Rhipidistia, also known as Dipnotetrapodomorpha, is a clade of lobe-finned fishes which includes the tetrapods and

lungfishes Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...

. Rhipidistia formerly referred to a subgroup of Sarcopterygii consisting of the

Porolepiformes Porolepiformes is an order of prehistoric lobe-finned fish which lived during the Devonian period (about 416 to 359 million years ago). The group contains two families: Holoptychiidae and Porolepididae. Porolepiformes was established by the ...

and

Osteolepiformes Osteolepiformes, also known as Osteolepidida, is a group of prehistoric lobe-finned fishes which first appeared during the Devonian period. The order contains the families Canowindridae, Megalichthyidae, Osteolepididae and Tristichopterida ...

, a definition that is now obsolete. However, as cladistic understanding of the vertebrates has improved over the last few decades, a monophyletic Rhipidistia is now understood to include the whole of Tetrapoda and the

. Rhipidistia includes Porolepiformes and Dipnoi. Extensive fossilization of lungfishes has contributed to many evolutionary studies of this group. Evolution of autostylic jaw suspension, in which the palatoquadrate bone fuses to the cranium, and the lymph pumping " lymph heart" (later lost in mammals and flying

birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

), are unique to this group. The precise time at which the choana evolved is debated, with some considering early rhipidistians as the first choanates.

Relationships

The cladogram presented below is based on studies compiled by Philippe Janvier and others for the ''Tree of Life Web Project'',Janvier, Philippe. 1997. Vertebrata. Animals with backbones. Version 01 January 1997 (under construction). http://tolweb.org/Vertebrata/14829/1997.01.01 in The Tree of Life Web Project, http://tolweb.org/ and Swartz 2012.

References

External links

palaeos.com page

Taxonomicon page
Rhipidistians Early Devonian first appearances Vertebrate subclasses Evolution of tetrapods {{paleo-lobefinned-fish-stub