Feather a dromaeosaurid found in the Yixian formation (124.6 MYA). Previously, a temporal paradox existed in the evolution of feathers—theropods with highly derived bird-like characteristics occurred at a later time than "Archaeopteryx"—suggesting that the descendants of birds arose before the ancestor. However, the discovery of "Anchiornis huxleyi" in the Late Jurassic Tiaojishan Formation (160 MYA) in western Liaoning in 2009 resolved this paradox. By predating "Archaeopteryx", "Anchiornis" proves the existence of a modernly feathered theropod ancestor, providing insight into the dinosaur-bird transition. The specimen shows distribution of large pennaceous feathers on the forelimbs and tail, implying that pennaceous feathers spread to
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