I want you to close your eyes for a second. Imagine
you're standing in the middle of a floodplain.
It's hot, really hot. The air is thick, humid,
maybe smelling a bit like pine resin and rotting
ferns. You look around and there's no grass.
Just ferns, cycads, call conifers. A very alien
world. And in the distance you hear a sound.
It's not a roar exactly. It's a low frequency
rumble, something you feel in your chest more
than you hear with your ears. You've just stepped
out of the time machine about 155 million years
ago. Welcome to the late Jurassic. Right. And
if I'm standing there looking at the top of the
food chain, who am I looking at? Because if I
ask most people to name the scariest dinosaur,
they immediately shout. T -Rex. Of course. But
we are way too early for the Tarrant Lizard King.
Way too early. It's a great point. You are closer
in time to the T -Rex today than the T -Rex was
to the animal we're talking about. That fact
always blows my mind. Yeah. So the animal you
are looking at, the one making that rumble, is
the Allosaurus. The Lion of the Jurassic. Yeah.
That's the nickname. And it's earned. For millions
of years, this animal was the absolute ruler
of what is now North America. It was the most
abundant, the most successful large predator.
of its time. Abundant is the key word there,
right? It is. If you look at the Morrison Formation,
this massive stretch of sedimentary rock in the
western U .S., it is absolutely packed with Allosaurus
bones. They are everywhere. And that's what we
are unpacking today. Yeah. Because I think Allosaurus
gets a bad rap. It's often treated as the generic
meat eater. You know, the player two dinosaur.
The default theropod. Exactly. It's not as big
as T -Rex, not as weird as Spinosaurus. It's
just... Yeah. But reading through these sources,
I realized this animal is actually a biomechanical
masterpiece, a completely terrifying piece of
engineering. It really is. It's a completely
different engineering solution to the problem
of how to kill a giant animal compared to what
came later with the tyrannosaurs. So that's our
mission today. We're going to talk about that
engineering, specifically the hatchet attack
theory. which is one of the most violent concepts
I've ever come across in nature. It's brutal.
We're going to look at the Bone Wars, which is
the chaotic human drama behind its discovery.
And we're going to spend some time with Big Al.
Ah, Big Al. the most famous and perhaps the most
tragic Allosaurus we've ever found. His life
story is essentially a series of unfortunate
events written in calcium. It's just staggering.
It really is a window into what life was actually
like for these animals. But before we get to
the tragedy, let's start with the identity, the
name itself, Allosaurus. Different lizard. It
doesn't exactly strike fear into your heart,
does it? It really doesn't. Tyrannosaurus Rex
means tyrant lizard king. Velociraptor means
swift Caesar. And then we have different lizard.
Why did Othniel Charles Marsh, who named it in
1877, go with something so, uh... So vague. Well,
you have to look at it from his perspective in
the 19th century. He was just getting these bones
from his collectors out west and he was examining
the vertebrae, the backbone of this new find.
And he noticed something that at the time was
revolutionary. The vertebrae weren't solid blocks
of bone like, you know, crocodiles or lizards.
They were hourglass shaped inside with deep hollows
and cavities. Hollow bones. Exactly. Marsh looked
at them and thought, this is weird. This is different
from any reptile I've ever seen, hence Allosaurus.
It was a literal description of his first impression.
So it was an aha moment for him. A huge one.
But today we know exactly what those hollows
were for. It's a feature called pneumatization.
Pneumatization, like pneumatic tires? Air. Precisely.
These cavities held air sacs that were part of
the respiratory system. It's a system we see
in modern birds, their closest living relatives.
And what's the advantage of that? Two big ones.
First, it makes the skeleton incredibly lightweight
without sacrificing too much strength. You get
a bigger animal for less biological cost. Second,
it suggests a very efficient one -way respiratory
system. What do you mean one way? So when a mammal
like us breathes, we breathe in, the air goes
to our lungs, we extract oxygen, and we breathe
the same air back out. We're mixing old deoxygenated
air with new air. Birds and likely Allosaurus
had a system where air flowed in one continuous
loop through the lungs in these air sacs. It
means they had a constant supply of fresh, fully
oxygenated air. It's like having a turbocharger.
