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Pterosaurs - Flying Lizards
Flight by animals with vertebrates (backbones) extends back more than 200 million years. Today it is believed that some dinosaurs did fly. They were known as Pterosaurs (flying lizards). Were the Pterosaurs warm or cold blooded? Did they glide and fly? Did they fly fast or slow? Did they have the same body and wing build as a modern bird or bat? We will study all of these questions.
The Many Varieties
The Pterosaurs existed in a variety of shapes and sizes. Their fossils (bones) have been found in many different environments. The Pterosaurs are found in many different sizes. Some were as small as a sparrow is today and others were as big as a DC-3 airplane! Most were the size of a chicken or raven.
Pterosaurs had long snouts (noses) like tweezers. They were able to reach into holes in the ground or between rocks to find food. Others had strainer like teeth which could sieve the food from water in swamps and marshes like the flamingos of today.
Another Pterosaur was the Rhamphorrhynchus. It had a tapered, pointed snout with sharp needle like teeth. Some think this snout was used to catch fish by spearing them while flying low over the water!
Another Pterosaur was the Dimorphodon. It is believed to be a wonderful hunter in the air. It had a massive (large) jaw with sharp opposing teeth. It had a long "S" shaped neck that could snap quickly down to clamp on to its prey.
Clearly, the Pterosaurs had adapted to many different environments, just as birds and bats have today.
The Long and Short of It
Pterosaurs were around so long (165 million years) that they evolved (changed). The early Pterosaurs were bigger than the later ones. The early ones tended to be larger. They had long tails and some had a "kite" like structure at the end of their tail. This kite like tail may have helped balance the creature in flight. The later Pterosaurs were usually smaller and had short tails. The short tail Pterosaurs had broader and more powerful wings.
Gliders or Flyers?
Both the early Pterosaurs and the later Pterosaurs had something in common. They flew very well for millions of years. They seem to have many things in common with modern birds and bats. But, did the Pterosaurs mostly glide, or did they really fly? If you compare a flying squirrel to Pterosaurs or to modern birds you will see many differences. The flying squirrel can only glide down from a high place. It has no wings to flap. It only has a loose flap of skin that stretches from its front legs to its hind legs. The fossils of Pterosaurs show that they had light bones and strong muscles like modern birds and bats. This helps us guess that they were able to fly just as birds and bats do now.
But, having the ability to fly does not mean that one lacks the ability to glide. The modern albatross is an excellent glider, but is able to fly too. It is believed that Pterosaurs living near water or on cliffs were able to glide and fly. For the larger birds gliding helps save energy so they can stay in the air longer. It may have been the same for Pterosaurs. It seems, then, that Pterosaurs could glide and fly.
The Shape of the Wing
The shape of the wing of Pterosaurs is very similar to that of both bats and birds. Both the bat's wing and birds's wing provide lift and are very efficient for powered flight. Pterosaurs had membrane type wings similar to bats, but longer and narrower, similar to birds. This leads us to think that Pterosaurs had precise (exact) flight control as in modern birds and bats.
Like modern birds, Pterosaurs had the bone structure, breast bone and back which allowed for powerful flight muscles. The head and neck were long and seems to have been able to move as needed to catch prey. It is thought that the Pterosaur was quite able to get around on the ground. It had two hind legs and two claws that could be put on the ground when the wings were folded.
Most of the Pterosaur bones appear to be hollow. There was no marrow, but evidence of air sacs as in modern birds. The Pterosaur bones were very light, even lighter than the same size bird.
Were Pterosaurs warm blooded? The type of energy necessary to sustain flight for both active flyers and soarers is substantial (a lot). For sustained (continued) muscle power and powered flight a creature defined as warm blooded seems to be a necessity. That is, the ability to regulate (control) body heat efficiently (well). Since there are no modern cold blooded fliers it is reasonable to guess that Pterosaurs were warm blooded.
Feathers or fur control heat in birds and bats. Pterosaurs seem to have had scales similar to feathers, but not quite feathers. These scales were on the body, not on the wings. The wings were a bare membrane type structure like on a bat.
What about speed? Birds have developed wings which allow them to be very slow to very fast. The larger birds are somewhat slower, but can glide for long periods of time. Smaller birds are faster, such as the swift that can exceed 100 mph. The hummingbird can hover (and some bats too!).
Fossil evidence shows that some Pterosaurs were small and probably fast. Others were larger and probably slow gliders. Pterosaurs seem to have the same speed range as modern birds.
It appears, then, that the Pterosaurs were warm blooded, with the same body structure as birds. This made it possible for them to be able to fly and glide the same as modern birds and bats.
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