Definition of "cetaceans" [cetaceans]

• Plural form of cetacean. (noun)

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• "No one can dispute that cetaceans, that is whales and dolphins, are highly intelligent."
• "The marine mammals known as cetaceans originated about 50 million years ago in south Asia, but their terrestrial ancestor is something of a mystery."
• "The symphyseal area (the region where the jaw tips meet) is unfused, as is the case in all mysticetes (even the most basal ones) but not other cetaceans, meaning that the two halves of the jaw can stretch apart at their tips somewhat."