T-Rex vs Ankylosaurus: What Are the Differences?

Written by Kyle Glatz
Published: May 9, 2022
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The Cretaceous was a geological period that started about 145 million years ago and lasted until almost 66 million years ago, the time when dinosaurs died out. During this last age of massive terrestrial fauna, the T-Rex was still stomping around and eating smaller dinosaurs. Among the other gargantuan reptiles that existed during this time was the armor-laden Ankylosaurus, a heavy dinosaur just trying to find enough plants to survive. Let’s take a look at the T-Rex vs Ankylosaurus and see how these dinosaurs were alike and what set them apart.

Comparing a T-Rex and an Ankylosaurus

T-Rex and Ankylosaurus have different habits.
SizeWeight: 11,000-15,000lbs Height: 12-20ft
Length: 40ft
Weight: 11,000lbs-18,000lbs
Height: 4.5ft-5.6ft at the hip, closer to 7ft tall overall
Length: 20ft-33ft
Morphology– Bipedal
– Massive legs, small arms
– Large head and skull
– 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
Era– 90 to 66 million years ago– 70 to 66 million years ago
Eating Habits– Carnivorous
– Either a hunter or scavenger
– Herbivore that probably ate soft plants and fruits
Attacks– Killed prey using its massive 17,000lbf bite power
– 50-60 D-shaped serrated teeth
– 12-inch teeth
– 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 skull, armored head

The Key Differences Between a T-Rex vs Ankylosaurus

Ankylosaurus had powerful defenses and a tail that could deliver bone-crushing blows.


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The greatest differences between a T-Rex and an Ankylosaurus are their morphology and eating habits. The T-Rex was a bipedal, thick-legged, carnivorous dinosaur that weighed up to 15,000lbs, stood up to 20ft tall, and measured 40ft long, and the Ankylosaurus was a relatively short quadrupedal herbivore that was covered in osteoderms and had a long tail with a thick bony club on its tail.

These are the primary differences between a T-Rex and an Ankylosaurus, but they are not the only differences. We will explore both dinosaurs in greater depth in the rest of this article.

T-Rex vs Ankylosaurus: Size

The T-Rex is taller and longer than the Ankylosaurus, but it may not always have weighed more. The Ankylosaurus could weigh between 11,000lbs and 18,000lbs, stood about 5.6ft at the hip or 7ft overall, and could measure 33ft long.

Tyrannosaurus Rex could grow up to 15,000lbs, stand anywhere from 12ft to 20ft tall, and measured 40ft long at its utmost. Depending on how large the dinosaur grew, it could beat the Ankylosaurus in every measurement.

T-Rex vs Ankylosaurus: Morphology

The T-Rex is known for being a biped with large legs, a massive head, strong jaws, and immense teeth. A T-Rex’s teeth could measure about 12 inches long, more than enough to fatally bite most creatures. In a unique twist of evolution, the T-Rex had very short arms.

Ankylosaurus walked on four legs, and the top of its body was protected with armor plates made of a tough material called osteoderms. Ankylosaurus also had bony plates jutting from its sides and flank, as well as a bony club on the end of its tail. This is one of the most unique-looking dinosaurs of the era.

T-Rex vs Ankylosaurus: Era

The T-Rex and the Ankylosaurus both lived until the end of the Cretaceous Period, a time lasting from 145 million years ago until about 66 million years ago. This era was ended by the Cretaceous-Paleogene extinction event when much of life was wiped out on the planet from an asteroid impact.

Before that, though, T-Rex is believed to have lived from 90 million years ago until the extinction event. The Ankylosaurus lived at least from 70 million years ago until 66 million years ago. These animals shared an era as well as a location in North America.

T-Rex vs Ankylosaurus: Eating Habits

The T-Rex is one of the most famous carnivores in the realm of dinosaurs. However, scientists are not entirely certain whether the T-Rex was exclusively a hunter or if it spent time as a scavenger.

The same uncertainty applies to Ankylosaurus. This dinosaur was probably herbivorous based on its beak and teeth, but it could have easily snacked on other smaller creatures, too. After all, it needed to ingest a lot of calories if it was going to survive.

T-Rex vs Ankylosaurus: Attacks

The T-Rex was a very powerful one-trick animal. It would spot a creature, stomp on over to it, and then bite it with its immensely powerful jaws. The T-Rex could exert 17,000lbf on its prey, driving about 60, 12-inch teeth into the creature. These D-Shaped teeth would slice through flesh with ease, helping the T-Rex kill its foes and pick them clean.

The Ankylosaurus was far more defensive than the T-Rex. That doesn’t mean it was helpless, though. This dinosaur could use its weight and bony protrusions to great effect, charging and trampling foes. Other than that, it’s believed that the dinosaur would use the large bony club on the end of its tail to ward off or harm predators.

T-Rex vs Ankylosaurus: Who Would Win in a Fight?

Giganotosaurus vs T-Rex - T Rex hunting

T-Rex was one of the most dangerous dinosaurs to walk the planet.

©Herschel Hoffmeyer/Shutterstock.com

The T-Rex would most likely kill an Ankylosaurus in a fight. It may take a while, though. The T-Rex has powerful jaws, and that might be enough to bite through the osteoderms that protect the smaller dinosaur’s body. Of course, several bites may be needed to deal a fatal blow through the armored body of the other dinosaur.

Otherwise, the T-Rex would need to grab and flip the other dinosaur over and then bite it, a tall task indeed. The T-Rex probably wouldn’t walk away from the fight unscathed. A few bashes from the tail or the T-Rex biting down on the wrong part of the Ankylosaurus’ body would be painful and damaging.  

At the end of the day, though, it’s far more likely that the apex predator T-Rex would manage to kill the Ankylosaurus than the other way around.

The photo featured at the top of this post is © Orla/Shutterstock.com

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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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