Archaeoceti

Archaeoceti Temporal range: Eocene–Oligocene PreЄ Є O S D C P T J K Pg N
Cynthiacetus and Ambulocetus skeletons
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Cetacea
Suborder:	Archaeoceti † Flower, 1883
Families and Clades
see text

The more aquatic Basilosaurus.

Archaeocetes, or "ancient whales", are a paraphyletic group of cetaceans that gave rise to the modern cetaceans.

The archaeocetes were once thought to have evolved from the mesonychids, based on dental characteristics. However, recent studies in molecular genetics and non-dental morphology show that the first whales or the archaeoceti most likely evolved from artiodactyls; genetic evidence indicates that their closest living relatives are the family Hippopotamidae which includes the modern hippopotamus. The ancestors of archaeocetes probably diverged from the other artiodactyls around the time of the Cretaceous–Tertiary extinction event.

Most archaeocetes had hind limbs, suggesting that they were fully terrestrial. As the Eocene epoch progressed, the archaeocetes became less terrestrial and more aquatic. Before the Eocene epoch came to an end, one group of archaeocetes, the basilosaurids, gave rise to early modern cetaceans. The archaeocetes suffered a heavy loss of genera during the Eocene-Oligocene extinction event, but some species survived into the Oligocene. The last archaeocete, which was probably a basilosaurid, became extinct in the Oligocene. They may have become extinct from a combination of competition and climate change.

Taxonomy

• Order Cetacea
  • Suborder Archaeoceti
    • Family Pakicetidae
      • Genus Pakicetus
      • Genus Nalacetus
      • Genus Ichthyolestes
    • Family Ambulocetidae
      • Genus Ambulocetus
      • Genus Gandakasia
      • Genus Himalayacetus
    • Family Remingtonocetidae
      • Genus Andrewsiphius
      • Genus Attockicetus
      • Genus Dalanistes
      • Genus Kutchicetus
      • Genus Remingtonocetus
    • Family Protocetidae
      • Subfamily Georgiacetinae
        • Genus Babiacetus
        • Genus Carolinacetus
        • Genus Eocetus
        • Genus Georgiacetus
        • Genus Natchitochia
        • Genus Pappocetus
      • Subfamily Makaracetinae
        • Genus Makaracetus
      • Subfamily Protocetinae
        • Genus Artiocetus
        • Genus Crenatocetus
        • Genus Gaviacetus
        • Genus Indocetus
        • Genus Maiacetus
        • Genus Protocetus
        • Genus Qaisracetus
        • Genus Rodhocetus
        • Genus Takracetus
    • Family Basilosauridae
      • Subfamily Basilosaurinae
        • Genus Basilosaurus
        • Genus Basiloterus
      • Subfamily Dorudontinae
        • Genus Ancalecetus
        • Genus Chrysocetus
        • Genus Cynthiacetus
        • Genus Dorudon
        • Genus Saghacetus
        • Genus Zygorhiza
      • Subfamily Kekenodontinae
        • Genus Kekenodon
        • Genus Phococetus
      • Subfamily Stromeriinae
        • Genus Stromerius

Geological ages of different Archaeoceti.

Phylogeny

Cetartiodactyla
|--Cetacea
|  |--Pakicetidae
|  `--+--Ambulocetidae
|     `--+--Remingtonocetidae
|        `--Protocetidae
|           |--Georgiacetus
|           `--Basilosauridae
|              |--Basilosaurus
|              `--+--Dorudon
|                 `--Autoceta
|                    |--Odontoceti
|                    |  |--Squalodontoidea
|                    |  |  |--Squalodontidae
|                    |  |  `--Rhabdosteidae
|                    |  `--Physeteroidea
|                    `--Mysticeti
`--Artiodactyla

See also

• Evolution of cetaceans
• Cetaceans
• Mesonychid
• Cetartiodactyla

External links

• Archaeoceti
• Archaeoceti and Basilosaurus