T. rex vs. Prey: Imagining battles between ancient gladiators

When I was super young, say around five or so, I remember playing in the bath tub with my plastic toys. Some were super heroes like He-Man or Teenage Mutant Ninja Turtles, others were monster trucks and die-cast matchbox cars by Mattel, but most were dinosaurs.

This might be TMI, this story about the kid in the bath tub with bubbles on his head, ramming plastic characters into one another and dreaming up their backstories, the bellows of challenge they traded, and the choreography of their battles, but I know there are other adult children out there with similar memories.

During this epoch in the evolution of me, I distinctly recall pitting Tyrannosaurus rex against Stegosaurus, which, as I’ve discovered in later life, was completely wrong, as was most of what I thought around five years old, but you know, who can blame a five-year-old for muddling up the fossil record?

T. rex is one of the most famous dinosaurs in history, easily identified by its massive, heavy skull, long steak-knife teeth, powerful back legs and tail, and ridiculous vestigial arms, but due to her status as dinosaur royalty, the length of her reign and her identity is as often confused by adults as it is by naive five-year-olds. The T. rex lived for two million years in the Late Cretaceous, never in the Jurassic, as her appearance in Jurassic Park might suggest, but we can forgive this fiction for its oversight. (After all, InGen, the engineering firm responsible for cloning extinct dinosaurs in the movie, infamously mismatched animals from different eras within the same park.) And she wasn’t the only two-legged carnivore.

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In a dramatic representation, Stegosaurus and Allosaurus duke it out in the Jurassic. Morian Hall.

In the time of Stegosaurus, between 155 and 150 million years ago (the real Jurassic), the apex predator was the Allosaurus. Smaller than the T. rex, but with more capable arms with three fingers ending in talons, this baddie no doubt picked battles with Stegosaurus, putting its life on the line for a meal. With its polygonal plates down its back, viciously spiked tail, flexible spine and toes that allowed it to rear up, Stegosaurus could give Allosaurus a true walloping.

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Allosaurus remains feature prominent eyebrow ridges and three-fingered hands with sharp claws.

Forget about jaws and claws. One solid hit from the bone spikes could deeply puncture the neck or torso of any shady Allosaurus looking for a bite, and its plates would protect its spine from being severed by teeth until it could land a blow. It isn’t difficult to imagine eyes gouged and jugulars perforated, many Allosauruses bleeding out after botched predatory encounters with Stegosaurus. There were certainly easier things for Allosaurus to eat, but few battles with other species could match the gladiatorial epicness of this match-up, at least not in this era.

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Even as an herbivore, Stegosaurus would have made a formidable opponent against Allosaurus in the Jurassic, using a spiked tail and bone plates along its spine as defenses.

Fast forward 90 million years to the Late Cretaceous, the reign of the “tyrant lizard.” Tyrannosaurs roamed North America and Asia, preying on a variety of other famous megafauna like Triceratops, Ankylosaurus, and duck-billed hadrosaurs including Edmontosaurus, Brachylophosaurus, and Parasaurolophus. There’s no way T. rex even knew Stegosaurus was a thing. More time passed between these two than between dinosaurs and Homo sapiens.

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As the largest predator of the Late Cretaceous, the T. rex is one of the fossil record’s most iconic species.

Nor was the T. rex the only one of her kind; she was just the largest, hence the name, “king of tyrants.” Among her smaller contemporaries, Tarbosaurus, Albertosaurus, Daspletosaurus, and Gorgosaurus, she was the Queen B, big and bad, in spite of the competition. She had excellent vision, a sense of smell that could detect prey from miles away, and decent hearing, though high-pitched sounds would have been lost to her. Food wouldn’t have been difficult for the T. rex to find, but that food really, really didn’t want to be eaten.

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T. rex couldn’t have fought Stegosaurus, but it preyed upon Triceratops, another iconic species that lived in the same time period.

There’s no more famous match-up than Tyrannosaurus rex and Triceratops. With two long horns and a bony frill like a samurai helmet to guard its neck, as long as the trike met the T. rex head-on, there was no contest. But if Triceratops charged and missed the mark, the tyrant’s big jaws could take out its backbone in a single bite, neutralizing the threat of horns. Recent discoveries of casts of Triceratops‘s hide reveals nodules that might have housed quills, making even a bite to its back a dangerous one if T. rex ever got around the impenetrable helmet. You can imagine this battle yourself in the Morian Hall of Paleontology, where Lane the Triceratops takes a defensive position under an aggressor T. rex.

