page_title: List of extinct cetaceans
section_title: Family Mammalodontidae
hierarchical_section_title: List of extinct cetaceans / Suborder Mysticeti / Family Mammalodontidae
caption_attribution_description: Janjucetus skull Melbourne Museum Photo:Cas Liber
context_page_description: The list of extinct cetaceans features the extinct genera and species of the order Cetacea. The cetaceans are descendants of land-living mammals, the even-toed ungulates. The earliest cetaceans were still hoofed mammals. These early cetaceans became gradually better adapted for swimming than for walking on land, finally evolving into fully marine cetaceans.
  This list currently includes only fossil genera and species. However, the Atlantic population of gray whales became extinct in the 18th century, and the baiji was declared "functionally extinct" after an expedition in late 2006 failed to find any in the Yangtze River.
context_section_description: (jr synonym Janjucetidae)
  (Late Oligocene)
  Janjucetus
  Mammalodon
caption: Janjucetus hunderi
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