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Everybody knows Tyrannosaurus rex. And no wonder—the ferocious predator was nearly as tall as a giraffe and heavier than an elephant. It had a mouth full of knives the size of bananas. And when it was hungry, T. rex would have been nothing short of death incarnate.
But what about the dinosaurs that would have gone toe to toe with the bipedal hellhound? Triceratops is often portrayed as a hapless victim cowering beneath the business end of a tyrannosaur. But the fossil record tells us these leaf eaters were no pushovers. Triceratops were longer than Sherman tanks and nearly as impenetrable. They had face shields like beach umbrellas built out of bone, and hulking forehead spikes as big as a toddler. These were animals three times the size of a rhino and with twice the weaponry.
“The exhibition is a fascinating look at the evolution of armor in animals over the course of nearly 600 million years.” – Matt Lamanna, Lead paleontologist at Carnegie Museum of Natural History
The fact of it is, for all the flashy teeth, claws, and other offensive weapons unearthed from the strata, there are just as many examples of brilliant, bone-crushing defensive structures. Dinosaur Armor, a new exhibition created by Carnegie Museum of Natural History in partnership with Gaston Design of Colorado, celebrates all the immovable objects that evolved to protect animals against unstoppable forces such as T. rex.
“The exhibition is a fascinating look at the evolution of armor in animals over the course of nearly 600 million years,” says Matt Lamanna, head paleontologist and dinosaur researcher at Carnegie Museum of Natural History. “Everything from armored invertebrates, like the model of a giant sea scorpion, to armored fishes from before dinosaurs to the influence of natural armor on humanity.”
And of course dinosaurs. The immersive environment includes an array of savage-looking horned dinosaur skulls and terrifying predators such as Utahraptor (a comparatively giant cousin of the famous Velociraptor) and Teratophoneus, whose name translates to “monstrous murderer.”
But perhaps most alluring, Dinosaur Armor boasts three different species of ankylosaurs, or armored dinosaurs, that are unlike anything in the museum’s collection—a collection known for its dinosaurs.
Destroyer of Shins
Ankylosaurus might not be as much of a household name as Tyrannosaurus and Triceratops, but when it comes to animals that have evolved defensive structures, it’s the cream of the Cretaceous.
Ankylosaurs were a group of four-legged plant eaters, says Victoria Arbour, curator of paleontology at the Royal BC Museum in Canada and an expert on these armored animals. They had tiny teeth and a beak like a tortoise, but they were anything but harmless.
“Probably one of the most characteristic things about ankylosaurs is the fact that they’re covered in armor made of bones that grow in the skin, known as osteoderms,” says Arbour.
On the animals’ heads, the osteoderms taper off into horns and other protrusions, while on the top and sides of the body, they assemble into interlocking scutes, similar to medieval chain mail. One group of ankylosaurs, called nodosaurs, is known for sporting spiky shoulder pads. What’s more, all of these adornments would have had “a keratin sheath over top of them that probably made them longer and sharper than just bone alone,” notes Arbour.
But arguably the most distinctive feature found in ankylosaurs is the tail.
“Some ankylosaurs have this very unusual, weaponized tail with a big lump of bone at the end,” Arbour explains. The back half of the tail “is actually really weird when compared to other dinosaurs,” she says, because the vertebrae sort of lock together in a series of nested V’s. “And that makes the back half of the tail completely stiff, kind of like having a sledgehammer at the end of your body.”
In 2017, when Arbour discovered a new species of ankylosaur buried in rock in northern Montana, she named the creature Zuul crurivastator. The first part of the name is an homage to the gatekeeper monster in Ghostbusters, and the second half means “destroyer of shins.”
Play It Again, Evolution
Are you ready for the really wild part?
Roughly 20 million years ago, long past the extinction of non-bird dinosaurs, an animal evolved that looked very much like an ankylosaur. Only this creature had body hair and produced milk for its young, just like us.
“So, there was a group of mammals related to armadillos called glyptodonts,” says Lamanna. “And glyptodonts had extraordinarily ankylosaur-like body plans.”
Bony body armor? Check. Armored heads covered in thick, keratinized skin? Check. Tails that could cave in the side of an SUV? Double check, because some glyptodont species not only had clubs at the end of their tails, but clubs that were covered in keratinous spikes, like a medieval morning star.
This is fascinating because, as mammals, glyptodonts did not descend from ankylosaurs. And yet they evolved many of the same characteristics.
“It’s like life tried to play the ankylosaur song again,” says Lamanna.
These sorts of coincidences occur through a process known as convergent evolution. In short, “if two unrelated species play the same role in their environments, they often independently evolve similar features,” he says.
Ankylosaurs had to survive alongside dinosaur predators such as Tyrannosaurus, Teratophoneus, and Utahraptor. Interestingly, for glyptodonts, the largest predators of the day would have been distant descendants of meat-eating dinosaurs known as phorusrhacids, a now-extinct group of 10-foot-tall “terror birds.” But scientists have also found a glyptodont skull with a set of distinctive puncture wounds that were most likely inflicted by the saber-toothed cat more officially known as Smilodon.
Deliciously, Dinosaur Armor also pays tribute to these interactions with several mounts that re-create the life and death struggles that took place between ancient predators and their armored prey.
“Anytime you get to see a saber-toothed cat attacking a giant ankylosaur-like mammal, I think that’ll be something for people to enjoy,” says Lamanna.
