Dinosaur with tail ball

Ankylosaurus magniventris, facts and photos

Famous for its clubbed tail, Ankylosaurus roamed North America some 70 million to 66 million years ago in the late Cretaceous period.

Stocktrek Images/Nat Geo Image Collection

Please be respectful of copyright. Unauthorized use is prohibited.

Ankylosaurus magniventris was the prehistoric tank of the late Cretaceous period, some 70 million to 66 million years ago. This enormous four-legged dinosaur had a squat body covered with bony plates that were studded with spikes. At its tail, the plates fused together to form a thick club that the dinosaur could swing to fend off threats.

This impressive defense offered Ankylosaurus protection from large land predators such as Tyrannosaurus rex, which also roamed North America around this time. Would-be predators would have had to flip this armored dinosaur over to reach its broad underbelly—its only weak spot.

Relatives

Ankylosaurus magniventris is an ankylosaur—a suborder of four-legged, armored, and mostly herbivorous dinosaurs—but not all ankylosaurs were Ankylosaurus. This dinosaur is the namesake of its suborder, which included both ankylosaurids and the more primitive nodosaurids. Ankylosaurus magniventris was the last and largest species of ankylosaurid. The dinosaur grew up to 33 feet long and probably weighed about four tons. Its size—combined with its small teeth and oddly placed nostrils—make this species one of the more unusual ankylosaurs.

While nodosaurs share the armor and tank-like build of Ankylosaurus, they did not have the dinosaur’s clubbed tail. In 2011, the unearthing of a remarkably well-preserved nodosaur fossil—one of the best ever found—offered new insight into the nodosaur’s pigmentation, which may have served as camouflage, as well as the size and shape of its armor. The discovery of a fossilized ball of digested plant matter in this animal’s stomach also confirmed what researchers had suspected about armored dinosaurs: They preferred to graze on ferns and other low-growing plants.

Ankylosaurus had a narrow beak at the end of its skull to help it strip leaves from plants. It also had small, leaf-shaped teeth, which may have been useful for gnashing small fruits or invertebrates, and a large gut for digesting the large quantities of plant matter necessary to sustain its formidable body.

Evolving fossil knowledge

Though Ankylosaurus is among the most famous dinosaurs, it is also one of the most puzzling. Unlike its nodosaur relatives, scientists have only unearthed a handful of Ankylosaurus fossil fragments, and with each new discovery, our understanding of the species grows. Paleontologists have rearranged the available fossils time and again, with the most recent proposed body shape suggesting it may have been longer and thinner than previously thought, and equipped with a denser coat of spikes.

In 2017, a team of paleontologists redefined Ankylosaurus once again, revealing its large body size, small teeth, and nostrils that were placed to the side of its head rather than in the front of its snout. Its displaced nostrils might signal an evolutionary change in its diet or sense of smell. But it will take more research—and the discovery of more specimens—to better understand this iconic dinosaur.

Read This Next

The bloody legend of Hungary’s serial killer countess

• Travel

The bloody legend of Hungary’s serial killer countess

Throughout Central Europe, 16th-century noblewoman Elizabeth Báthory is infamous for torture and murder. But was she really as evil as history tells it?

Why scientists want to create psychedelics that give better trips

• Science

Why scientists want to create psychedelics that give better trips

Drugs modeled on natural compounds could help people with anxiety, depression, and addiction. But can side effects, like long-and-winding trips, be eliminated while keeping the therapeutic benefits?

Subscriber Exclusive Content

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

See More

Ankylosaurus: Facts About the Armored Lizard

Live Science is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. Here’s why you can trust us.

Often compared to an army tank or bus, Ankylosaurus was a heavily armored dinosaur with a large club-like protrusion at the end of its tail. Ankylosaurus means "fused lizard" in Greek, and it was given that name because bones in its skull and other parts of its body were fused, making the dinosaur extremely rugged. Ankylosaurus lived in the late Cretaceous Period, about 65.5 million to 66.8 million years ago, and roamed the Western United States and Alberta, Canada.

While this herbivorous dinosaur was a massive animal, a re-examination of its fossils in 2004 by armored dinosaur expert Kenneth Carpenter downsized it a bit. The largest Ankylosaurus specimen ever found was 20. 5 feet (6.25 meters) long, 5.6 feet (1.7 m) tall at the hips and 4.9 feet (1.5 m) wide, according to the study, published in the Canadian Journal of Earth Sciences. It likely weighed up to 4 tons (3.6 metric tons).

