Saturday, August 17, 2013

What is a Pterosaur?

Most of you have probably heard about the so-called "pterodactyls," the flying creatures that lived during the time of the dinosaurs. Like most of us, you might not know exactly what a pterodactyl, more properly known as a pterosaur, is. Is it a bird? A bat? A dinosaur? Possibly even an insect? Or a distinct group of archosaurs that are thought to be fairly closely related to both dinosaurs and crocodilians, but scientists still aren't 100% positive how they fit into the reptilian family tree? Well, if you were thinking the last option, then lo and behold: you're right! Although the pterodactyls would have soared through the skies much like birds, bats, and even some insects of today, they would have been a distinct group altogether. They are also not quite dinosaurs: as the last option says, no one knows quite yet how exactly they fit in!
Pyg perches next to the skeleton of one of the most famous pterosaurs, Pteranodon, at the Morrison Natural History Museum in Colorado!  
Another misconception you might be suffering under is what these extinct flying reptiles are actually called. Although most people call them pterodactyls, that isn't quite the correct term for them. Scientifically, these creatures are known as the pterosaurs. The name pterodactyls actually originates from a small pterosaur that is commonly found in the fine-grained Solnhofen fossil beds in Germany. Known as Pterodactylus, several hundred of these little reptiles have been discovered!
Pyg checks out a cast of one of the more famous Pterodactylus specimens from Solnhofen!
The Solnhofen quarries are world renknowed for their excellent fossils. Not only have a large number of Pterodactylus specimens been uncovered there, but it was from these quarries that the very first Archaeopteryx was uncovered in 1861.  This primitive bird is one of the missing links between birds and dinosaurs, as it shares many features in common with both groups (such as feathers with birds and hand claws and teeth with dinosaurs). Other famous and important animals to come out of the Solnhofen Quarries include numerous crustaceans, insects, and even a small crocodile called Alligatorellus!
Pyg learns more about both the Pterodactylus specimen from above (left), but also about Archaeopteryx (right)!  This cast is of the best specimen of this primitive bird, and was discovered in 1877!  (The original specimen was, not the cast).
Part of the reason why the Solnhofen Quarry is so darn special is the extremely fine-detail preserved in the fossils. As I just mentioned in the previous paragraph, feathers have been discovered with Archaeopteryx specimens. Feathers, much like skin, hair, and other soft-tissues, rarely fossilize. As the science of paleontology slowly evolves, just like the animals it studies, paleontologists become better and better equipped to deal with, not to mention find, these soft-tissue elements of these extinct animals. More and more dinosaurs are being discovered with not only skin, but oftentimes feathers, such as Microraptor, an animal fairly closely related to Velociraptor of Jurassic Park fame; Dilong, an ancient ancestor of Tyrannosaurus rex; and the bizarre therizinosaurs; amongst many others.

And it's not just feathers that fossilize, either. Wing membranes, composed of a flap of skin, are being discovered more and more frequently when it comes to pterosaurs. When it comes to Pterodactylus, scientists have such a large sample size that they are able to reconstruct much of the soft-tissue anatomy of this particular pterosaur! Scientists also have a very thorough growth series for this particular pterosaur, with individuals ranging from hatchlings, just a few days to a few weeks old, all the way to very old individuals with wingspans of around five feet, which, for a Pterodactylus, is very hefty indeed!

Although we've talked a lot about Pterodactylus, there are many other fascinating pterosaurs! I've taken a recent interest in pterosaurs, but before we dive on in to a wide variety of posts, I wanted to provide a brief introduction! Remember, this is a VERY brief introduction. For a more thorough introduction to pterosaurs, consult a book or something, or check back in the future as we learn more about pterosaurs! Don't hold me to it, but I feel like sometime in the near future, I will be talking about Dimorphodon and the anurognathids! Check back soon!

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