Which is high -performance machinery. Absolutely.
Built for an active lifestyle. But that leads
to the second part of its name, the species epithet,
Allosaurus fragilis. Fragilis. Fragile. You have
the top predator of the ecosystem, a two -ton
killer, and you name it fragile, was marsh trolling.
It does seem incredibly ironic, but it refers
specifically to those same weight -saving features
in the vertebrae. The bone walls of these hollows
were thin. Ah, so the different and the fragile
are pointing at the same thing. Exactly. Marsh
wasn't saying the animal is weak or delicate.
He was highlighting how elegantly and, yes, fragilly
constructed the spine was. It's the difference
between a tank and a fighter jet. A tank is just
heavy armor. A fighter jet is fragile in the
sense that it's light and highly tuned, but it's
still an incredibly dangerous weapon. I like
that analogy. So Allosaurus is the F -16 of the
Jurassic. Speed and maneuverability over brute
force. That's a great way to think about it.
Now, you mentioned Marsh, and you can't talk
about O .C. Marsh without talking about his nemesis.
Edward Drinker Cope. The Bone Wars. I feel like
we could do 10 deep dives just on these two guys.
They hated each other. Hate is a mild word for
it. This was a bitter, scorched earth rivalry
in the late 1800s. It was personal. It was professional.
It was nasty. It was all about ego, wasn't it?
Completely. They were racing to name new species,
to fill up the museums back east, to cement their
own legacies. And in their rush, they made a
complete mess of the science. How so? They were
getting crates of bones from Colorado, Wyoming,
Utah. often very fragmentary stuff. And every
time they found a toe or a tooth that looked
even slightly different, they slapped a new name
on it to claim priority. They were naming things
so fast they weren't even properly describing
them. So we ended up with this clutter of names
like creosaurus, labrosaurus, epentereus. And
dozens more. And most of those, after decades
of patient work by later paleontologists, turned
out to be just allosaurus. Different individuals,
maybe different ages or slightly different sizes,
but the same animal. The rush for glory just
created... confusion. It did, but it also led
to one of the most painful what -if stories in
the history of paleontology. It involves a specific
crate of fossils. The unopened box. The unopened
box. So Cope's team is out in Como Bluff, Wyoming,
a legendary site. In 1879, they excavate a massive
block of matrix containing a nearly complete
theropod dinosaur. A huge find. A career -making
find. They crate it up, ship it back to Cope
in Philadelphia, and he just ignores it. It sits
in his collection unopened. Why? Was he too busy
sabotaging Marsh, selling him mislabeled fossils?
Probably. That was a real tactic they both used.
He was so obsessed with volume, with finding
the next big thing, that he didn't properly analyze
what he already had. He just wanted to publish
a name and move on. He died in 1897. having never
opened that crate. So what happened to it? After
his death, his collection was sold to the American
Museum of Natural History. And in 1903, six years
after he died, they finally opened it. And inside
was specimen AMNH 5753. And that is? It is one
of the most spectacular, complete allosaurus
skeletons ever found. It's a cornerstone of our
understanding of the animal. Is that the one
in the famous painting? The green dinosaur crouching
over the Apatosaurus carcass? That's the one.
The iconic Charles R. Knight painting from 1907.
That image, which defined what a predatory dinosaur
looked like for generations of people, came from
the box Cope couldn't be bothered to open. Wow.
If he had just looked inside, he might have described
the definitive Allosaurus specimen and completely
stolen Marsh's thunder. It was right there in
his hands. That is just, it's paleontological
tragedy. It is. But the confusion didn't end
with Marsh and Cope. For a long time, the public
didn't even know the name Allosaurus. My grandfather,
for example, might have gone to a museum and
seen a label that said Antrodemus. What happened
there? That is a classic case of taxonomic bureaucracy.
