WITH the description of further specimens1,2 there has been a resurgence of interest in Archaeopteryx. Although there is no final agreement on whether it was mainly arboreal or terrestrial, recent opinion3 seems to favour the latter. There has been discussion on its reptile origins4–6 and on its ability to fly and the general problem of the evolution of powered flight3,7–12. However, most of these studies have been made by specialists who are not ornithologists and who usually tend to extrapolate from reptile forms and behaviour in their discussions. Whatever its precursors, Archaeopteryx is regarded as a bird and to interpret adequately such evidence as we have we must consider it in relation to what we know of birds as well as reptiles.