Archaeoceti

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Archaeoceti
Fossil range: Eocene to Miocene (non-Autocetan)

Pakicetus, one of the very first archeocetids

Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Cetacea
Suborder:	Archaeoceti

Families and Clades

see text

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 (perhaps of the family Hippopotamidae which includes the modern Hippopotamus). The ancestors of archaeocetes probably diverged from the artiodactyls around the time of the Cretaceous–Tertiary extinction event. Most archeocetes had hind limbs, suggesting that they were likely fully terrestrial. As the Eocene epoch progressed the archaeocetes were becoming 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 archaeocetes became extinct in the Oligocene, which was probably a basilosaurid. Another explanation is climate change; as Miocene progressed, the ocean became cooler and cooler. They may have become extinct in the combination of the two factors: competition and climate change.

The remingtonocetids

The more aquatic Basilosaurus.

1 Taxonomy and Phylogeny
- 1.1 Phylogeny
2 See also
3 References
4 External links

[edit] Taxonomy and Phylogeny

Superorder Cetartiodactyla
- 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
        
        Genus Rodhocetus
      - Subfamily Indocetinae
        
        Genus Protocetus
        
        Genus Georgiacetus
      - Family Basilosauridae
        
        Subfamily Basilosaurinae
        
        Genus Basilosaurus
        
        Subfamily Dorudontinae
        
        Genus Zygorhiza
        
        Genus Dorudon
  - Suborder Mysticeti
  - Suborder Odontoceti
    - (unranked) Squalodontoidea
      - Genus Squalodon

[edit] Phylogeny

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

[edit] See also

Cetaceans Portal

[edit] References

This article does not cite any references or sources. (June 2008)
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[edit] External links

Categories: Early whales | Cetaceans | Miocene extinctions

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Archaeoceti

From Wikipedia, the free encyclopedia

Contents

[edit] Taxonomy and Phylogeny

[edit] Phylogeny

[edit] See also

[edit] References

[edit] External links

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