Talk about a prehistoric animal with an identity crisis! Was Archaeopteryx lithographica a feathered dinosaur, an ancestor of birds, neither, or both?
Palaeontologists have been puzzling over the answer since 1861, when Archaeopteryx lithographica was first described. Part of the uncertainty arises because the preserved feathers of Archaeopteryx are similar to those of birds, but the skeleton closely resembles that of a small carnivorous dinosaur.
In the 1990s, five kinds of theropod dinosaurs were found in China with a primitive type of feather. This amounted to new information that strongly supports the hypothesis that birds originated from small theropods (the bipedal, "beast-footed" dinosaurs).
Consequently, palaeontologists reserve a special designation for Archaeopteryx: as a transitional link between dinosaurs and birds. In other words, it is considered to be both a feathered dinosaur and an ancient primitive bird.
Archaeopteryx means "ancient wing". The species name lithographica is named after the famous 150 million-year-old Upper Jurassic Solnhofen Limestone quarries of Bavaria in southern Germany in which it was first found. The limestones were formed at the bottom of an ancient moderately deep sea. Lithographic limestone is a smooth stone used in some printing processes. A. lithographica is known from seven specimens plus a feather. A second, geologically younger species, A. bavarica, was discovered nearby and described in the early 1990s.
Archaeopteryx was about the size of a crow with a wingspan of about 60 cm (2 ft.). Its brain was relatively large for an animal of that time.
No bird fossils older than 65 million years were known when the first Archaeopteryx specimens were uncovered. Since then, and especially since the early 1980s, many other Mesozoic fossil birds have been found in localities throughout the world. More than a dozen fossil bird species had been found in China, alone, by 2000.