It's all about the rule of priority. Meaning
whoever names it first wins. Exactly. Back in
1870, seven years before Marsh named Allosaurus,
a paleontologist named Joseph Lady, who was really
the grandfather of American paleontology, a much
more careful scientist than Marsh or Cope. Right.
Lady described a tail vertebra. Just half a tailbone,
really, that was sent to him from Colorado. He
named it Antrodemus. On the basis of one bone?
One partial bone. So... Decades later, in the
1920s, another paleontologist named Charles Gilmore
was studying the material. He looked at Leidy's
bone and said, hey, this looks identical to the
tail bones on Marsha's Allosaurus. Okay, so they're
the same animal. Right. And since Leidy named
his bone first, 1870 versus 1877, the strict
rules of taxonomy say the older name wins. Antrodemus
has priority. So because of one half -broken
tail bone, the name Allosaurus was thrown in
the trash. For about 50 years, yes, from the
1920s all the way to... the 1970s, scientific
papers and museum exhibits used the name Antrodemus.
It's a real shame. So what brought Allosaurus
back from the dead? A man named James Madsen,
he published this massive exhaustive monograph
on the fossils from the Cleveland Lloyd Quarry
in the 70s. And he successfully argued, look,
Antrodemus is based on garbage material. It's
a nomin dubium. A dubious name. Exactly. You
can't define an entire genus on half a tailbone
that could belong to anything. He made the case
that Allosaurus was based on much better, more
complete and more diagnostic material. And the
scientific community finally agreed. He resurrected
the name. Thank goodness. Allosaurus just sounds
better. It has a flow to it. It does. It rolls
off the tongue. Now, you mentioned the Cleveland
Lloyd Quarry, and we're going to get deep into
that later because it sounds like a prehistoric
crime scene. But first, let's establish where
this animal lived. We know it's an American icon,
Utah, Wyoming, Colorado, the Morrison Formation.
But I saw in the notes that there's a Portuguese
connection. Yes, this is fascinating. We have
confirmed Allosaurus remains from the Laurinium
Formation in Portugal. How does a dinosaur get
from Utah to Portugal? Do they swim the Atlantic?
No swimming involved. You have to remember your
paleogeography. In the late Jurassic, the Atlantic
Ocean was just a baby. It was a narrow seaway,
a rift that was just starting to open up. So
North America and Europe were still connected.
Much closer, certainly. There were likely land
bridges or shallow island chains connecting them,
especially during periods of lower sea level,
so animals could just... walk across. So it's
basically the same ecosystem on both sides. Remarkably
similar. It's almost a mirror image. In the U
.S., you have Allosaurus hunting prey like Stegosaurus
and Camptosaurus. In Portugal, you have Allosaurus
hunting, well, Merigaea, which is a type of Stegosaur,
and Draconix, a type of Camptosaur. It shows
that Allosaurus was a dominant transcontinental
success story. And it's the state fossil of Utah,
right? It is. Designated in 1988 purely because
of the sheer volume of bones found there, especially
at Cleveland Lloyd. Okay, let's get a good look
at this animal. Physically, if I'm standing next
to an adult Allosaurus fragilis, how small do
I feel? You feel very, very small. An average
adult is about 8 .5 meters long. That's 28 feet.
That's a decent -sized yacht or a large moving
truck. Good comparison. And the big ones, the
ones that live long enough to really bulk up,
could hit 9 .7 meters, maybe even 10 meters,
so 32 feet or more. And weight. The weight estimates
are all over the place, as they always are with
extinct animals. But a good ballpark is 1 .5
to 2 metric tons. So maybe 4 ,000 pounds? So
significantly smaller than a T -Rex, which is
like 7 to 9 tons. Oh, much lighter. A completely
different weight class. But again, remember the
fighter jet analogy. Allosaurus was built for
athleticism. It had a massive skull, a short
neck, and a long, stiff tail that acted as a
counterbalance. And unlike the Tyrannosaurus,
it had functional arms. It really did. to ask
about that. T -Rex gets endlessly mocked for
its tiny two -fingered arms, but Allosaurus was
packing some serious heat in the upper body department.
