How Pterosaurs Worked


The size of a small airplane, Quetzalcoatlus northropi was one of the largest pterosaurs to fly the Cretaceous skies.
The size of a small airplane, Quetzalcoatlus northropi was one of the largest pterosaurs to fly the Cretaceous skies.
MR1805/iStock/Thinkstock

Imagine hopping into a time machine. You find the time and location knobs preset to "70 million years ago" and "West Texas." Why not, you think. With some hesitation you push the bright red start button and BAM! You're transported to an ancient floodplain dotted with cypress, laurel, mangroves and various cone-bearing trees. Amazingly, it seems to have worked [source: NPS].

Panicked, you check your phone, but to no avail — you're in the late Cretaceous period. As the sobering realization sets in that help is out of reach, you get an uneasy feeling that something's behind you. As you swing around, a massive winged beast the size of a small airplane, 36 feet (11 meters) across, slices through the air just above you at speeds approaching 67 miles per hour (108 kilometers per hour) [source: Castro].

Terrified, you dive to the ground as it lands nearby. A cautious glance reveals a giant reptile with wings unlike any bird or bat you've ever seen. Walking on all fours, the creature picks through the vegetation with a long, toothless beak, and eventually snatches a small animal hiding in the brush. As tall as a giraffe, this monster is Quetzalcoatlus northropi, one of the largest pterosaurs ever to grace the prehistoric skies [source: Witton and Naish].

Named from Greek words meaning "winged lizards," pterosaurs were a group of flying reptiles that first appeared on Earth about 215 million years ago. They were the first vertebrates, or backboned animals, to take to the sky, beating birds and bats by millions of years. Though they're not technically dinosaurs, they lived during roughly the same period and also went extinct when a comet impact threw the planet into chaos some 65 million years ago. By the end of their run, pterosaurs had spread across the globe, inhabiting what's now North and South America, Europe, Asia, Africa and Australia [source: Unwin].

Unfortunately, we don't have time machines to take us back to the time of the pterosaurs, but we do have paleontologists, scientists who study and interpret fossils. They've been able to use old rocks and bones to discover some pretty amazing things about how these creatures evolved, what they looked like and how they flew. Once you get to know pterosaurs, you'll see why some have called them "dragons of the sky."

Pterosaur Types

Pteranodons shaped how pterosaurs are represented in today's popular imagination.
Pteranodons shaped how pterosaurs are represented in today's popular imagination.
Elenarts/iStock/Thinkstock

Most people learn about pterosaurs from the movies, but unfortunately these depictions do little to capture the diversity of these amazing creatures. The one in "King Kong" (1933), for example, was virtually the same as the one portrayed nearly 70 years later in "Jurassic Park III" (2001). In reality, paleontologists have identified roughly 130 pterosaur species, ranging from the airplane-sized Quetzalcoatlus northropi to Nemicolopterus crypticus, which was no bigger than a small songbird [sources: Witton, Wang et al.]. Some had teeth, some had tails, and the head crests came in all different shapes and sizes. The truth, it turns out, is more interesting than fiction.

But before we move on, where did Hollywood get their inspiration? Mostly from Pteranodon, a pterosaur with a wingspan as wide as 22 feet (7 meters), a long, toothless beak, and a bony crest [source: Unwin]. Filmmakers likely latched on to these iconic creatures because they were discovered early and often. Paleontologist O.C. Marsh collected the first fossils in western Kansas in 1870, and since then, more than 1,000 specimens have been dug up, making it one of the best-represented pterosaurs on Earth. Pteranodon was also the first pterosaur discovered in the United States, and there's nothing movie-goers like better than an all-American hero! [sources: Bennett, Unwin]

While Pteranodons are a bit bizarre in their own right, other pterosaurs took things to a whole new level. One way was through those head crests. Take Tapejara imperator, a pterosaur from the late Cretaceous period found in northeast Brazil. Its headgear, which looked like a boat sail fanning outward off the back of its skull, would have been the perfect accessory for the country's Carnival celebration [source: Hone et al.]. Another pterosaur from that period, Nyctosaurus, sported an antlerlike crest three times the length of its skull that made it look like it was wearing a set of television-antenna rabbit ears [source: Bennett].

