Rhipidistia

The Rhipidistia, also known as dipnotetrapodomorphs (formally Dipnotetrapodomorpha)[1] are a clade of lobe-finned fishes which include the tetrapods and lungfishes. Rhipidistia formerly referred to a subgroup of Sarcopterygii consisting of the Porolepiformes and Osteolepiformes, a definition that is now obsolete.[2] 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 lungfishes.

Rhipidistians
Temporal range:
Early Devonian - Present, 416–0 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Sarcopterygii
Clade: Rhipidistia
Subgroups

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, is 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,[3] and Swartz 2012.[4]

Sarcopterygii
 

†Onychodontidae

 
 

Actinistia (coelacanths)

 
Rhipidistia
 

†Styloichthys

 
Dipnomorpha
 

†Porolepiformes

 
 

Dipnoi (lungfishes)

 
 
Tetrapodomorpha
 

?†Tungsenia

 
 

†Kenichthys

 
 
 

†Rhizodontiformes

 
 
 

?†Thysanolepidae

 
 

†Canowindridae

 
 
 

†Osteolepiformes

 
Eotetrapodiformes
 

†Tristichopteridae

 
 
 

†Tinirau

 
 
 

†Platycephalichthys

 
Elpistostegalia
 

†Panderichthys

 
 
 

†Elpistostegidae

 
Stegocephalia
 

†Elginerpetonidae

 
 
 
 

†Metaxygnathus

 
 

†Ventastega

 
 
 

Tetrapoda

 
 
 
 
 
 
 
 
 
 
 
 
 
 
gollark: No, I like that one.
gollark: The problems I have with our system are more about issues we ended up with than the entire general concept of markets.
gollark: You could complain that this is due to indoctrination of some sort by... someone, and maybe this is true (EDIT: but you could probably just change that and it would be easier than reworking the entire economy). But you can quite easily see examples of people just not actually caring about hardships far away, and I think this is a thing throughout history.
gollark: What I'm saying is that, despite some problems, our market system is pretty effective at making the things people involved in it want. And most people do not *actually* want to help people elsewhere much if it comes at cost to them.
gollark: Yep!

References
  1. Joseph S., Nelson (19 May 2006). Fishes of the World. John Wiley & Sons. p. 461. ISBN 978-0-471-75644-6. Retrieved 9 May 2015.
  2. "Encyclopædia Britannica". Retrieved 3 April 2014.
  3. 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/
  4. Swartz, B. (2012). "A marine stem-tetrapod from the Devonian of Western North America". PLoS ONE. 7 (3): e33683. doi:10.1371/journal.pone.0033683. PMC 3308997. PMID 22448265.


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