Oh, absolutely. The arms were robust, powerful,
and about 35 % of the length of the legs. That
is a very useful reach. And they ended in three
fingers, each one tipped with a massive recurved
claw. How big were the claws? The innermost claw,
the thumb essentially, was huge. It could be
over six inches long following the curve. They
were like meat hooks. What were they doing with
them? Were they slashing with them? Probably
not slashing so much as grappling. The range
of motion studies show they could reach forward
and pull inwards with a lot of force. Imagine
a linebacker grabbing you. Allosaurus could hook
onto the side of a prey animal, digging those
claws in to anchor itself, while the mouth did
the real work. That's a horrifying image. Being
hugged to death by three -inch hooks. It creates
a stable platform for the bite. Which is good,
because, speaking of the bite... Yeah. We need
to talk about the skull, because this is where
Allosaurus gets really, really weird. The horns
first. Let's start with the decorations. It has
those little horns over the eyes. The lacrimal
horns, yeah. They sit right above and in front
of the eye sockets. They give it that distinct,
angry eyebrow look. Were they weapons? Could
they headbutt with them? Unlikely. The bone itself
is a bit too thin and hollow for high -impact
smashing. If you headbutted another Allosaurus
or a Stegosaurus, you might break your own skull.
So what were they for? Sunshades. That's one
idea. Maybe they helped keep the sun out of its
eyes. But the leading theory is that they were
for display. Like antlers on a deer. Precisely.
In life, they would have been covered in a sheath
of keratin, the same stuff as your fingernails
or a bird's beak. That keratin sheath could have
been much larger, pointier, and almost certainly
brightly colored. So it could have had bright
red eyebrows to say, look at me, I'm healthy,
I'm dangerous. Or, I'm single and ready to mingle.
It's all about signaling fitness to mates and
rivals. Okay, so it had decent eyesight to see
those displays. Pretty good, yeah. It's binocular
vision. The area where the two eyes' fields of
view overlap to give you depth perception was
about 20 degrees wide. How does that compare?
It's less than modern crocodilians, but it's
definitely enough to judge distance for an attack.
It wasn't just relying on spell. Okay, but the
most important thing about the skull isn't the
decoration, it's the mechanics. You called it
cranial kinesis. Yes, cranial kinesis. It means
moving skull. And that's different from a T -Rex.
Completely different. A T -Rex skull is akinetic.
It's fused. It's a solid block of bone, like
a sledgehammer, designed to withstand massive
crushing forces. An Allosaurus skull is not.
Not at all. The joints between the different
bones of the skull were loose. They could flex
and move against each other. And the lower jaw
was even stranger. It had a hinge, a joint, right
in the middle that allowed it to bow outward.
Bow outward. Think of a snake swallowing an egg,
though not quite that extreme. As it opened its
mouth, the lower jaws could splay out to the
sides. Why would it do that? It dramatically
increased the gait. It allowed the throat to
widen and the animal to encompass a huge volume
of flesh. In fact, studies show Allosaurus could
open its jaws to an angle of 79 to 92 degrees.
92 degrees? That's wider than a right angle.
It's basically unhinging its face. It's a gaping
maw of teeth. That's terrifying. But here's the
thing that doesn't add up. Here's the paradox.
Lay it on me. You have this massive gape. You
have these scary serrated teeth. But when scientists
ran the numbers on bite force, how hard it could
actually clamp down, it came back shockingly
low. Yeah, shockingly weak for an animal its
size. How about low are we talking? Well, the
estimates vary, but the highest are around 8
,700 newtons. The lowest are around 800. For
comparison, a modern lion is about 4 ,000. A
saltwater crocodile is over 16 ,000. And a T
-Rex. A T -Rex is way up in the 30 ,000 to 50
,000 newton range. It's not even in the same
league. So wait, let me get this straight. It's
the top predator. It hunts giant long -necked
dinosaurs. But it has the bite force of a large
dog. That doesn't make any sense. It seems like
a massive contradiction, doesn't it? If I'm an
allosaurus and I bite a stegosaurus and I can't
crush bone, isn't the stegosaurus going to shake
me off and laugh? That's exactly what paleontologists
asked for decades. How does this thing kill?