And then there's Pterodaustro, a pterosaur that originated during the early Cretaceous in Argentina. This creature was much smaller than Pteranodon, with a wingspan just over 4 feet (1.3 meters), and it had a long, upward-curving snout. Embedded in the bottom jaw were more than 1,000 long, needlelike teeth that gave Pterodaustro the appearance of a massive underbite. This peculiar look led one pterosaur researcher to call it "a toothbrush with wings" [source: Hone et al.]

Pterosaur Evidence

A good pterosaur fossil is hard to find because the critters' thin, hollow bones didn't typically hold up well during the fossilization process. The ones that do exist tell a fascinating story of how these ancient reptiles flew.
A good pterosaur fossil is hard to find because the critters' thin, hollow bones didn't typically hold up well during the fossilization process. The ones that do exist tell a fascinating story of how these ancient reptiles flew.
Kevin Schafer/Photolibrary/Getty Images

Until paleontologists can figure out how to bring pterosaurs back to life Jurassic Park-style, they'll have to rely on fossils to explain what these creatures were like. And ever since the first discovery of pterosaur remains in the late 18th century, they've been trying to do just that — with varying degrees of success.

See, good pterosaur remains are relatively rare and often incomplete because their light, hollow bones are fragile and not particularly well-suited for the fossilization process. Even when a good specimen is found, it's easily damaged when extracted, transported and prepared. As a result, pterosaurs have presented a particularly challenging puzzle that paleontologists are still trying to piece together [sources: American Museum of Natural History, "Fossils"].

No one is sure exactly who found the first pterosaur skeleton, but it was dug out of a 150-million-year-old limestone layer in Germany sometime between 1767 and 1784 [source: Switek]. The specimen then made its way to Cosimo Alessandro Collini, an Italian natural scientist who didn't really know what to make of it. He incorrectly concluded that its unusually long fourth finger supported a paddle for swimming, though in his defense, the skeleton was found in an ancient lagoon, surrounded by the fossilized remains of oceanic creatures. It wasn't until 1801 that the French naturalist Georges Cuvier figured out that the specimen, which he later named "pterodactyle," didn't have paddles, but wings. Despite this early attention to pterosaurs, paleontologists soon lost interest in the creatures as fossils proved scarce and were poorly understood [sources: Monastersky, Switek].

By the 1970s, modern theories and techniques brought pterosaurs back into the spotlight. While paleontologists had long suspected that the flying reptiles were fish eaters, new research suggested they were a lot less picky, with diets that also included tiny freshwater invertebrates and even small dinosaurs. Discoveries of nesting sites and fossilized eggs showed that pterosaurs likely congregated in groups and laid soft-sided eggs that they buried for protection. One egg, discovered in 2004, even had an unhatched little pterosaur in it! From that find, paleontologists were able to determine that these creatures were probably able to take care of themselves and even fly shortly after they hatched. Oh, and the head crests? Those may have been unique to males [sources: Switek, Unwin, Than].

Clearly, there's been a lot of exciting research, but stay tuned for more: One paleontologist has declared the 21st century the "golden age of pterosaur research."

Pterosaur Evolution

In the 19th century, scientist Georges Cuvier suggested these giant creatures were reptiles.
In the 19th century, scientist Georges Cuvier suggested these giant creatures were reptiles.
Leemage/Universal Images Group/Getty Images

When naturalists first began studying pterosaur fossils at the turn of the 19th century, they had the same reaction you probably would: What IS that? They didn't really have anything to compare the bones to, and as a result, misguided theories began flying faster than a pterosaur with a tailwind. But this is science. New discoveries soon led to new knowledge, and today paleontologists know much more about pterosaurs' place in evolutionary history.