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T. rex preyed upon Denversaurus and its famous cousin, Ankylosaurus, but both would have made a difficult meal, protected by bony armor.

Against Ankylosaurus and its cousin Denversaurus, also on display in Morian Hall, tyrannosaurs likely had a more difficult time. Both Ankylosaurus and Denversaurus developed the adaptation of a wide, low body and armored plating, making access to its soft underbelly impossible for tyrannosaurs unless kicked onto its back, but Ankylosaurus had another advantage. The tip of its tail bore a mace-like club that, like Stegosaurus’s spiked tail, could maim the jaws of predators that didn’t pay enough heed. One swing from this heavy weapon could break open a T. rex‘s face, cripple its legs, or shatter its ribs, and with arms too small to defend itself, dodging seems the only tactic at her disposal against this tank of a creature. An encounter with an Ankylosaurus could mean either a meal or certain death, depending on the T. rex‘s experience hunting.

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Armor plating on the back of Denversaurus would have protected against a bite from the T. rex and other tyrannosaurs of the Late Cretaceous, but if flipped over, its soft underbelly would be exposed.

A more easy meal for any tyrannosaur would have been Edmontosaurus and other duck-billed dinosaurs. These hadrosaurs had few defenses. No armor plating, no spikes, no claws, no wings, no sharp teeth. But it’s possible they had a different advantage, though it’s tough to deduce through fossils alone. Hollow chambers in the skulls of many hadrosaurs suggest these creatures, like geese and other water fowl, had the power of sound at their disposal. A deafening bellow might have stopped a tyrannosaur in its tracks or sent it running in the other direction. T. rex isn’t known for its sensitive hearing, but as we all know, if the sound is loud enough, it can be excruciating. And T. rex had no fingers to put into her ears, nor could she reach them.

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Edmontosaurus, a duckbilled hadrosaur and cousin of Parasaurolophus, appears to have lacked natural defenses. However, the hollows in its skull suggest it could have protected itself with deafening bellows like giant geese.

Understanding these species as they once were, interacting with one another, is more than bath tub child’s play for paleontologists; it’s a career and a discipline. It’s in the Greek roots of the word “paleontology,” the study of being and beings in the ancient world. The study of what life on Earth might have looked like eons ago. The work of these scientists is more like philosophy than fiction, but building careful theories via the fossil record and considering every angle does require a measure of imagination.

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An artist’s representation depicts Triceratops and Tyrannosaurus rex in an age-old feud set in the lush swamps of the Late Cretaceous, an imagined scene deduced from evidence in the fossil record. Morian Hall.

I suppose, apart from the spikes and teeth and horns and claws and body armor and all the other things that make these terrible lizards seem like something out of science fiction, or monsters invented by a puppeteer, it’s the daydreaming paleontology requires that holds my attention. To understand their world, you must build it in your mind.

Wait a second. Why did dinosaurs have tails?

Question: Why does T. rex have such a big tail?

Answer: The tail is a counterbalance, so the body doesn’t come crashing down.

Everyone knows this is the right answer. All the books in the volunteer library say so. We’ve been telling kids this since 1907 (or thereabouts).

You can do an experiment. Go to the Museum Store. Buy a plastic T. rex. Cut off the tail with your Leatherman. Watch the plastic T. rex fall. See? Case closed.

Bakker - Tail Blog 1Dr. Bob does say that’s the right answer. But he also says it is the totally wrong answer.

Dang PhD! Doesn’t he know we have to talk to 35 fourth-graders all at once in our Fossil Hall? We need simple, direct answers, not some sort of Talmudic rumination that goes around in circles and ties itself in knots like a philosophical pretzel.

Wait. He does make a good point or two.

First point: Dino tails were made of live bone and thick muscle, tissue that’s expensive for any animal to make. To grow his massive tail, a rex would have to eat lots more protein and minerals than what he would need if he were tail-less. Any rex who could do away with his tail would save 35 percent of his total food bill.

If the only purpose of the tail is to be dead weight that balances the body in front of the hips, it seems silly to build the tail out of such costly material.

Second point: Consider the turkey. Or a free range chicken or ostrich. Or Texas roadrunner. They are just as bipedal as a tyrannosaur or allosaur but they have hardly any bone or muscle in their stubby little tails (tail feathers are very light and inexpensive).

Go out to a farm and chase chickens and turkeys. Come to Seymour and try to catch a roadrunner as it zig-zags between the cactus. You will discover that these nearly tail-less critters run around and maneuver quite efficiently — and hardly ever fall over on their beaks.

