Ankylosaurus

Basic Information

Ankylosaurus means “fused lizard” because many of its bones were joined together to make its body super strong!

Ankylosaurus lived during the Late Cretaceous period, about 68 to 66 million years ago, right up until the extinction of the dinosaurs!

The first Ankylosaurus fossil was discovered by Peter Kaisen in 1906 in the Hell Creek Formation near Gilbert Creek, Montana.

A full-grown Ankylosaurus was as long as a school bus (20–30 feet) and weighed as much as one or two elephants (8,000–17,600 pounds)!

Ankylosaurus belongs to a family of dinosaurs called Ankylosauridae, and they were all heavily armored plant-eaters!

Scientists think Ankylosaurus could only run about 6 miles per hour (10 km/h), which is about as fast as you can ride a bike when you’re first learning!

Ankylosaurus fossils have been found in western North America, from Montana to Alberta, Canada!

The most complete Ankylosaurus fossil found is nearly whole, with a well-preserved skull, tail club, and much of its body!

Physical Features

Ankylosaurus had bony plates called osteoderms covering its entire body, making it look like a walking tank!

The skull of an Ankylosaurus was incredibly thick — up to 2 inches (5 cm) of solid bone protected its tiny brain!

Ankylosaurus had small, leaf-shaped teeth perfect for crushing tough plants, and they were replaced regularly throughout its life!

The famous tail club of Ankylosaurus was made of several vertebrae fused together and covered in thick bone, making it as hard as concrete!

An Ankylosaurus tail club could weigh up to 40 pounds (18 kg) — that’s about as heavy as a big dog!

The nostrils of Ankylosaurus were huge and curved, which might have helped it smell predators coming or find the tastiest plants!

Scientific Understanding

Paleontologists can tell how old an Ankylosaurus was when it died by studying growth rings in its bones, just like counting rings in a tree trunk!

Habitat & Environment

Ankylosaurus lived in a warm, humid climate with lots of rivers and forests, similar to parts of Louisiana today!

The plants that Ankylosaurus ate included ancient relatives of magnolias, palm trees, and ferns — some of which still exist today!

Ankylosaurus shared its habitat with Tyrannosaurus Rex, Triceratops, and many other famous dinosaurs!

Scientists have found fossilized plants in the same rock layers as Ankylosaurus bones, helping us understand exactly what their world looked like!

Ankylosaurus lived in areas with seasonal rainfall, and they might have migrated to find food during dry seasons!

Fun and Unique Facts

Baby Ankylosaurus were probably born with soft armor that hardened as they grew up, just like a turtle’s shell!

An Ankylosaurus probably spent most of its day eating — it needed to consume hundreds of pounds of plants every day to maintain its huge body!

Ankylosaurus used its wide beak like a lawn mower to crop low-growing plants close to the ground!

Scientists think Ankylosaurus might have made low-frequency sounds that traveled through the ground to communicate with each other!

The tail club of an Ankylosaurus could swing with enough force to break the leg bones of a T. Rex!

The armor plates on Ankylosaurus were arranged in different patterns that might have helped them recognize each other!

Ankylosaurus had special eyelids made of bone that could close to protect their eyes during fights!

In 2019, scientists discovered that Ankylosaurus armor had blood vessels running through it that might have helped control their body temperature!

A baby Ankylosaurus was probably about the size of a large dog when it hatched!

The largest Ankylosaurus specimens were as wide as a small car and needed strong leg muscles to support their weight!

An adult Ankylosaurus’s head was about the size of a kitchen garbage can!

We know Ankylosaurus had keratin covering their armor plates because scientists found evidence of protein structures in their fossils!

Footprint fossils show us that Ankylosaurus walked with their legs directly under their body, like modern elephants!

Some Ankylosaurus fossils show healed injuries, telling us that they survived attacks from predators!

Tooth marks found on some Ankylosaurus armor plates show that T. Rex tried to attack them but often failed!

Footprint fossils show that Ankylosaurus sometimes walked along the same paths as Triceratops!

Scientists use special X-ray machines to look inside fossilized Ankylosaurus bones without damaging them!

Paleontologists make 3D computer models of Ankylosaurus skeletons to study how they moved!

Scientists study modern animals like armadillos and crocodiles to better understand how Ankylosaurus armor worked!

The bony plates in Ankylosaurus skin were arranged in different layers, like wearing multiple suits of armor!

Ankylosaurus had strong leg muscles that helped them push off the ground quickly if they needed to turn and swing their tail!

Some Ankylosaurus fossils have been found with the remains of their last meal still preserved in their ribcage!

As Ankylosaurus grew, new armor plates would form in their skin to cover their expanding body!

Young Ankylosaurus had proportionally bigger heads and eyes compared to their body size, just like baby mammals today!

The tail club of an Ankylosaurus didn’t fully develop until they were several years old!

Fossilized plant remains found near Ankylosaurus teeth show they ate both soft leaves and woody stems!

Ankylosaurus had cousins called Euoplocephalus that had different shaped tail clubs and armor patterns!

A relative of Ankylosaurus called Nodosaurus had spikes along its sides but no tail club!

Scientists have found armored dinosaur relatives of Ankylosaurus in Mongolia called Tarchia!

Some of Ankylosaurus’s earliest relatives were much smaller, about the size of a large dog!