Porolepiformes Explained

Porolepiformes is an order of prehistoric lobe-finned fish which lived during the Devonian period (about 416 to 359 million years ago). They are thought to represent the sister group to lungfish (class Dipnoi).^[1] 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.^[2] He based this conclusion on the shapes of the snouts of the aforementioned groups. This view is no longer in favour in Paleontology.^[3]

Jarvik also claimed the existence of choanae in porolepiformes which linked them to tetrapods, but this has remained controversial.^[4] Recent phylogenetic reconstruction places porolepiformes close to lungfishes.^[5]

More recent evidence has shown that at least one genus Laccognathus was most likely amphibious.^[6]

Phylogeny

Mikko's Phylogeny Archive ^[7]

Notes and References

1. Book: Nelson, Joseph S. . Fishes of the World . 16 March 2016 . 978-1-119-22081-7 . 951128215.
2. Jarvik, Erik. 1980. Basic structure and evolution of vertebrates. Vol. 1–2. Academic Press (London).
3. Book: Schultze, Hans-Peter . Trueb, Linda . amp . Origins of the higher groups of tetrapods: controversy and consensus. Cornell University Press. 1991. 37. 978-0-8014-2497-7.
4. Clement, G., 2001. Evidence for lack of choanae in the Porolepiformes. Journal of Vertebrate Paleontology, 21: 795–802.
5. Janvier, P., Early vertebrates. Oxford science publications. 1996, Oxford, New York: Clarendon Press; Oxford University Press.
6. Vorobyeva, E.I.. Emiliya Ivanovna Vorobyeva. 2006. A new species of Laccognathus (Porolepiform Crossopterygii) from the Devonian of Latvia . Paleontol. J.. 40. 3. 312 - 322. Physorg.com. 10.1134/S0031030106030129. 129696592.
7. Haaramo, Mikko . 2003 . Porolepiformes . In Mikko's Phylogeny Archive . November 4, 2013.