The top of the dinosaur was almost completely covered with thick armor consisting of massive knobs and oval plates of bone, known as osteoderms or scutes, which are also common on crocodiles, armadillos and some lizards. "They are bones that form within the skin, just like crocodiles," Carpenter, who's the director of the USU Eastern Prehistoric Museum in Utah, told Live Science.

The osteoderms of all ankylosaurs (dinosaurs in Ankylosaurus' suborder, Ankylosauria) were composed of an thin outer cortical or compact bone and an thick inner cancellous bone (spongy, porous bone), according to an analysis Carpenter and his colleagues published in the journal Acta Palaeontologica Polonica in 2010. The osteoderms were probably covered with skin and keratin, the fibrous protein that makes up hair and nails in people.

The plates, which varied in size, were aligned in regular horizontal rows down the dinosaur's neck, back and hips. There were also smaller plates or other similar features protecting the areas between the larger plates, and there may have also been smaller plates on its tail and limbs. The animal's biggest cluster of armor was in its neck region, Carpenter said.

Along with its armored plating, Ankylosaurus had two rows of spikes along its body. Additionally, its head was long and low, with prominent horns projecting back and to the side and plates protecting its eyes. [Related: Ancient Armored Fish Was Toothy, Too]

Speaking of spikes, a bizarre-looking ankylosaur, described May 10, 2017, in the journal Royal Society Open Science, had such an uncanny resemblance to the spiky-faced "Ghostbusters" monster Zuul that paleontologists named it Zuul crurivastator (CRUR-uh-vass-TATE-or). The species name means "destroyer of shins" in Latin, referring to the ankylosaur's 10-foot-long (3 meters) tail, which was tipped with a club that was likely used to swipe at the legs of predators. The 75-million-year-old remains of this beast were uncovered in 2016 in Montana's Judith River Formation. Despite its ferocious appearance — several rows of bony spikes covered its 20-foot-long (6 m) body — Z. crurivastator was a plant eater, researchers said. 

However, even without these defenses, Ankylosaurus would have been difficult for predators to kill. "You have to understand that they had a very rotund body and were wider than they were deep," Carpenter said. "It would be difficult even without the armor to get a purchase on it because its body is relatively flat."

Aside from its armor, another defining characteristic of Ankylosaurus was its tail club. The tail contained vertebrae that were woven together to form a stiff rod at the base of the club at the end. The stiff tail likely evolved before the knob, according to a 2015 study in the Journal of Anatomy. Scientists have proposed several different hypotheses for the purpose of the dinosaur's club, according to a 2009 study in the journal PLOS ONE. For instance, the tail may have been used for display purposes, such as for attracting mates. Alternatively, it may have been used for combat between two Ankylosaurus, such as over territory or mates. [Related: How Armored Dinosaur Got Its Bone-Bashing Tail]

Whatever the case, it seems the dinosaur did sometimes use its tail as a weapon. "In two fossil specimens, the tail clubs show damage," Carpenter said. "It looks like they definitely struck something hard." What's more, the PLOS ONE study concluded that that the huge tail could easily have broken the bones of most of its predators.

Ankylosaurus moved on all four limbs, and its hind limbs were slightly longer than its forelimbs. Though there are insufficient foot fossils to establish whether Ankylosaurus had toes, it's believed the dinosaurs likely had five toes on each foot like other ankylosaurs.

What did Ankylosaurus eat?

Ankylosaurus grazed on low-lying plants. The dinosaur's triangular skull was wider than it was long and had a narrow beak at the end to aid in stripping leaves from plants. Its small leaf-shaped teeth were not designed to break up large plants and it had no grinding teeth. A broadness to part of its ribcage suggests Ankylosaurus had some sort of fermentation digestive system to break down the massive amounts of un-chewed plants it ate, according to Carpenter's 2004 analysis.

Ankylosaurs had a complex nasal passage and a large cavity volume for the olfactory region of their skulls. The looping nasal cavity probably didn't improve smell much and instead was important for things like regulating temperature, according to a 2011 study in the Journal of Anatomy. However, ankylosaurs seemed to have had a large olfactory bulb (brain structure involved in the sense of smell), so the dinosaurs likely had a strong sense of smell to help seek out food and avoid predators, the study suggested.