It's not too surprising that scientists initially tried to connect pterosaurs to modern birds and bats, given their shared ability to fly. Anatomy and surgery professor Samuel Thomas von Sommering first suggested that the creatures were some type of bat in the early 1800s, a theory that was only bolstered by some pretty great drawings of furry pterosaurs with big ears. Paleontologist Harry Seeley made a similar goof in his 1901 book, "Dragons of the Sky," in which he insisted birds were the descendants of pterosaurs [source: Unwin].

While there are a lot of reasons these two men were wrong, the most basic explanation has to do with the wings. On both bats and pterosaurs, the wings are made from a membrane stretched between their arms and legs. However, the outer part of this wing is supported by four fingers in bats and just one finger in pterosaurs. Bird wings are mostly supported by their arms and are obviously covered in feathers [sources: Unwin, Hutchinson].

What's less clear is what came before pterosaurs. Cuvier, the French naturalist, took a step in the right direction when he suggested in the early 1800s that pterosaurs were reptiles (although that theory didn't gain full acceptance for another century). Since then, paleontologists have been working their chisels dull trying to place them on the reptile family tree. The problem is that no one has found a protopterosaur — basically a transition fossil between pterosaurs and their lizardlike ancestors. But that hasn't stopped paleontologists from guessing. Of the four main theories that explain pterosaur ancestry, the one that seems to have gained the most acceptance places them in Ornithodira, sort of a sister group to the dinosaurs [sources: Unwin, Witton].

Pterosaur Flight

For years, researchers doubted pterosaurs' flying abilities, but we now know just how well their strong arms and lightweight wings helped launch them through the sky.
For years, researchers doubted pterosaurs' flying abilities, but we now know just how well their strong arms and lightweight wings helped launch them through the sky.
Mark Garlick/Science Photo Library/Corbis

It's hard to imagine any animal the size of a giraffe getting off the ground and staying airborne for very long. After all, birds and bats are nowhere near that big! But when it comes to pterosaurs, forget what you know about modern fliers. These flying reptiles, which took to the skies some 80 million years before our feathered and fuzzy friends, had their own strategies for launching into the air and soaring above the prehistoric earth [source: Habib]. And, it turns out, they were actually pretty good at it.

As we mentioned before, pterosaur wings consisted of a membrane stretched between the legs, arms and an especially long fourth finger. The wing bones — hollow and as thin as a playing card — were incredibly lightweight and flexible, but also very strong. They supported the skin and muscle membrane, which was reinforced by long fibers that ran from front to back. This system allowed pterosaurs to adjust the tension and shape of their wings for maximum flying ability [source: American Museum of Natural History].

But how did they get off the ground? Like modern bats and birds, pterosaurs didn't just start flapping their wings to get airborne; they had to launch themselves into the air first and then engage the wings. At first, paleontologists figured they must have jumped off their hind legs because that's what birds do. However, further research into pterosaur anatomy revealed that these creatures' arms were actually stronger than their legs – exactly the opposite of birds. This, coupled, with new findings that they were quadrupedal (walked on all fours), suggested that pterosaurs also used all four limbs to catapult themselves into the air. More limbs meant more power, giving even the largest pterosaurs some serious ups [source: Vogel].

This takeoff strategy, despite being more than 200 million years old, has recently gained the attention of the United States Department of Defense. Working with a pterosaur researcher, they're hoping to develop an aircraft system that could allow pilots to make quick vertical launches or take off without a lot of fuel. If they're ever able to make this work, flight will really have gone full-circle: from the first flying vertebrates to the latest aircraft technology [source: Sneed].

Author's Note: How Pterosaurs Worked

Like almost every little boy of my generation, I loved dinosaurs. I liked reading about them, visiting museums about them and wearing them on my T-shirts. My mom said I was basically a walking dinosaur encyclopedia, ready to spout off the length and time period for every species from Tyrannosaurus rex to Brachiosaurus. Imagine my surprise, while researching this article, to find out that pterosaurs weren't actually dinosaurs. I didn't even use the right name, mistakenly calling them "pterodactyls" instead. Little me would have been disappointed but glad to have this opportunity to set the record straight — and have someone besides Mom listening to him go on about prehistoric reptiles.

Related Articles

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