeeze.
It's not about the squeeze. Instead, it used
its entire head and neck as a weapon. The jaw
was like a serrated axe head. So it would open
its mouth wide. Open its mouth wide, probably
raise its head up high, and then bring the entire
head crashing down, slamming the upper teeth
into the prey using the power of those immense
neck muscles. Driving the teeth in like a pickaxe.
A dental pickaxe. Exactly. And then you pull
back, and the serrated teeth create a massive,
deep slashing wound. This hit -and -run slashing
tactic is also supported by the teeth themselves.
They're relatively slender and blade -like, perfect
for slicing meat, not for crushing bone like
the thick, robust teeth of a T -Rex. It's a completely
different killing style. It's a surgical strike.
You inflict a massive wound, you slash the prey,
let it bleed out, and just wait. And that strategy
fits perfectly with the rest of the anatomy we
haven't even gotten to yet. Specifically, it's
incredible speed. You don't want to grapple with
prey if you were built like Carnotaurus. You
want to ambush, slash, and retreat before it
can fight back. Okay, speaking of speed, we've
thrown around the term Olympic sprinter, but
let's actually look at the hardware. This dinosaur
is often cited as being one of, if not the fastest,
large theropod. The Ferrari of the Cretaceous
is the go -to analogy, and it's not far off.
We are talking about top speed estimates that
fall somewhere between 48 and 56 kilometers per
hour. That's about 30 to 35 miles per hour. For
an animal weighing over a ton, that is terrifying
velocity. It's incredible, and the question is
how? What allows a bipedal animal of that size
to move that fast? And the answer really comes
down to its tail. The tail. Okay, so the tail
isn't just a counterbalance. Not at all. In sauropods,
the tail is the engine room. It's the anchor
for a critically important muscle called the
caudofemoralis longus. Okay. Break that down
for us. Caudo femoralis. Caudo refers to the
tail, the caudal vertebrae, and femoralis refers
to the femur, the thigh bone. So it's a muscle
that connects the tail to the thigh. And this
is the muscle that retracts the leg. It pulls
it backwards. Precisely. It attaches to the tail
vertebrae, runs down the leg, and attaches to
a prominence on the femur. When that muscle contracts,
it pulls the leg back with immense force. That
is your power stroke when you're running. So
the bigger and more powerful the cata femoralis
muscle is, the more power you can put into each
and every stride. And Carnotaurus, I'm guessing,
has a supersized cata femoralis. It has a monstrous
one. And we know this because of a really unique
anatomical quirk in its tail bones. This was
a discovery by Scott Persons and Phil Curry.
They noticed that in most theropods, the caudal
ribs, the little ribs that stick out from the
sides of the tail vertebrae, they stick straight
out sideways, kind of like a T -shape. But in
Carnotaurus, these ribs are angled sharply upwards,
forming a V -shape instead of a T. A V -shape.
So instead of having a flat top to the tail,
you'd have a deep groove on top. No, it's the
opposite. The V creates a massive amount of space
on the sides of the vertebrae underneath the
upward angled ribs. By angling those ribs up,
you create this huge sub -rectangular channel
running along the sides of the tail vertebrae.
And that entire space was filled by the patofemoralis
muscle. Ah, I see. So the tail is effectively
thicker, just packed with more muscle. Way more
muscle. Based on their models, they estimated
the muscle mass was between 111 and 137 kilograms.
per leg. That is just an absurd amount of horsepower.
It's an incredible engine, but there's always
a catch. Engineering, especially biological engineering,
is always about trade -offs. If you build a car
for pure straight -line speed like a drag racer,
you can't really turn corners very well. And
that is the Carnotaurus problem. That is the
carnotaurus problem. To support that massive
muscle and handle the forces involved, the tail
vertebrae themselves have these very complex
interlocking joints that make the tail extremely
rigid. It was stiff. It wasn't a flexible whipping
tail like you see in other dinosaurs. No, it
can't use its tail like a rudder, whipping it
around to help it turn. No, not at all. And turning
at speed, making tight corners, requires rotational
inertia and flexibility. If your body is basically
a stiff, heavy rocket, you're going to have a
very, very wide turning radius. So Carnotaurus
was a straight -line specialist. A drag racer,
not a slalom skier. Perfect analogy. It could
run you down in a sprint across an open plain,
but if you were able to zigzag between trees,
it would have to slow down significantly to reorient
its entire body to follow you. It really solidifies
that ambush predator hypothesis then. It's not
a pursuit predator that's going to chase you
for miles. It sees you, it bursts out of the
tree line at incredible speed, hits you with
that hatchet bite, and then it's gone before
you even know what happened. That seems to be
the most likely strategy, yes. It's all about
that initial explosive burst of speed. Now, we
cannot do a deep dive on Carnotaurus without
discussing the arms. Because, you know, we all
mock T. rex for its small arms. But Carnotaurus
arms are, I mean, they are barely there. They
are vestigial in the truest sense of the word.