Research presented in November 2014 at the annual Society for Vertebrate Paleontology in Berlin further suggests that ankylosaurs' nasal passages helped keep their brains cool.

Fossil finds

A team led by American paleontologist Barnum Brown discovered the first Ankylosaurus fossil — which included the top of a skull, vertebrae, ribs, a shoulder girdle piece and armor — in the Hell Creek Formation of Montana in 1906.

Six years later, Brown unearthed Ankylosaurus osteoderms, which he initially thought belonged to another type of dinosaur. He unearthed his third set of Ankylosaurus remains in Alberta in 1910 when on an expedition at the Scollard Formation — it included ribs, limb bones, armor, a complete skull and the first known tail club. All three of Brown's finds are housed at New York's American Museum of Natural History. In 1947, Charles M. Sternberg discovered the largest known Ankylosaurus skull.

No complete Ankylosaurus skeleton has been unearthed to date. And aside from the isolated bones, armor and teeth, only three major specimens of Ankylosaurus have been unearthed.

"This raises an interesting question: Why is it so rare?" Carpenter said. One possibility, he said, is that the dinosaur lived upland in environments away from the rivers and swamps that are conducive to fossilization. Or, they may not have been all that common in the ecosystem at the time. "We just don't know why they are so rare," he said.

Kim Ann Zimmermann contributed to this article.

Related pages

• A Brief History of Dinosaurs

More dinosaurs:

• Allosaurus: Facts About the 'Different Lizard'
• Apatosaurus: Facts About the 'Deceptive Lizard'
• Archaeopteryx: Facts About the Transitional Fossil
• Brachiosaurus: Facts About the Giraffe-like Dinosaur
• Diplodocus: Facts About the Longest Dinosaur
• Giganotosaurus: Facts About the 'Giant Southern Lizard'
• Pterodactyl, Pteranodon & Other Flying 'Dinosaurs'
• Spinosaurus: The Largest Carnivorous Dinosaur
• Stegosaurus: Bony Plates & Tiny Brain
• Triceratops: Facts About the Three-Horned Dinosaur
• Tyrannosaurus Rex: Facts About T. Rex, King of the Dinosaurs
• Velociraptor: Facts About the 'Speedy Thief'

Time periods

Precambrian: Facts About the Beginning of Time

Paleozoic Era: Facts & Information

• Cambrian Period: Facts & Information
• Silurian Period Facts: Climate, Animals & Plants
• Devonian Period: Climate, Animals & Plants
• Permian Period: Climate, Animals & Plants

Mesozoic Era: Age of the Dinosaurs

• Triassic Period Facts: Climate, Animals & Plants
• Jurassic Period Facts
• Cretaceous Period: Facts About Animals, Plants & Climate

Cenozoic Era: Facts About Climate, Animals & Plants

• Quaternary Period: Climate, Animals & Other Facts

• Pleistocene Epoch: Facts About the Last Ice Age
• Holocene Epoch: The Age of Man

Additional resources

• Dinosaur Provincial Park, in Alberta, Canada, which "contains some of the most important fossil specimens discovered from the 'Age of Dinosaurs' period of Earth's history,"is a UNESCO Heritage Site.
• "Ankylosaurus Fights Back " is an interactive book app from the Smithsonian Institution for children ages 3 to 8. It teaches literacy skills and provides fascinating information on the prehistoric world.
• Read Barnum Brown's original 1908 article, "The Ankylosauridae, a New Family of Armored Dinosaurs From the Upper Cretaceous," in the Bulletin of the American Museum of Natural History.

Joseph Bennington-Castro is a Hawaii-based contributing writer for Live Science and Space.com. He holds a master's degree in science journalism from New York University, and a bachelor's degree in physics from the University of Hawaii. His work covers all areas of science, from the quirky mating behaviors of different animals, to the drug and alcohol habits of ancient cultures, to new advances in solar cell technology. On a more personal note, Joseph has had a near-obsession with video games for as long as he can remember, and is probably playing a game at this very moment.

Ankylosaurus: description, characteristics, photo

A huge dinosaur that lived in the Early Cretaceous period in North America and was called Ankylosaurus, was covered from head to tail with dense, bone armor, consisting of individual plates. Large, triangular, horn-shaped protrusions protected the base of his skull.