And that question, that paradox, led to the hatchet
attack theory. This is the Robert Baker theory,
right? He's always coming up with these wild
ideas. Yes, and it was later refined and tested
by Emily Rayfield using a technique called finite
element analysis. What's that? It's basically
engineering software used to test stress on bridges
or airplane wings. You build a digital model
of the skull and apply forces to it to see where
it's strong and where it's weak. And what did
she find? She found that while the jaw muscles
were relatively weak for biting, the skull itself
was incredibly strong. But only in one specific
direction. Vertical impact. Vertical impact,
meaning top down, like a hammer striking a nail.
Exactly. The skull could withstand over 55 ,000
newtons of force, that's six times its own bite
force, if that force came from the teeth slamming
straight down into something. Okay, I think I
see where this is going. So the theory goes like
this. Allosaurus doesn't bite you like a dog
or a lion. It doesn't clamp and hold. It's not
a grappler. It's a slasher. It opens its mouth
to that insane 92 degree angle. It rears its...
its head high using its powerful neck muscles
and then it swings its head down like a medieval
battle axe. So it's face slamming the prey. It
is driving the upper jaw, the maxilla, into the
flesh. And you have to remember the teeth. The
teeth of Allosaurus are serrated and recurved,
but they're also laterally compressed. They're
like steak knives. They aren't round spikes for
crushing. They're flat blades for slicing. Precisely.
So it slams the teeth in, anchors them, and then
uses those powerful neck muscles to pull back,
ripping out a massive chunk of meat. That sounds
incredibly violent. But I have a physics question.
If I slam my open mouth into a solid wall of
muscle, am I not going to get a concussion or
just break my jaw? That's where the cranial kinesis
comes back in. The flexibility isn't a bug. It's
a feature. When the skull hits the prey, all
those loose joints flex slightly. The whole structure
gives a little. It acts like a shock absorber,
dissipating the energy of the impact across the
whole skull so the bone doesn't shatter. It's
a crumple zone for your face. Exactly. It's a
beautifully engineered system for high speed,
high impact slashing. You don't need a strong
bite. It's a slash and bleed strategy. You don't
crush the windpipe. You open a massive wound
and let the prey go into shock or bleed out from
a safe distance. It's surgical. Well, messy surgical.
It's ruthlessly efficient. But it opens up a
really, really disturbing possibility that some
paleontologists have raised. And that's a strategy
we might call flesh grazing. I hate the sound
of that already. And you should. Think about
the ecosystem. You have these giant sauropods
wandering around, Diplodocus, Brachiosaurus,
Apatosaurus. These things weigh 30, 50, maybe
even 80 tons. They're walking mountains. Right.
Even for a group of Allosaurus, trying to kill
a healthy adult is incredibly hard work and very,
very dangerous. You could get stepped on. You
could get hit by a tank. It's a huge risk. So,
what if you don't kill it? You just snack on
it. You're a two -ton predator. You're hungry.
You see a 50 -ton sauropod. You run up, use the
hatchet attack to rip off a 50 -pound chunk of
flesh from its flank or its tail. Then you just
leave. And the sauropod is so big it just...
It survives. The wound is serious, but not fatal.
It scabs over, it heals. You come back three
months later and do it again. So you're treating
the prey like a renewable resource, like a parasitic
relationship on a gigantic scale. Exactly. It
changes the dynamic from predator versus prey
to something more like host versus parasite.
Imagine living your life as a sauropod, knowing
that at any moment a lion of the Jurassic might
come screaming out of the ferns, rip a piece
of you off, and then just leave you to bleed.
That is pure psychological horror. It's worse
than being eaten alive. It's being eaten alive
in installments. That is going to stick with
me. It's speculation, of course, but the anatomy
allows for it. Is everyone on board with the
hatchet theory, though? Not entirely. There are
alternative theories. Some researchers point
out that there are no modern animals that hunt
this way, which makes it hard to test. They suggest
the strong neck was for resisting the pull of
struggling prey. The big cat clam. Sort of, yeah.
