The Diomedeoididae are a prehistoric family of seabirds. The family was in the order Procellariiformes which today is composed of the albatrosses and petrels. At present the family contains a single genus, Diomedeoides, in which there are three described species. The taxonomy of the family and genus is still in need to revision, and it is likely that the genus name Diomedeoides is actually the junior synonym to Rupelornis (van Beneden, 1871).