Ankylosaurus

Impenetrable Defense and the Ultimate Weapon

The greatest strength of Ankylosaurus was its thorough defense.
Its back was covered in a hard, bony shield (osteoderms), like a suit of armor, from which countless horns protruded.
The bones of its skull were also thick, and it even had bony armor over its eyelids, leaving almost no weak points.
This impenetrable defense was like an “unassailable moving fortress.”

An unassailable moving fortress

It is believed that even a large carnivorous dinosaur like Tyrannosaurus would have hesitated to attack a fully grown Ankylosaurus.

Furthermore, at the end of its tail, Ankylosaurus had a giant mass of bone, a hammer known as a “tail club.”
The bones in the latter half of the tail were fused together, forming a stiff handle for swinging the hammer.
This allowed it to swing the club from side to side at a powerful speed, using the flexible muscles at the base of its tail.

It could swing the hammer from side to side at a powerful speed

According to a 2009 study, a single blow from this hammer could generate a force of up to 364 to 718 MPa (megapascals), which was powerful enough to shatter the leg bones of a Tyrannosaurus.
The height of the tail was right at a Tyrannosaurus’s knee, so a direct hit could inflict serious damage.
Ankylosaurus compensated for its weakness of being a slow walker with this hard armor and powerful weapon, allowing it to thrive for millions of years.

A Mysterious Full Body and a Unique Diet

Despite being so famous, no complete skeleton of Ankylosaurus has ever been discovered, making it a dinosaur shrouded in mystery.
Our knowledge of its appearance is a reconstruction based on fragmentary fossils like skulls and armor, as well as research data from its close relative Euoplocephalus, for which a more complete fossil record exists.

Ankylosaurus was a herbivore with a beak-like snout.
Its teeth were small and weak, so it could not chew hard plants. It appears to have eaten plants, such as ferns, by plucking them with its wide beak and swallowing them almost whole.
According to a 2017 study, it is estimated to have needed about 60 kg of ferns per day.

It is estimated to have needed about 60kg of ferns per day

The Secret of Its Surprising Skull and a History of Success

A CT scan of an Ankylosaurus skull revealed a complex interior of its nasal passages.
The air passage deep inside its nose was divided into eight small chambers, leading to the interesting theory that it functioned as an “air conditioner” to warm and humidify inhaled air, or as a “resonating chamber” to produce loud calls.

Ankylosaurus is one of the most famous dinosaurs of the late Cretaceous period, but one reason a complete skeleton has not been found in over a century is the theory that its population was originally very small.
If this theory is correct, it means that they lived with a limited population even in their heyday.
As evidence, no Ankylosaurus fossils have been excavated from the very end of the Cretaceous period, leading some to believe that it was one of the few dinosaur species that “did not witness the moment of mass extinction.”