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iTetrapodomorphs Fossil range: late Early Devonian - Recent
Image:Tiktaalik.png The basal tetrapodomorph Tiktaalik.
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Sarcopterygii Subclass: Tetrapodomorpha Ahlberg, 1991
Subgroups
See text

Tetrapodomorpha is a clade of vertebrates, consisting of sarcopterygians with a number of features of tetrapods. Primitive forms, like Tiktaalik, have been referred to as "fishapods" by their discoverers, since they were half-fish half-tetrapods, at least in appearance.

Tetrapodomorpha contains the true tetrapods and several groups of related lobe-finned fishes, collectively known as the osteolepiforms.

Among the characters defining the tetrapodomorphs are modifications to the fins, notably a humerus with convex head articulating with the glenoid fossa (the socket of the shoulder joint).

Tetrapodomorph fossils are known from the early Devonian onwards, and include Osteolepis and Panderichthys.

[edit] Taxonomy and Phylogeny

• Class Sarcopterygii
  • Subclass TETRAPODOMORPHA
    • Kenichthys
    • Order Rhizodontida
    • Superorder Osteolepidida (or Osteolepiformes)
      • Family Osteolepididae
        • Osteolepis
      • Family Tristichopteridae
        • Eusthenopteron
      • Family Megalichthyidae
      • Family Canowindridae
      • (unranked) Elpistostegalia
        • Order Panderichthyida
        • Tiktaalik
        • Livoniana
        • Metaxygnathus
        • Ventastega
        • Superclass Tetrapoda

After Benton, 2004 [1]:

[edit] References

• Mikko Haaramo. Tetrapodomorpha - Terrestrial vertebrate-like sarcopterygians. Retrieved on 6 April, 2006.
• P. E. Ahlberg and Z. Johanson (1998). "Osteolepiforms and the ancestry of tetrapods". Nature 395 (6704): 792–794. DOI:10.1038/27421.
• Michel Laurin, Marc Girondot and Armand de Ricqlès (2000). "Early tetrapod evolution". TREE 15 (3).ca:Tetrapodomorf