Pteranodon Icon

The pteranodon is the best known of the many flying reptiles which filled the skies during the age of dinosaurs. Pteranodon had an immense wingspan.

We do not know how pteranodon and the other large featherless, flying reptiles were able able to take off and land, or even how they remained aloft. Perhaps they remained aloft for their entire life. Their lives are a mystery.

But we do know that from that from its aerial location, pteranodon had an unsurpassed view. The view and the mystery make petranodon a perfect icon for this project.

Paleontologist Adrian Desmond discussed pteranodon in his book The Hot Blooded Dinosaurs:

Pteranodon had lost its teeth, tail and some flight musculature, and its rear legs had become spindly. It was, however, in the actual bones that the greatest reduction of weight was achieved. The wing bones, backbone and hind limbs were tubular, like the supporting struts of an aircraft, which allows for strength yet cuts down on weight. In Pteranodon these bones, although up to an inch in diameter, were no more than cylindrical air spaces bounded by an outer bony casing no thicker than a piece of card. Barnum Brown of the American Museum reported an armbone fragment of an unknown species of pterosaur from the Upper Cretaceous of Texas in which "the culmination of the pterosaur... the acme of light construction" was achieved. Here, the trend had continued so far that the bone wall of the cylinder was an unbelievable one-fiftieth of an inch thick Inside the tubes bony crosswise struts no thicker than pins helped to strengthen the structure, another innovation in aircraft design anticipated by the Mesozoic pterosaurs.
 
The combination of great size and negligible weight must necessarily have resulted in some fragility. It is easy to imagine that the paper-thin tubular bones supporting the gigantic wings would have made landing dangerous. How could the creature have alighted without shattering all of its bones How could it have taken off in the first place It was obviously unable to flap twelve-foot wings strung between straw-thin tubes. Many larger birds have to achieve a certain speed by running and flapping before they can take off and others have to produce a wing beat speed approaching hovering in order to rise. To achieve hovering with a twenty-three foot wingspread, Pteranodon would have required 220 lb. of flight muscles as efficient as those in humming birds. But it had reduced its musculature to about 8 lb., so it is inconceivable that Pteranodon could have taken off actively.
 
Pteranodon, then, was not a flapping creature, it had neither the muscles nor the resistance to the resulting stress. Its long, thin albatross-like wings betray it as a glider, the most advanced glider the animal kingdom has produced. With a weight of only 40 lb. the wing loading was only I lb. per square foot. This gave it a slower sinking speed than even a man-made glider, where the wings have to sustain a weight of at least 4 lb. per square foot. The ratio of wing area to total weight in Pteranodon is only surpassed in some of the insects. Pteranodon was constructed as a glider, with the breastbone, shoulder girdle and backbone welded into a box-like rigid fuselage, able to absorb the strain from the giant wings. The low weight combined with an enormous wing span meant that Pteranodon could glide at ultra-low speeds without fear of stalling. Cherrie Bramwell of Reading University has calculated that it could remain aloft at only 15 m.p.h. So takeoff would have been relatively easy. All Pteranodon needed was a breeze of 15 m.p.h. when it would face the wind, stretch its wings and be lifted into the air like a piece of paper. No effort at all would have been required. Again, if it was forced to land on the sea, it had only to extend its wings to catch the wind in order to raise itself gently out of the water. It seems strange that an animal that had gone to such great lengths to reduce its weight to a minimum should have evolved an elongated bony crest on its skull.

Desmond wrote his book in the 1970's. His suggestion that pteranodon was unable to flap its wings dates from an era when most paleontologists believed that pterosaurs were poorly adapted for active flight and mainly used gliding and the wind to fly. But more recent analyses of pterosaur skeletal features suggests that all but the largest pterosaurs could sustain powered flight. Pterosaurs had hollow bones, large brains with well-developed optic lobes, and crests on their bones to attach flight muscles.

This view of pteranodon as a flyer capable of flapping flight is also supported by fossil bones of giant terotorn birds discovered in Argentina during the 1970s. The terotorn was a 160 to 200 lb eagle with a 27' wingspan. Its design is similar to a modern bird and thus is capable of flapping its wings, and making aerial maneuvers. It can be argued that at least some some limited flying ability is necessary for any aerial creature. If pteranodoan had lived totally as a glider, the first contrary wind would carry it away from its nest.

For more information on current thinking on how pteranodon and other pterosaurs flew, jump to the pterosaurian flight portion of a University of California series of pages on the wonder of flight in vertebrates. This site also has further information on pteranodon.

Desmond suggests that pteranodon had a lifestyle similar to a pelican. It soared over the waves and snapping up fish without landing. Desmond notes that pteranodon had a throat pouch like a pelican, and has been found with fish fossils. The figate bird has a similar aerial life.

The pteranodon's way of life was impervious to practically all mishap, as it stayed aloft over floods and other catastrophes of a many millions of years. Hopefully, this project will soar as successfully.

Desmond wrote his book in the 1970's, shortly after paleontologists had found partial remains of even larger pterosaurs that may have lived as carrion eaters far from the water. The largest vertebrate ever known to fly, the late Cretaceous Quetzalcoatlus, may have had a carrion eating lifestyle. But, I prefer pteranodon's lifestyle. Big is big, but biggest isn't necessarily best.

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