Sharp spikes protruded from the skin along the entire body and tail. The tail of the ankylosaurus was massive and ended in a heavy bone knob. Since Ankylosaurus neighbors were such large predators as Tyrannosaurus Rex and Albertosaurus, he had good reason to arm himself so seriously.

Scientists believe that the thickening at the end of the tail was formed from bone nodes, initially covered with skin, which, as they grew, connected and fused with the bones of the tail. At the very beginning of the thickening, the bones of the tail were connected very tightly, so that the end of the tail was very rigid and strong.

The movement of the knob was controlled by special muscles located at the base of the tail and usually used to move the hind limb backward when walking. With the help of these muscles, the animal could move its tail from side to side.

Thick bony plates were, apparently, a very good defense even against large theropods. However, Apkylosaurus' belly was not protected by anything, so when attacked, Ankylosaurus lay down to protect the most vulnerable part of its body. If the predator managed to turn the ankylosaurus on its back, it was deadly, but with the enormous weight of the animal, this was very difficult to do.

Ankylosaur hunting theropods were tall, heavy, bipedal animals. Consequently, they were less stable on their feet than a short, four-legged dinosaur. In addition, the large weight of the predator hid another danger: when attacked, it could break bones, especially the thin bones of the paws. A well-timed and accurate lateral blow from the heavy tail of an ankylosaurus could take a predator by surprise and knock it off its feet, causing serious injury, and sometimes even death.

Ankylosaurus, one of two members of the ankylosaurid family, lived in North America. His relative lived in East Asia. Ankylosaurids first appeared in Asia, this happened at the very beginning of the Early Cretaceous period, when Asia and North America were connected by a strip of land. Apparently, the ancestors of the ankylosaurus crossed this peculiar land bridge from Asia to North America.

It is sometimes described as a living tank, since the entire body of the lizard was encased in extremely strong armor. Ankylosaurus could always try to resist the attack of even the most ferocious and hungry predators.

Despite the fact that a complete skeleton of an ankylosaurus has not yet been found, and that related dinosaurs are better studied, it is an ankylosaurus that is considered to be the most typical (archetype) representative of armored dinosaurs. Moreover, this is one of the most famous dinosaurs, despite such a scarce fossil material.

Other ankylosaurids had similar features: a body covered with powerful, heavy armor, and a massive thickening, a kind of "club", on the tail. However, Ankylosaurus surpasses all its relatives in size and is the largest of all known ankylosaurids.

Ankylosaurus's body was undoubtedly quite massive. In addition, he had strong bone armor that covered the entire upper body and tail. This armor consisted of many small bone plates or plaques ingrown into the skin of the ankylosaurus.

As an additional protection, in the center of each such growth there was a spike-like thickening. The growths were covered with horny scales and soldered (connected) to each other in long strips, which is one of the reasons why this dinosaur is called an ankylosaurus - "soldered lizard".

As you might have guessed, the armor was very heavy. In fact, the ankylosaurus weighed more than two tons - almost half the weight of an African elephant. The body of the ankylosaurus was long - almost the size of a bus.

Soft belly

Hard, sharp spines protruding from the back made the ankylosaurus armor even more impregnable, so that the only part of the body that was not protected from attack by predators was its soft belly. Sometimes the enemy could try to knock the ankylosaurus onto its back, and then attack the lizard in this vulnerable position.

Generally speaking, the prospect of an attack on an ankylosaurus clad in indestructible armor should have deterred predators. Even the most ferocious carnivorous dinosaurs like the Tyrannosaurus rex had to think twice before attacking it.

Armored ankylosaurus could lay down to fight back even a larger predator, inflicting a blow with its tail, at the end of which there was a huge heavy growth. Such a blow could knock over a tyrannosaurus rex moving on two legs. Naturally, the position of the predator in this case was less stable than that of the four-legged ankylosaurus. After such a blow, the predator could hardly get up and was probably doomed to a long and painful death.

Tail Arms

The most spectacular part of Ankylosaurus' huge, massive skeleton is undoubtedly the bulge at the end of its thick, powerful tail. This powerful weapon, used for self-defense, was about five times the width of a human head. It consisted of dense bone outgrowths, fused at one end.