Bakker - Tail Blog 2If evolution can make a bird who balances perfectly without a heavy tail, why would Darwinian processes insist on giving dinosaurs such wasteful rear ends? Let’s walk through the history of tails to see how function shifted over the last 380 million years.

Stage One: The Earliest Amphibian, the First Vertebrate with Legs and Toes Fit for Walking.

We trust you’ve been watching “Your Inner Fish” on TV. Go read the book. It’s a great story about how the earliest four-legged fossils were dug in Greenland, stubby-limbed fellows named Icthyostega and Acanthostega. These species retained some very fishy features, like internal gills, tail fins designed for swimming, and heads that had no way to hear airborne sound waves. They did have thick, strong thigh bones (femora) with large joints for the hip socket and knee.

Bakker - Tail Blog 3On the back of the thigh bone is a bump where a major muscle attached — it is the “tail-thigh muscle”, or, if you’re a fossil geek, you can use the Latin caudo-femoralis. Reptiles today have that muscle, as do salamanders.

Next time you are in Grand Chenier, La., go to the Cajun restaurant and order gator tail. The big chunk of meat you are eating is the tail-thigh muscle. It’s immense. It attaches to the side of the tail bones and then runs forward to attach to that bump on the thigh bone.

(More fossil-jargon for paleo-nerds: muscle bumps on the thigh are labelled “trochanters”, and the tail-thigh muscle is hooked onto the “fourth trochanter.” No, I’m not going to explain the other three trochanters; if you must know, get Al Romer’s The Vertebrate Body).

When the tail-thigh muscle contracted in Ichthyostega , it pulled the hind limb back and pushed the body forward. In other words, the tail-thigh muscle was one of the main propulsive organs that let the earliest four-legged animals walk. Top speed wasn’t fast; more of a steady waddle.

Stage Two: Early Reptiles, about 300 million years ago.

Early reptilian legs were much longer than in the early amphibs, and the beasts were far more nimble. The tail-thigh muscle still was the No. 1 propulsive unit, pulling back on the fourth trochanter in every step. The end of the tail was very long and whip-like, so it could be used as a weapon to slap other reptiles or inquisitive amphibians who got too close.

Bakker - Tail Blog  4Stage Three: Land Crocs, Close Kin of Dinosaurs, about 210-250 million years ago.

A major upgrade in running equipment came in the Triassic with the evolution of land crocs (technical label: the “suchia,” from the Greek word for croc). Land crocs did include the direct ancestors of today’s water-loving crocodiles and alligators, plus a dazzling array of land-lubbers. Leg action was even stronger than in the earliest reptiles, and the tail-thigh muscle was of great size.

Footprints show that most types of land crocs walked on all fours. However, the hind limbs were much, much thicker and longer than the front, so the tail-thigh muscle was dominant in thrusting the animals forward, with only a little help from the forelimb.

Bakker - Tail Blog 5Land crocs filled the Middle and Late Triassic with a dynamic horde of adaptive variations — we have three examples in the Morian Hall of Paleontology. There were huge predators with heads over a yard long, armed with saw-edged fangs (Postosuchus), who used their hefty tail-thigh muscles to generate fast running speeds. And there were armor-plated plant-eaters (Desmatosuchus) who employed their tails to brace the forequarters when the up-turned snout was busy excavating roots and tubers. And there were immense fish-eaters with long snouts bristling with stabbing teeth up front and, in the rear, steak knife teeth for cutting prey (Smilosuchus and its cousin Rutiodon). These aquatic species developed deep, flat-sided tails that were useful for swooshing underwater, providing locomotion a la croc or a la gator.

Bakker - Tail Blog 6Here are two land crocs featured in our Fossil Hall. The spiky fellow is Desmatosuchus, an herbivore. The big-headed chap is Postosuchus, a predator. Both are common fossils in the Triassic Red Beds of Texas and adjacent New Mexico.

Bakker - Tail Blog 7And here’s Rutiodon, a land croc who modified the tail into a swimming organ. Our Smilosuchus is a close kin. The drawing is by the great S. W. Williston for his delightful book, Water Reptiles of the Past and Present. Williston did all his own illustrations — my hero!

Stage Four: Carnivorous Dinosaurs, about 200 million years ago.  

The first genuine dinos evolved from a quadrupedal ancestor shaped like a Land Croc. The dinos took the trends in limb evolution to extremes. They reduced the size of the front legs even more, and increased the length and thickness of the hind. Voila! The early meat-eating dinosaurs were completely, unapologetically bipedal. Since the tail was already very heavy, it found employment balancing the forequarters.

