摘要：A skull of a new pelecaniform bird is described from the Middle Eocene of Messel (Germany). Masillastega rectirostris gen. et sp. nov. is tentatively referred to the Sulidae (boobies and gannets). If this assignment is correct, the new taxon would represent the earliest fossil record of the family, preceding Sula ronzoni Milne-Edwards, 1867 from the lowermost Oligocene of France by about 15 million years. Masillastega rectirostris most distinctly differs from extant Sulidae in the proportionally longer beak which indicates that the Eocene taxon was not adapted to plunge-diving. Contrary to extant Sulidae, which are exclusively marine birds, Masillastega rectirostris was found in a freshwater deposit. It is the first pelecaniform bird known from Messel and one of the few large birds discovered at this site.