They're not just small. They're bizarrely proportioned
and structured. The forearm is only 25 % of the
length of the upper arm, the humerus. So it's
mostly just an upper arm with a tiny little stub
at the end? Pretty much. And it gets weirder.
The hand attaches directly to the forearm. There
are no wrist bones. Wait, no wrist at all? No
ossified carpal bones. The metacarpals, the hand
bones, articulate directly with the radius and
ulna. It's like having your hand glued directly
onto your forearm with no flexible joint in between.
That's wild. And what about the fingers? It had
four digits, which is already strange for a theropod,
but digit number four was just a little splint
of bone, a spur. And the other fingers, especially
the middle two, were fused together. They couldn't
move independently. And they almost certainly
lacked claws. So let me get this straight. You
have a tiny, immobile hand that can't grab, can't
slash, can't reach the mouth. And it's attached
to a stiff arm with no wrist. It's a nubbin.
It's basically a decorative nubbin. For a long,
long time, people tried to invent uses for them.
You know, maybe they're for display. Maybe they
help brace during mating. But a 2009 study analyzed
the position of the shoulder socket and the actual
range of motion. And the arms were locked in
this outward flaring position. They were basically
doing a permanent jazz hands pose out to the
side. They couldn't even reach forward, let alone
touch each other. And surely the neurological
evidence must seal the deal on them being useless.
It does. When you look at the vertebrae, the
neural canals, the holes for the nerves that
would have gone to the arm muscles are extremely
reduced. This tells us the animal had very poor
motor control and sensation in these limbs. They
were on their way out, evolutionarily speaking.
It's such a classic example of an energetic tradeoff.
Evolution doesn't like to maintain expensive
tissue that it doesn't need. Exactly. Why waste
calories and developmental resources on arms?
If you are putting all of your evolutionary points
into building a massive skull, a huge neck, and
a turbocharged tail, you have to save energy
somewhere. The arms were the budget cut. So here's
a thought. If the lineage had continued, say,
for another 10 or 20 million years, do you think
the arms would have disappeared entirely? I think
it's almost certain. We see this today in animals
like skinks and some snakes. The limbs get smaller
and smaller over generations until they just
vanish. Carnotaurus was just caught in the middle
of that deletion process when the asteroid hit.
Okay, so we've built the animal. We have this
hyper -specialized armored horned speed demon
with useless arms. Let's place it in its world,
the La Colonia Formation. What does this ecosystem
look like? So we are in the late Cretaceous,
specifically the Mastrichtian stage, which is
the very last stage of the age of dinosaurs.
We're talking around 69 to 66 million years ago.
This is the end of the line. And at this point,
South America is an island continent, right?
Gondwana has mostly broken up. Correct. So the
fauna here is isolated. It's evolved on its own.
There's no T. rex here, no Triceratops. This
is a completely different world. And the environment
itself? The environment of the Lachlonia formation.
is coastal. We're talking about estuaries, tidal
flats, lagoons, basically a coastal plain that's
facing the Atlantic Ocean, which was transgressing
or moving inland at the time. It was a wet, lush
environment, but there's evidence of seasonal
dry spells as well. So who are the neighbors?
Who is Carnotaurus living with and probably eating?
Well, in the water, you have plesiosaurs and
a lot of different kinds of turtles. On land,
you have some early mammals, tiny things like
Rigotherium. But the other big dinosaurs are
the key to understanding Carnotaurus's role.
So... The prey animals. The prey animals. The
main herbivore we know of from this formation
is a sauropod called Titanomachia. A titanosaur,
so a long neck. A titanosaur, yes, but a relatively
small one for a titanosaur. It was probably around
six tons. Now, that's still a big animal, but
for carnivores, that is the perfect prey size.
