Laura Erickson's For the Birds

(Recording of a Common Loon)

The current issue of National Wildlife magazine has an article about dinosaurs. Just in case you’re among the millions of people who think dinosaurs are extinct and don’t belong in a magazine about living animals, you might be interested to know that Robert Bakker, of the University of Colorado, presented solid evidence over a decade ago that quite a few dinosaur species are still around. He said in the British journal Nature that dinosaurs were not as reptilian as most experts believed–that in fact they were warm-blooded, and lived far differently from any lizards we know. He wrote, “One group still lives. We call them birds.”

Although the pterosaurs, or flying reptiles, did not follow the same evolutionary line that Bakker discusses, they were the most bird- like animals in the world for much of prehistoric times. They were probably warm-blooded, they had some skull features similar to birds, and their feet were very bird-like. They probably fished with their beak-like mouths, and had throat pouches like pelicans. And they flew like birds. From their skeletons, scientists believe that they had a poor sense of smell but excellent eyesight. They were lightly built, with hollow bones. And they had large brains, so probably had good maneuverability when flying.

But there were great differences between the pterosaurs and birds, too. The wing of a bird is framed by its arm bones–but the wing of a pterosaur was framed on its enlarged finger bones, much like a bat. Some of the pterosaurs had thick fur, too–again, more like mammals than birds.

There were two kinds of pterosaurs–the pterydactyls, which were tailless, and the rhamphorhynchoids, which had long tails. Pteranodon, which is one of the most famous of the pterydactyls, had a turkey-sized body but a huge head–six feet from the tip of its long, toothless beak to the end of its long, bony crest. Nobody is sure why pteranodon had that crest–it may have acted as a rudder, since it didn’t have a tail, or it may have acted as a balance for the long beak. It may even have been a sex characteristic, since some specimens of pteranodon have no crests–they may have been the females. Pteranodon had a 27 foot wingspread–more than twice as long as any modern bird.

Rhamphorhynchus, on the other hand, was only 18 inches long, including its tail. It had sharp teeth along its beak–which worked the same way in fishing as the lamellae along a merganser duck’s bill works today, to hold fast to a slippery fish.

Now, of course, the pterosaurs are gone. The oldest known bird that still exists in North America came on the scene about 65 million years ago, just at the time that the flying reptiles were disppearing– that was Minnesota’s own Common Loon.

(Recording of a Common Loon)

This is Laura Erickson, and this program has been “For the Birds.”