[[Image:archaeopteryxArchaeopteryx1.pngjpg|thumbnail300px|thumb|right|0px|Bird''Archaeopteryx siemensii'', the Berlin specimen found in 1877 near Eichstätt, or dinosaur?Germany; currently displayed at the Humbolt Museum für Naturkunde]]
'''Archaeopteryx''' is a theoretical [[bird]] based on a few [[fossil]] fragments. This theoretical bird is sometimes presented as evidence of evolution because the bones have some characteristics reminiscent of [[reptile]]s, making it appear to be a so-called "transitional" form between reptiles and birds.