Natural History: Origin of Baleen

Baleen whales (Mysticeti) are named for the comb-like keratinous plates they use to filter krill and other small animals from the water. How baleen evolved has been a point of controversy. Two main theories have emerged: either the ancestors of baleen whales were toothless suction-feeders, or they were toothed whales that used their teeth to similarly sift small animals from the water. Read more…

Close-up of Coronodon havensteini’s lower premolars and molars; the genus name means “crown tooth.” The overlapping teeth and accessory cusps are interpreted as having been used for filter feeding.
Jonathan Geisler