The idea is that they'd use those strong forelimbs
to grapple the prey, hold it steady, and then
use the jaws for a more conventional muscle -driven
bite to the throat or soft underbelly. The wide
gape isn't for a hatchet swing. It's just to
get their mouth around a bigger chunk of animal.
So the debate is still active. Very active. But
the hatchet model does a great job of explaining
the paradox of the weak bite and the strong skull.
And we do know for a fact that they got into
fights where the prey definitely fought back.
Yeah. We have to talk about the Stegosaurus evidence.
Yes. The ultimate Jurassic showdown. We have
direct fossil evidence of their conflicts. It's
like a prehistoric crime scene. Exhibit A. The
thagomizer. The thagomizer. Yeah. That four -spike
tail is a nasty, nasty weapon. And we found an
Allosaurus tail vertebra, a bone from the base
of the tail, with a massive puncture wound that
goes straight through the bone. A hole. A perfectly
circular hole. And when they measured it, the
shape and size of the hole are a perfect match
for a Stegosaurus tail spike. So an Allosaurus
got smacked. Heart. Right in the tail. Probably
as it was chasing the Stegosaurus. But here's
the kicker. The bone had healed. There was smooth,
rounded bone growth around the hole. The Allosaurus
survived the fit. It limped away from that encounter.
But on the flip side, we have a Stegosaurus neckplate,
one of those big bony plates on its back with
a huge U -shaped bite mark taken out of it. And
that U -shape is a perfect fit for the snout
of an Allosaurus. So these weren't just ships
passing in the night. They were actively brawling.
It was a brutal world. And nothing, absolutely
nothing, illustrates just how brutal it was better
than the story of Big Al. Let's talk about Al,
because usually when we see a fossil, it's just
a cool skeleton. An anatomical specimen. But
Big Al is a biography. He is. He's specimen MOR693,
found in Wyoming in 1991, about 95 % complete,
which is incredible. And he wasn't fully grown,
was he? No, he was a sub -adult. A teenager,
really. Maybe 87 % grown, about 8 meters long.
And when they examined his bones, they found
that this animal lived a life of almost constant
agony. What was the damage report? What did they
find? He had 19 separate pathological injuries.
19 documented traumas. 19. That's unbelievable.
What kind of injuries? Let's see. He had several
broken ribs that had healed, but healed poorly
with big calluses. He had damage to his vertebrae.
But the thing that likely led to his death was
his right foot. The toe infection? The toe infection.
His right middle toe, the main weight -bearing
digit, was massively swollen. It had a condition
called an involucrum. What's that? It's a shell
of new bone that grows around a site of chronic
festering infection. It suggests he had a raging
case of osteomyelitis, a bone infection. So paint
the picture for me. He is walking on this. He's
trying to. Imagine a deep, throbbing infection
in your foot filled with pus, the bone literally
rotting from the inside out. And every time he
took a step, he was putting tons of weight directly
on that infection. The pain would have been blinding.
And he survived with this for a while. The amount
of bone growth suggests the infection was active
for months, maybe as long as six months. How?
I mean, how is that even possible? We just said
this is a high -performance athletic predator.
If you have a severe limp, you can't hunt. You
starve. How does a crippled teenager survive
for six months in the Jurassic? This is one of
the great questions, and this is where we get
into the debate about social behavior. Right.
One theory, the heartwarming one, is that he
had help. Maybe his family, his pack, brought
him food. Maybe they protected him from other
predators while he was vulnerable. The pack theory,
it suggests a level of social care, maybe even
altruism. It does, but I have to say, I'm skeptical.
Why? You don't want to believe dinosaurs had
feelings. I try to avoid anthropomorphizing.
The alternative is that he was just incredibly,
incredibly resilient. Maybe he switched to scavenging.
