cetacean
Cetaceans are any member of the infraorder Cetacea, aquatic mammals which are mostly marine. This infraorder includes two extant parvorders - odontoceti and mysteceti - which share a common ancestor by means of an extinct parvorder, archaeoceti. Cetacea as an infraorder is related most to the hippopotamuses and fall under the order Artiodactyla accordingly, having diverged from even-toed ungulates 45 to 53 million…