However, Ankylosaurus was a herbivore and never killed for food. With its toothless, beak-like mouth, it plucked leaves from tree branches. The teeth of Ankylosaurus were located deep in the mouth and were very small and weak, but still suitable for chewing soft plant foods.

Ankylosaurus also had a bony partition between its nose and mouth, which allowed it to eat and breathe at the same time. This ability is inherent in humans, but is absent in most modern reptiles.

Skull

The wide skull of an ankylosaurus was covered with bone outgrowths. Four small horns were placed at the four "corners" of the skull. The jaws of the lizard were also protected by bone outgrowths. The head of the ankylosaurus was truly well protected - even its eyelids were bone. The ankylosaurus moved on four legs, which could withstand the enormous weight of the body clad in armor.

Agility

Surprisingly, according to scientists, the ankylosaurus did not have to be slow and clumsy at all. On the contrary, he could move quite quickly due to the large step width.

If an ankylosaurus found itself face to face with a predator unexpectedly and could not escape, it could choose another strategy: bend its legs and burrow its clawed feet deep into the soil to protect its soft belly in case the attacker tried to knock it over on its back .

The numerous bony plates and spikes on the back of the ankylosaurus were not actually part of its skeleton. They grew into the skin, and were not attached to the spine or ribs, so they are not in the figure, which reproduces the structure of the skeleton. Nevertheless, in the structure of the ankylosaurus body, they were the most important part.

Mace Tailed Dinosaur: Bone Crusher

Dinosaur Ankylosaurus probably couldn't have killed a Tyrannosaurus rex with a mace on its tail, but a new study suggests that a bone club could have definitely broken its ankles. To gauge how hard an Ankylosaurus could hit with its tail club, Canadian researchers studied CT scans of several fossilized dinosaur tails of varying sizes.

Combining imaging data with measurements of the dinosaur's spine, they determined that the ankylosaurus could move its tail in a 100-degree lateral arc, and that the large maces could generate force strong enough to crush bone.

"The little ones are like being hit with a bowling ball," said dinosaur researcher Victoria Arbor of the University of Alberta in Canada, author of the study published in PLoS ONE . "And you really wouldn't want to be around when the bigger ones are rocking."

Scientists have long assumed that heavily armored ankylosaurs used their tail clubs to fend off other dinosaurs, but until now no one has studied whether the club was a biologically feasible weapon. Using computed tomography data and 3D computer modeling software, Arbor calculated the volume, mass, and impact velocity of both the small and large tail clubs of ankylosaur dinosaurs.

Researchers believe that the tail club, composed of tightly interlocked vertebrae with a large bony ball at the end, probably had a limited vertical range of motion, but could swing freely from side to side. Arbor concluded that the largest parts can generate an impact force of 364 to 718 megapascals - enough to break a bone.

"Twisting or cutting a bone takes about 100 megapascals to break it," Arbor said. “I have found that over a certain area, the smallest tail clubs cannot break bone, but the largest ones can.”

Because tail clubs are often found separate from the rest of the dinosaur skeleton, it is difficult to tell which had a large tail club and which had a small one. But the researchers believe the smaller tail clubs likely originated from young dinosaurs that had not yet reached sexual maturity.

“Juvenile ankylosaurs don't really have a protrusion at the end of their tail,” Arbor said. “They are born without it, and then as they grow up, their armor slowly develops from head to tail. It is possible that they only develop tail clubs at puberty, or at least when they are very large.”

Since baby dinosaurs were at the greatest risk of predation, it seems strange that only adults had tail clubs that worked as effective weapons. Arbor believes this may indicate another use for the bone ball at the end of the dinosaur's tail. "It's important to remember that structures can often have more than one function," she said. “If you look at modern animals like giraffes, when males fight, they actually hit each other with their necks and heads. I'm wondering if ankylosaurs did the same thing, but if they used their tails instead."

To find out, Arbor hopes to conduct future studies to identify rib fractures in adult ankylosaurs.

Learn more

• 
  Learning letters for kindergarteners
• 
  Kids learning counting
• 
  Calming techniques for toddlers
• 
  List of be verbs in english
• 
  Learn math for kindergarten
• 
  Helping with spelling
• 
  My first day of school story
• 
  Short story kids stories
• 
  Words that a first grader should know
• 
  10 basic shapes
• 
  Skills for first graders