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
Archaeopteryx be given preference over "lithographica" in instances where scientists considered them to represent the same species. It has been noted that the feather, the first specimen of "Archaeopteryx" described, does not correspond well with the flight-related feathers of "Archaeopteryx". It certainly is a flight feather of a contemporary species, but its size and proportions indicate that it may belong to another, smaller species of feathered theropod, of which only this feather is known so far. As the feather had been designated the type specimen, the name "Archaeopteryx" should then no longer be applied to the skeletons, thus creating significant nomenclatorial