Over the past fifteen years, paleontologists have described more than twenty species of feathered dinosaurs. Even dinosaurs once thought to have dry, scaly skin, such as Velociraptor, have turned out to have feathers. But paleontologists have actually known of at least one feathered dinosaur since the mid-19th century. They just did not know to call it a dinosaur.
In 1861, the German paleontologist Hermann von Meyer described two remarkable fossils preserved in slabs of 150-million-year-old limestone. The first was a single feather—a sure sign that birds have been around for quite a long time—but the second was not as easy to interpret. A partial skeleton surrounded by feathers, the creature seemed to be almost equal parts reptile and bird. Since the skeleton had come from the same type of limestone quarry as the feather, though, von Meyer concluded that both fossils represented the same animal, and he applied the name he had given the feather to the skeleton. Together, these were the first recognized remains of Archaeopteryx lithographica.*
Archaeopteryx immediately became one of the most famous fossil creatures ever discovered. The trouble was that no one could agree on what it was or its relevance to the evolution of other animals. Richard Owen, who purchased the skeleton for what is now London's Natural History Museum, thought that Archaeopteryx was the earliest known bird, whereas his rival Thomas Henry Huxley thought that it was an evolutionary dead end that did not tell naturalists much about how birds actually evolved. Even though many naturalists recognized that Archaeopteryx was important to questions about how birds evolved from reptiles, there was very little agreement about how that change occurred.
It has only been in the past few decades, with the confirmation that birds are just modified dinosaurs, that Archaeopteryx has been placed in its proper evolutionary context. Although now pre-dated by the feathered dinosaur Anchiornis, Archaeopteryx remains one of the oldest feathered dinosaurs known and is still central to questions about bird origins. (Whether it is actually the earliest bird, though, depends on how we define what a bird is, something that has become increasingly difficult as paleontologists have found more dinosaurs with bird-like characteristics.) The several specimens of Archaeopteryx now known are some of the most exquisite and most important fossils ever found, and so it is fitting that this feathered dinosaur gets a little extra attention for its big 150.
Over at Pick & Scalpel, paleontologist Larry Witmer reports that Germany will be issuing a special 10-Euro commemorative coin imprinted with the famous Berlin specimen of Archaeopteryx (which was discovered in 1877). These will be available on August 11th of this year, just a few days before the 150th anniversary of the first written mention of the fossil. Germany's Humbolt Museum will also be opening a new exhibit called "Feathered flight—150 years of Archaeopteryx." For now, that is all that is formally planned to celebrate Archaeopteryx, but Witmer promises that he'll be adding photos to a Facebook Archaeopteryx gallery throughout the year, and I plan on writing a few posts about this famous fossil as we approach the big August anniversary.
*I say "first recognized" because an Archaeopteryx specimen was discovered in 1855 and misidentified as a small pterosaur by von Meyer in 1875. Its true identity was not discovered until John Ostrom reexamined it in 1970.