Maybe he found a drying waterhole with trapped
fish or dying animals he could eat without a
fight. Or bullied smaller predators off their
kills. Exactly. He might have spent those six
months in a state of slow starvation, getting
weaker and weaker, the infection spreading, until
he finally just laid down at a dry riverbed and
never got up. That's where they found him. That
is just. It's a bleak story. But it brings us
to the bigger question. Do they have friends?
We see movies where allosaurs hunt in coordinated
packs like wolves. Is there any truth to that?
The evidence is tricky and very controversial.
The main argument for packs comes from the Cleveland
Lloyd Dinosaur Quarry in Utah. The place we mentioned
earlier. This is the bone bed that's just off
the charts, right? Completely off the charts.
We have found over 12 ,000 individual bones there.
And of all the dinosaurs found, 67 % of the bones
are allosaurus. Two -thirds of all the fossils
are from one species of predator. Yes. We have
the remains of at least 46 individual allosaurus
in one spot. We have babies. We have teenagers
like Big Al. We have full -grown adults. So someone
like Robert Baker looks at that and says, see?
A pack. They lived together. They died together.
Exactly. He argued it was a social group that
got trapped, maybe trying to bring down a large
herbivore that was stuck in the mud. He even
suggested they had lairs and brought food back
to the young. It's a nice image. It is. But modern
interpretations are leaning towards something
else. The predator trap concept is now seen less
as a single event and more like sticky flypaper.
Explain that model. So imagine a seasonal waterhole
that during the dry season turns into a thick,
sticky mud bog. Quicksand, essentially. A herbivore,
like a Camarasaurus, comes to drink. gets stuck
and starts panicking. It's bellowing, struggling.
You have dinner bell. The loudest dinner bell
in the Jurassic. An allosaurus hears it, comes
in for an easy meal and gets stuck itself. Now
you have two dying animals making even more noise.
That attracts more predators and more. They get
stuck, they die, they attract scavengers who
then also get stuck. So it's not a social gathering,
it's a pileup caused by greed. A feeding frenzy
that went wrong for everyone involved. They aren't
there because they like each other, they're there
because they're opportunistic. And possibly cannibalistic.
Oh, yes. There is clear evidence for cannibalism.
We have allosaurus bones from the Morrison Formation
that have bite marks on them, and the spacing
of the serrations in those bite marks perfectly
matches the teeth of other allosaurus. So they
were eating each other. No doubt about it. We
even find shed allosaurus teeth inside the rib
cages of other allosaurus skeletons. This all
supports the Komodo dragon model of social behavior,
the mob. The mob. If you watch Komodo dragons
today, they don't hunt in coordinated packs.
But if there's a carcass, they all converge on
it. They eat together, but it's not friendly.
It's a violent, chaotic hierarchy. The big ones
eat first. If a little one gets in the way, the
big one kills it and eats it too. So if Big Al
was limping around a carcass with a mob of other
allosaurs... He was probably in more danger of
becoming the main course than getting a handout.
It paints a picture of the Jurassic that is much
less... The land before time and much more Mad
Max. A world of just constant, brutal competition.
Exactly. And that competition wasn't just with
their own kind. Let's zoom out a little bit from
the behavior to the neighborhood. The Morrison
Formation Ecosystem. We know Allosaurus was the
most common predator, but it wasn't the only
killer in town. No, it had some very serious
competition. The two other main large theropods
that lived alongside were Ceratosaurus and Torvosaurus.
Torvosaurus. That name just sounds heavy. Savage
lizard. And it was. Torvosaurus was a monster.
It was rarer than Allosaurus, but it was bigger,
maybe 10 meters long, and much more robustly
built. It had a massive skull, huge dagger -like
teeth. If Allosaurus is the wolf or the leopard
of the Morrison... Torvosaurus is the grizzly
bear. Perfect analogy. The brute force apex predator.
And what about Ceratosaurus? Ceratosaurus is
the weird one, the horned lizard. It had a prominent
horn on its nose and two smaller horns over its
eyes. It was smaller than Allosaurus, stockier,
with a very deep, flexible tail that looks almost
crocodile -like, and its teeth were disproportionately
huge. So how do you have three top -tier predators
living in the same zip code without them constantly
fighting and wiping each other out? Niche partitioning.
