Ornithurae Ornithurae Ornithurae (meaning "bird tails" in Greek) is a natural group which includes the common ancestor of "Ichthyornis", "Hesperornis", and all modern birds as well as all other descendants of that common ancestor. Ernst Haeckel coined the name in 1866 and included in the group all "true birds" with the "characteristic tail morphology of all extant birds" (translation by Jacques Gauthier). This distinguishes the group from "Archaeopteryx", which Haeckel placed in another new group called Sauriurae. Said simply, modern birds have short, fused pygostyle tails, while "Archaeopteryx" retained the long tail characteristic of non-avian theropod dinosaurs. Gauthier converted Ornithurae into
Specimens of Archaeopteryx ähnlichen Federn bedeckten "" ("skeleton of an animal covered in similar feathers"). In German, this ambiguity is resolved by the term "Schwinge" which does not necessarily mean a wing used for flying. "Urschwinge" was the favored translation of "Archaeopteryx" among German scholars in the late 19th century. In English, "ancient pinion" offers a rough approximation. Hermann von Meyer learned of the discovery of what would later be known as the London Specimen before he published his analysis of the single "Archaeopteryx" feather. In September 1861 he wrote to the "Neues Jahrbuch" about being informed of the discovery by Friedrich Ernst