Porolepiformes

Porolepiformes
Temporal range: 416–359 Ma
Devonian
Holoptychius sp.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sarcopterygii
Order: †Porolepiformes
(Jarvik, 1942)
Families

†Holoptychiidae
†Porolepididae

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 Swedish paleontologist Erik Jarvik, and were thought to have given rise to the salamanders and caecilians independently of the other tetrapods.[1] He based this conclusion on the shapes of the snouts of the aforementioned groups. This view is no longer in favour in Paleontology.[2]

Jarvik also claimed the existence of choanae in porolepiformes which linked them to tetrapods, but this has remained controversial.[3] Recent phylogenetic reconstruction places porolepiformes close to lungfishes.[4]

More recent evidence has shown that at least one genus Laccognathus was most likely amphibious.[5]

References

  1. ^ Jarvik, Erik. 1980. Basic structure and evolution of vertebrates. Vol. 1-2. Academic Press (London).
  2. ^ Schultze, Hans-Peter & Trueb, Linda (1991). Origins of the higher groups of tetrapods: controversy and consensus. Cornell University Press. p. 37. ISBN 9780801424977. http://books.google.com.ph/books?id=OeU-DVTz8M0C&lpg=PP1&hl=en&pg=PA37#v=onepage&q&f=false. 
  3. ^ Clement, G., 2001. Evidence for lack of choanae in the Porolepiformes. Journal of Vertebrate Paleontology, 21: 795–802.
  4. ^ Janvier , P., Early vertebrates. Oxford science publications. 1996, Oxford, New York: Clarendon Press; Oxford University Press.
  5. ^ Vorobyeva, E.I. (2006). "A new species of Laccognathus (Porolepiform Crossopterygii) from the Devonian of Latvia". Palaeont. J. (Physorg.com) 40 (3): 312–322. doi:10.1134/S0031030106030129.