It's the roommate agreement of nature. I like
that. You take the top shelf, I take the crisper
drawer, and we don't fight over the leftovers.
They were likely specializing in different prey
or different environments. So what was the breakdown?
The general thinking is that Allosaurus was the
generalist. It had longer legs. It was probably
faster. It was adaptable. It likely patrolled
the open floodplains, hunting a wide variety
of prey like Camptosaurus or young sauropods.
And the others. Ceratosaurus, with that flexible
tail and lower -slung body, probably stuck closer
to the waterways, the rivers, and lakes. Maybe
it hunted fish, crocodiles, or ambushed prey
that came to drink. And the bear. Torvosaurus.
Torvosaurus was likely the specialist in hunting
giants. It used its immense size and power to
tackle the largest prey, maybe adult stegosaurs
or subadult sauropods that Allosaurus might have
hesitated to attack alone. But in the end? Allosaurus
won the numbers game. By a landslide. In most
parts of the Morrison, something like 75 % of
the theropod fossils we find are Allosaurus.
It was a coyote of the Jurassic. It could live
anywhere, eat anything, and recover from these
crazy, life -threatening injuries. It was the
ultimate survivor. I have to ask about one more
name before we wrap up because it gets thrown
around a lot. Saurificanax? The lord of lizard
eaters. It sounds like a final boss in a video
game. For a long time, people said this was a
separate, even bigger predator. What's the current
thinking? It's messy, and it's a perfect example
of how science is always updating itself. Saur
faginax was found in Oklahoma from rocks of the
same age. The bones are huge, indicating an animal
over 10 meters, maybe 11 or 12, a true giant.
For years, the debate was. is it its own unique
genus or is it just a really really big allosaurus
what some called allosaurus maximus meaning the
greatest different lizard right but a study came
out very recently in 2024 that threw a massive
wrench in the works they re -examined the holotype
the original defining specimen and found that
it was a chimera a chimera, like the mythological
beast. In mythology, a chimera is a beast made
of different animal parts. In paleontology, it
means the person who collected or described the
bones accidentally mixed up two different animals
and thought they were one. No way. It happens.
It turns out some of the bones originally assigned
to sauropod bones that got mixed in. Big oops.
So the validity of the name sauropod is on very
shaky ground now. However, the actual theropod
bones that are in the mix are distinct enough
from allosaurus to likely be their own species.
So the current thinking is pushing toward renaming
it Allosaurus Anax. Allosaurus Anax, King Allosaurus.
Exactly. It confirms that this body plan, the
hatchet -wielding, loose -skulled, fast -slashing
design, was scalable. It could get truly massive
and challenge even something like Torvosaurus
for the title of heavyweight champion. So when
we step back into our time machine and leave
the Jurassic... What is the lasting image we
should have of Allosaurus? It's not the T -Rex.
It's not the bone crusher. No, it's the slasher.
It's the ultimate opportunist. It's an animal
that lived fast, died young, and threw its body
into the fray with reckless abandon. Think of
Big Al. It survived 19 major traumas. It dominated
its world, not because it was the biggest or
the strongest, but because it was the most adaptable,
aggressive, and widespread engineering marvel
of its time. And for me, the image that's going
to stick is that idea of flesh grazing. It's
so much more terrifying than a clean kill. The
idea of a predator that doesn't even grant you
the mercy of death, but just farms you. It's
a grim world. Nature isn't cruel, but it is profoundly,
deeply indifferent. And for 10 million years,
Allosaurus was the master of that indifference.
Well, on that cheerful note, we're going to wrap
up this deep dive. Whether you're Team Hatchet
Attack or Team Big Cat Clamp, there is no denying
that the Different lizard deserves way more respect
than just being T -Rex's opening act. Absolutely.
A true king in its own right for its own time.
Thanks for listening. Keep those questions coming.
Keep digging. And as always, stay curious. We'll
see you on the next dive.