Extinct and Living Baleen Whales (IMAGE)

University of California - Riverside

Extinct and Living Baleen Whales

Caption

Extinct baleen whales, such as Aetiocetus weltoni (top; ~25 million years old) possessed teeth with enamel. Living baleen whales (bottom) lack teeth and feed on minute organisms with their brush-like baleen filters. Despite the absence of teeth, modern baleen whales retain copies of tooth-specific genes, such as enamelin, in their genomes; these unnecessary genes, which were inherited from toothed ancestors, show evidence of mutational decay, as predicted by evolutionary theory.

Credit

Paintings are by Carl Buell. Copyrighted to John Gatesy and Carl Buell.

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