AN EARLY CRETACEOUS BIRD FROM SPAIN AND ITS IMPLICATIONS FOR THE EVOLUTION OF AVIAN FLIGHT

AVIAN flight is one of the most remarkable achievements of vertebrate evolution, yet there is little evidence of its early phases. Specimens of Archaeopteryx shed important (albeit controversial) light on this evolutionary phenomenon, but large morphological (and almost certainly functional) gap between Archaeopteryx and modern avians remain virtua lly empty until recently. Here we report a new, exquisitely preserved, bird from the Lower Cretaceous Konservat-Lagerstatte of Las Hoyas (Cu enca, Spain) which provides evidence for the oldest known alula (basta rd wing). Crustacean remains found inside its belly also provide the o ldest direct evidence of feeding habits in birds. The new specimen has numerous synapomorphies with the Enantiornithes, but its unique stern al morphology, along with other autopomorphies in the furcula and vert ebral centra, support the recognition of a new enantiornithine taxon, Eoalulavis hoyasi. The combination in Eoalulavis of a decisive aerodyn amic feature, such as the alula, with the basic structures of the mode rn flight apparatus indicates that as early as 115 million years ago, birds had evolved a sophisticated structural system that enabled them to fly at low speeds and to attain high manoeuvrability.