It's too big to swallow whole, obviously. But
it's just the right size for that hatchet strategy
to be effective. Exactly. You run in, you deliver
one or two of those massive slashing bites to
the flanks or the legs. You weaken it and you
just wait for it to drop from blood loss. It's
the perfect prey. Are there any other predators
in this environment? There are. We have other
ablosaurids, including the recently described
colican. But based on the fossils we have, Carnotaurus
seems to be the largest predator in this specific
niche. It was the apex. It's just fascinating
to me to compare the southern hemisphere to the
northern hemisphere at the end of the Cretaceous.
In the north, you have the Tyrannosaurs, which
are these massive, bone -crushing generalists.
And in the south, you have the Avosaurs, these
speedy, short -faced slicers. Why the completely
different approaches to being an apex predator?
It all comes down to biogeography and the prey
that was available when the supercontinent Pangaea
broke up and then Gondwana after it. The ancestors
of these different predator groups were separated.
They were isolated. And they evolved to deal
with their local food sources. Precisely. In
the south, the dominant large herbivores were
the titanosaurs. And as we discussed, you don't
necessarily need to crush massive bones to kill
a titanosaur. You just need to bleed it out.
In the north, tyrannosaurs were dealing with
heavily armored prey like hadrosaurs and especially
ceratopsians, the horned dinosaurs. That might
have required a different tactic, one based on
overwhelming bone shattering force. So it's a
case of convergent evolution for the role of
apex predator, but completely divergent solutions
to the problem of how to kill. That's a great
way to put it. And Carnotaurus really represents
the absolute pinnacle of the Abelisaurid line,
specifically a group within them called the Brachyrostra,
which means short snouts. It took the basic Abelisaur
blueprint fast, short -faced, and just pushed
every single slider to the maximum. The shortest
skull? The shortest skull, the longest and most
powerful legs, and by far the smallest arms.
It's the extreme athlete of the family. It is.
And that's why it's so incredibly important to
paleontology. It shows us just how plastic and
adaptable the dinosaur body plan really was.
There wasn't one single way to be a successful
giant predator. So as we start to wrap this up,
I want to go back to that idea you mentioned
at the start of the evolutionary experiment.
When you look at the whole picture of Carnotaurus,
what is the big overarching takeaway for you?
For me, it has to be the concept of hyperspecialization.
Carnotaurus wasn't trying to be good at everything.
It really, really wasn't. It sacrificed agility
for pure straight -line speed. It sacrificed
raw bite strength for bite speed and the shock
-absorbing properties of its skull. And it sacrificed
its arms for, well, for everything else. It went
all in on a very specific strategy. Very specific
lifestyle. It did. And, you know, usually in
evolutionary history, hyperspecialists are the
most vulnerable to extinction. They're fragile.
When the environment changes, they often can't
adapt because they're too locked into one way
of life. But Carnotaurus was thriving. It was
incredibly successful right up until the very
end, right up until the asteroid hit. Which,
it always makes you wonder, if the Chicxulub
impact hadn't happened, if that one asteroid
on that one day had just missed. That is the
ultimate what if in all of paleontology, isn't
it? It is. But specifically for this lineage,
where would it have gone? I mean, you mentioned
the arms would have likely disappeared completely.
What about the head? Could it have become even
shorter, even more specialized for that hatchet
bite? It's certainly possible. I mean, you follow
that trend to its logical conclusion. You might
have ended up with a dinosaur that was essentially
just a giant mouth on two legs with a massive
tail engine propelling it. The Pac -Man dinosaur.
The Pac -Man dinosaur, yes. A mouth with a turbo
engine attached to the back. That is a genuinely
terrifying image to leave our listeners with.
A two -ton Pac -Man sprinting at 35 miles per
hour through the ancient... Argentine jungle.
I think we're all very lucky we missed that particular
timeline. I have to agree. Carnotaurus is cool
enough as a fossil. I don't think I'd want to
meet the version that got to evolve for another
10 million years. Definitely not. Well, that
is the story of the meat -eating bull, a creature
of contradictions, of bizarre anatomy, and of
incredible specialized violence. Thank you for
joining us on this deep dive. Always a pleasure
to unpack the weird ones. And to our listeners,
keep exploring and we will see you on the next
deep dive.