A tank-like herbivore with a deadly club tail

Ankylosaurus Fossils show that it was covered in thick, bony plates arranged in regular horizontal rows, a defence that was useful for this large dinosaur and from which it got its name.

Ankylosaurus means “fused lizard” in Greek; the bony plates were fused to the skull down to the enormous tail club with huge knobs, making it extremely tough. Read on to learn more about these tougher dinosaurs.

A vegetarian tank

While these armored dinosaurs were certainly large (the largest Ankylosaurus specimen ever found was 6.25 meters (20 ft) long and weighed about 3.6 tons), the species was herbivorous, meaning meaty prey could rest (relatively) easily near this plant-eater.

What did Ankylosaurus eat?

Fossils indicate that Ankylosaurs grazed on low-growing vegetation along the ground. The heavily armored dinosaur was equipped with blade-shaped teeth that were perfect for grinding through thick undergrowth, but were not suited for combat with other species. These teeth were behind a beak-like formation in the skull of Ankylosaurs.

A tough challenge for predators

Dr. Hans Sues is a senior research geologist and curator of vertebrate paleontology at the Smithsonian Institution’s National Museum of Natural History in Washington, D.C. He has published extensively on many types of dinosaurs, including a 2020 article on the complete skull of an ankylosaur species in the journal Biological Communications.

“The first line of defense was their outer armor, which consisted of bony plates,” Sues says via email. “In fact, ankylosaurs were so heavily armored that even their upper eyelid was protected by a bony plate. One group of ankylosaurs, Ankylosauridaehad huge clubs of bone at the end of their tails, and they could inflict enormous damage on the legs of an attacking predator with their tail clubs.”

Ankylosaurus’s body was thick and stocky, its hind legs stout. It had a broad, triangular skull. But it was its armor that made all the difference: hard plates covered in bony spines protruded from its limbs, and armored knobs called osteoderms or scales protruded from its back.

Horned projections protruded above each eye and on the sides of the face. Not all ankylosaurids had the same armor pattern, but all had armor to protect them from predators, notably Tyrannosaurus, Tarbosaurus, and Deinonychus.

A surprising variation in diet

And Ankylosaur needed that protection because it spent most of its day eating huge amounts of food, stripping leaves off low-growing plants. “They have small teeth that are similar to modern herbivorous lizards,” Sues says. “A stunning discovery of a near-perfect ankylosaur skeleton from Alberta [British Columbia, Canada] preserved gut contents, confirming that ankylosaurs ate plants.”

Sues shared a surprising discovery, however. “A small ankylosaur recently discovered in northern China apparently went into lakes and even ate small fish,” he said. It’s possible that some species evolved to consume animal matter.

Although the first known remains of Ankylosaurus were discovered by Barnum Brown in 1906 in the Hell Creek Formation of Montana, Sues says ankylosaurid dinosaurs have been found in many places around the world, including Europe, Antarctica, Asia, Australia, and North and South America.

“One of the first dinosaurs ever discovered was actually an ankylosaur, Hylaeosaurus “From southern England, discovered in 1831,” he says.

Ankylosaur could smell prey and predators

Ankylosaurs had a complex nasal system with a large cavity volume for the olfactory region of the brain that controls smell. A 2011 study in the Journal of Anatomy suggested that ankylosaurs may have had a highly developed sense of smell to help them find food and avoid other dinosaurs.

We don’t know if ankylosaurs were social as adults, or if they moved in herds. According to Sues, there’s simply no evidence one way or the other, although he said a group of very young ankylosaurs was discovered in the Gobi Desert.

And while Ankylosaurus’s armor and body type may bring to mind alligators and crocodiles, Sues says they’re not related. “The closest living relatives of dinosaurs are birds,” he adds.

Interestingly, research shows that Ankylosaurus lived in what is now the western United States between 65.5 million and 66 million years ago during the Late Cretaceous Period. This means that ankylosaurs were among the last dinosaurs to roam the Earth.

According to the U.S. Geological Survey (USGS), dinosaurs became extinct about 65 million years ago at the end of the Late Cretaceous. In addition to fossil sites in Montana, Ankylosaurus tracks have also been found in the western U.S. in Arches National Park in Utah and in the Patuxent Formation, where the Little and Big Patuxent Rivers meet in Maryland.

The largest Ankylosaurus skull specimen

The largest known skull of an ankylosaur (designated CMN 880) was discovered in 1947 by American paleontologist Charles Sternberg, along with a jawbone and pieces of armor.

This skull suggests a complete specimen, significantly larger than other ankylosaurs discovered around the world, but is also damaged in some areas. It is difficult to get a complete picture of ankylosaur biology, as a complete skeleton has never been found.

Now that’s interesting

A fascinating 2016 discovery of an ankylosaur in Montana’s Judith River Formation bore a striking (and spiky) resemblance to the mythical monster Zuul from the movie “Ghostbusters.” The paleontologists who made the discovery were so impressed by the resemblance between the found skull and the movie monster that they named the specimen Zuul crossbowwhich means “shin destroyer” in Latin and refers to the Ankylosaurus’ long, club-shaped tail.

Original article: Ankylosaurus: A tank-like herbivore with a deadly club tail

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