Ankylosaurus vs Stegosaurus: What Are the Differences?

Ankylosaurus in Forest
© Daniel Eskridge/

Written by Kyle Glatz

Updated: June 22, 2022

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When most people think of dinosaurs, they imagine the massive carnivores like the T-Rex. However, some of the most interesting and relatively mysterious dinosaurs are herbivores, like the Ankylosaurus. With its armored body and the club on its tail, it was certainly an interesting reptile. The Stegosaurus is another cool, spiky dinosaur with a dangerous tail. Today, we’ll take a close look at the Ankylosaurus vs Stegosaurus and show you how they’re alike and different.

If you’ve spent most of your time focusing on the big apex predator dinosaurs, you’ll gain a whole new level of respect for the smaller plant-eaters.

Comparing an Ankylosaurus and a Stegosaurus

Ankylosaurus  vs Stegosaurus
Ankylosaurus and Stegosaurus both made good use of their tails for defense.
SizeWeight: 11,000lbs-18,000lbs Height: 4.5ft-5.6ft at the hip, closer to 7ft tall overall
Length: 20ft-33ft
Weight:11,000lbs -15,400lbs Height: 7ft-9ft at the hip, 14ft tall overall
Length: 20ft-30ft
Morphology– A relatively short creature with bony plates covering its body
– Bony plates that protruded from the sides and flank
– Had a long tail with a bony club at the end
– Exceptionally small head for its body size and an unusually small brain for a dinosaur
– Had up to 22 dermal plates that rose from their back which may have been used for defense – Had a long tail with a “thagomizer” on the end (a series of four spikes)
Era– 70 to 66 million years ago– 155 to 145 million years ago
Eating Habits– Herbivore that probably ate soft plants and fruits– Herbivorous  
Attacking Methods– May have used its tail club to hit others
– Could have rammed prey with its head
Bony plates called osteoderms  acted as armor for the dinosaur – Spiky protrusions coming from the animal’s flanks
– Thick, armored skull
– Would swing its tail and slam its spikes into predators  

The Key Differences Between an Ankylosaurus vs Stegosaurus

The most important differences between the Ankylosaurus and the Stegosaurus include their morphology and the era in which they lived. The Ankylosaurus is an herbivorous quadrupedal dinosaur that lived as few as 66 million years ago with a heavy body covered with bony plates that ended in a tail with a bony club on its end, and the Stegosaurus was a tall, heavy dinosaur that lived 145 million years ago that weighed up to 15,000lbs and was known for having almost two dozen dermal plates standing on its back and a long, spiky tail.

In some ways, these animals sound the same, but they’re actually quite different when they’re closely examined. We’ll show you the ways that these spiky creatures are unique.

Ankylosaurus vs Stegosaurus: Size

The Ankylosaurus was larger than the Stegosaurus by most measurements. For example, Ankylosaurus could weigh up to 18,000lbs, stand 7ft tall, and grow up to 33ft long. Stegosaurus would stand taller at about 14ft, counting its dermal plates, grow about 30ft at its maximum, and weigh up to 15,400lbs.

The Ankylosaurus was certainly stouter and kept its massive body lower to the ground than the Stegosaurus.

Ankylosaurus vs Stegosaurus: Morphology

Both the Ankylosaurus and the Stegosaurus are known for their body armor, but each dinosaur had a different deployment of these plates. The top of the Ankylosaurus’s body was covered with osteoderms that provided a lot of protection from attacks. The plates extended outward from the dinosaur’s body as well, creating a spiky edge that could deter attackers. The dinosaur’s tail ended in a thick bony club.

Stegosaurus had a very small head for its size and an exceptionally small brain. However, the large dinosaurs back had somewhere between 12 and 22 dermal plates that erupted vertically from their back. These bony, somewhat sharp plates could have been used for defense or thermal regulation.

The Stegosaurus’s tail was long and ended in what has come to be known as a thagomizer, a series of four long, sharp spikes used to ward off foes. Stegosaurus had a back covered in vertical standing plates and a spiky tail, while Ankylosaurus had a thick bony tail and flat armor plates.

Ankylosaurus vs Stegosaurus: Era

The Ankylosaurus was among the last dinosaurs to live on the Earth, going extinct about 66 million years ago at the end of the Cretaceous Period following the Chicxulub asteroid impact. Stegosaurus was long extinct by that time, living sometime between 155 and 145 million years ago.

Ankylosaurus vs Stegosaurus: Eating Habits

Both the Ankylosaurus and the Stegosaurus were herbivores. Ankylosaurus may have eaten small invertebrates as well, but scientists aren’t certain about that.  

Ankylosaurus vs Stegosaurus: Attacking Methods              

Ankylosaurus used its thick tail to smash enemies.


The Ankylosaurus and the Stegosaurus were both herbivores, so they didn’t hunt other dinosaurs. However, they still had to defend themselves against some carnivores that shared their ranges. That means they had to know how to fight.

The Ankylosaurus had great defenses that made it hard to find a soft spot and even harder to flip over. The dinosaur’s most likely defense was using its tail to smash into predators, knocking them down or breaking bones.

The Stegosaurus was similar to the Ankylosaurus in this manner. This dinosaur would also use its tail to attack predators. Its tail was not as heavy. Instead, it would swing its tail with the four spikes at its foes. Each of these spikes could be between 2 and 3 feet long, and they may have been horizontal or vertical on the tail. That could cause a tremendous amount of damage and even prove fatal to some dinosaurs.  

The tail whip theory is debatable, but it does have some proof. A very valuable Allosaurus vertebra showed signs of damage and healing from an object that was very consistent with a Stegosaurus’s tail spikes. In other words, a stegosaurus managed to successfully land a tail strike against a larger predator dinosaur.

Ankylosaurus vs Stegosaurus: Who Would Win a Fight?

Stegosaurus in Forest

Stegosaurus has more offensive power to win a battle between the herbivores.


A Stegosaurus would win a fight against an Ankylosaurus. Ankylosaurus has a powerful blunt weapon on the end of its tail, and that could deal some damage to the Stegosaurus. However, beating a Stegosaurus to death or breaking its legs is going to take some serious power and a bit of luck.

Meanwhile, a Stegosaurus has spikes on its tail that measure 2 to 3 feet long. A swooping swing of its tail could puncture the less-armored side of the Ankylosaurus’s head or smash into its side.

The battle would likely boil down to which animal is bigger at the time of the fight, as well as who lands the first damaging blows. Once one of these dinosaurs takes major damage to its legs or body, it’s all downhill.

The Ankylosaurus and Stegosaurus may be easy to confuse for one another. They both have unusual tails and spiky plates on their bodies. Nevertheless, they looked very different, had unique body compositions, and lived millions of years apart in time. They never roamed the Earth together.  

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About the Author

Kyle Glatz is a writer at A-Z-Animals where his primary focus is on geography and mammals. Kyle has been writing for researching and writing about animals and numerous other topics for 10 years, and he holds a Bachelor's Degree in English and Education from Rowan University. A resident of New Jersey, Kyle enjoys reading, writing, and playing video games.

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