My old professor Stephen J. Gould would label this event as an “exaptation.” That’s when an organ first evolves to fulfill some initial function — in this case, the tail-thigh muscle developed to power the hind limb stroke — and then, later, turns out to be useful in a new role: balancing.

Bakker - Tail Blog 8See! The long tail of bipedal dinosaurs did NOT first evolve as a counterbalance.

It first evolved in strictly quadrupedal animals, the earliest fishy-oid amphibian. The tail was the attachment for the tail-thigh muscle, a key unit of the hind limb stroke. The tail remained very important in walking and running in early reptiles and then in the close kin of dino ancestors, the quadrupedal land crocs. The first dinos were similar to land crocs except the hind legs were bigger and the fore legs smaller. Since they already had a super-heavy tail, the dinos were equipped to shift into a strictly bipedal style.

Yes, the T. rex tail served as a counterbalance. But all through the evolution of rex ancestors, going back to 380 million years ago, the tail’s main purpose had been as an attachment site for the super-sized tail-thigh muscle.

Where Night at the Museum Goes Wrong. And Black Labs Go Right.

I love the Night at the Museum movie, especially the T. rex skeleton that comes to life. However … the rex does illegal things. He wags his tail like a dinosaurian bloodhound or Labrador retriever.

Wrong. Since the tail-thigh muscle was thick and attached to the thigh, rex-like dinos couldn’t twitch, flip, wag or otherwise wiggle their tail with quick movements. Crocs and lizards have the same limitation: powerful sweeps of the tail are fine, but twitchy movements are impossible.

That’s why pet gators don’t wag their tails — even if you throw them a frisbee.

Bakker - Tail Blog 9Hmmmmmmm … that brings up a mystery. We mammals evolved from an ancestor very close to Dimetrodon, the fin-back reptile of some 285 million years ago. D’dons had thigh bones with huge fourth trochanters, where the tail-thigh muscle attached. And that means the tail was linked to the hind limb and incapable of rear-end wiggle-ness.

Modern mammals are weird. None of us has any connection between a tail muscle and the thigh bone, not even big-tailed species like otters, platypuses, pangolins * or giant red kangaroos. Somewhere between Dimetrodon and the earliest true mammal of the Triassic, our ancestors lost the thigh-tail linkage.

How can we tell when it happened? And how can we tell why it happened? It’s not a rhetorical question — I don’t know for sure. No one does. But I do have a hunch …

Bakker - Tail Blog 10*Don’t know what a pangolin is? “Scaly anteater” is another common name. Google it.

The votes have been tallied: Your new mascot is called…

Tiny the Tyrannosaurus rex!

You all sure appreciate a sense of irony — Tiny won our naming contest with 104 votes over Tex’s 85. The remaining nominated names trailed behind, with Huey coming in at 19 votes, Sam with 10 and Amigo with eight.

We’ve gotta say, we were pulling for Tiny all along. Just look at him; it’s perfectly paradoxical:

T-Rex trying to crack a geode!
Tiny the T.Rex is having trouble cracking this geode. He should come to HMNS’ geode-cracking station!

The winning name was first nominated by Katy Yeager Huggins, who won four passes for a guided tour of the new Hall of Paleontology. Congratulations, Katy!

Tell us: What do you think of Tiny the T. rex?

Help us help you: Name our new paleontological pal and win a guided tour of the new Hall of Paleontology!

By now you all should be acquainted with our new mascot:

T-Rex Trying to fit in!

He’ll be hanging out with us for the indefinite future, and it occurred to us that it might be polite to give him a name.

Well, that hasn’t gone smoothly, as you might imagine. In fact, the entire process reminds me of the infamous family shutout of ’92, when my sister was incubating and my two name suggestions — Maleficent for a girl, Pooch Patrol for a boy, naturally — were vetoed without so much as a vote.

Although in hindsight I think “Annie” does have a nicer ring, I’m dedicated to making this naming exercise a touch more fair. And that’s where you guys come in!

Here are the contest details: Leave a comment either here or on HMNS’ Facebook page with your suggestion of a name for our new spokes-dino. The top five submissions (read: our most favorite) will be selected by our online team, and then put to a vote on Facebook. The winner will get a guided tour for four of the new Hall of Paleontology — with more than 3 billion years and hundreds of species to cover, don’t you think you want a docent?

The power of social media is yours to harness, so use it!

The name nomination contest ends Friday at 5 p.m., so get your thinking caps on and come up with something our tireless T. rex can be proud of — just don’t ask him for a high five.