First dolphin species, genus and family to become extinct in modern times

The first (and only) dolphin species to have become extinct in modern times is the baiji or Chinese river dolphin Lipotes vexillifer. Formerly native to China's Yangtze River, it was officially declared extinct in December 2006, since when no confirmed sightings have been documented. Moreover, as it was the only member of the genus Lipotes, this means that Lipotes is the only dolphin genus to have become extinct in modern times. And because it was also the only member of the family Lipotidae, this means that Lipotidae is the only taxonomic family of dolphins to have become extinct in modern times. In 2007, a video was filmed of what may have been a living baiji, but the creature's identity was not confirmed. In any case, if only a single individual remains alive the species is deemed to be functionally extinct, because it cannot reproduce.