Of course, armor existed long before either mammals or dinosaurs. About 370 million years ago, there was a fortress of a fish known as Dunkleosteus. Fossilized remains, some of which have been found in northwestern Pennsylvania, tell us some members of this genus would have been up to 30 feet long, or roughly the size of the largest killer whales. The head of Dunkleosteus was encased in large, thick plates of bony armor so sturdy that they’re usually the only pieces of the animal paleontologists find.
More commonly known as sea scorpions (but not closely related to today’s scorpions), eurypterids scuttled across coastal sea- and riverbeds from roughly 470 to 252 million years ago. One of the largest known eurypterids created the giant trackway on display in the museum’s Benedum Hall of Geology and is estimated to be 6.5 feet long and 33 inches wide. Like their modern relatives, such as horseshoe crabs, centipedes, insects, spiders, and crustaceans, these critters had a hard outer shell that was segmented into a head, a thorax, and an abdomen.
The Perfect Defense
While the defensive value of armor might seem self-evident, there’s quite a bit of debate about the primary uses of some of these structures. Big, showy frills like those seen in ceratopsids, or horn-faced dinosaurs, might have been more useful for courtship or shows of dominance.
“If you think of things like deer or bighorn sheep, they can use their antlers or horns as defensive weapons, but they’re mostly using them to fight each other,” says Arbour.
The logic follows that ankylosaurs’ tails might have been most useful not against tyrannosaurs, says Arbour, but against other ankylosaurs.
This leads to another mystery. About 75 million years ago, a group of juvenile ankylosaurs were killed and preserved by either a sandstorm or the collapse of a sand dune in what’s now Mongolia. Curiously, while the animals are exquisitely preserved, they’re almost completely devoid of the armor that characterizes their species as adults. This suggests that only adult ankylosaurs had heavy armor.
“How were they defending themselves?” wonders Arbour.
The fact that the young ones are in a group suggests they might have utilized the same safety-in-numbers strategy employed by modern herding animals. Other dinosaurs have been shown to perform some parental care, says Arbour, so that’s possible, too.
From 530-million-year-old trilobites to modern-day pangolins and thorny devil lizards, armor has popped up again and again in the history of life. Shields, shells, and protective coatings are so popular, sometimes animals that can’t create them will steal them from those that can.
Hermit crabs repurpose old snail shells, carrier crabs adorn their carapaces with spiny sea urchins, and octopuses have even been seen carrying around coconut shells that can be used as portable, hard-coated hiding places.
Humans have also gotten in on the armor-stealing game. The Dinosaur Armor exhibition includes a replica of a 3rd-century suit of armor discovered in Egypt that’s made out of crocodile scutes and skin. Another example: a puffer fish turned into a ceremonial headdress.
“It shows how humans have taken inspiration from nature when it comes to protecting our own bodies,” says Lamanna.
Scientists are still looking to animals for ways to improve armor and other hard-to-destroy materials. Engineers have studied ironclad beetles, which can survive being run over by a car, to help develop military vehicles that can better withstand explosions. And the scales and osteoderms of crocodiles, armadillos, and fishes have informed researchers working on a new form of armor made from flexible glass.
Ankylosaurus and Dunkleosteus would be proud.
Dinosaur Armor is supported by PA Virtual Charter School and sponsored by Baierl Subaru.
Drawn To Nature
A scientific illustrator’s path to re-creating life in Earth’s deep past.
Andrew McAfee regularly travels deep into the past to imagine Earth as it was tens or even hundreds of millions of years ago, when the oceans and forests and deserts teemed with strange creatures. The scientific illustrator mostly brings to life dinosaurs, partnering with Carnegie Museum of Natural History’s lead paleontologist, Matt Lamanna. But for Dinosaur Armor, a new exhibition all about the evolution of extreme body structures, McAfee puts museumgoers face-to-fish with the giant extinct sea monster Dunkleosteus.
The 10-foot-tall mural is one of four that helps immerse visitors in an experience that spans nearly 600 million years. So, what’s it like to create art that puts a face to a name for such mysterious animals? McAfee thinks out loud about the challenge medical illustrators faced when creating the iconic, spiked coronavirus image. “We think of the coronavirus as being red, an angry, dangerous color, because that’s how it was reproduced,” says McAfee. “The virus is probably colorless,” he adds, and he’s mostly right. The well-known image created by the Centers for Disease Control and Prevention is scrupulously faithful to what is known about the virus’s structure, scientists say, but the red-and-gray color scheme is all artistic license, a nod to the seriousness of the pandemic. “My point is, we’re all influenced by art,” says McAfee. “It matters.”
McAfee grew up catching frogs, hunting for snakes, and drawing comics. Interested in both science and art, he opted to study biology in college. But when the Peace Corps took him to Guatemala for two years after graduation, he started drawing the people and animals he came across as much to pass the time during the rainy season as to document his experience.
“I didn’t realize it then, but I was building a portfolio that would lead me to grad school,” says McAfee. “But even then, I didn’t know scientific illustration was a career path.”
A career that helps make complex science understandable. For instance, before he can get to the point of creating what he calls a soft-body reconstruction of an animal—a depiction of it as it lived in its body and in its environment, like the massive Dunkleosteus—his work often starts with a single fossil, and in the case of Dunkleosteus, it was the head. After illustrating individual fossils, with guidance from the collaborating scientists, he moves to the skeleton. “We figure out the skeleton, then we take the skeleton and figure out the body. The project builds from material we have to the paleontologist’s interpretation.”
Speaking of interpretation, McAfee says he added a few “surprise animals” in the environments he created for Dinosaur Armor. Be on the lookout for a prehistoric bird, dragonflies, and maybe even a bizarre-looking relative of the armadillo known as a glyptodont.
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