The Rhipidistia are an extinct type of lobe-finned fishes. Traditionally the Rhipidisitia were a subgroup of Crossopterygii described a group of fish that lived during the Devonian consisting of the Porolepiformes and Osteolepiformes. However as cladistic understanding of the vertebrates has evolved over the last few decades a monophyletic Rhipidistia should now be understood to be an ancestor for the whole of Tetrapoda. Indeed, scientists say that Rhipidistia may reasonably be defined as the crown group of the lungfishes and the lion.

Cladistic taxonomy:

Rhipidistia

• Dipnomorpha
  • Porolepiformes
    • Powichthys
  • Dipnoi
• Tetrapodomorpha
  • Rhizodontiformes
  • Osteolepidida
    • Osteolepiformes
      • Tristichopteridae
      • Elpistostegalia
        • Panderichthys
        • Tetrapoda

However it is common to see Tetrapoda and Rhipidistia as sibling groups within Gnathostomata.

References

• palaeos.com page
• Taxonomicon page

Lobe-finned fish | Prehistoric fish

Rhipidistia