Porolepiformes

Porolepiformes
Temporal range: 416–318 Ma Devonian and Carboniferous
Various genera
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Sarcopterygii
Clade: Rhipidistia
Clade: Dipnomorpha
Class: †Porolepimorpha
Order: †Porolepiformes
Jarvik 1942
Genera

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]

Porolepiform fossil (cast) from a Swedish natural history museum. Note that the description calls it a "Salamander fish", in accordance with Jarvik's obsolete hypothesis.
  1. ^ Nelson, Joseph S. (16 March 2016). Fishes of the World. ISBN 978-1-119-22081-7. OCLC 951128215.
  2. ^ Jarvik, Erik. 1980. Basic structure and evolution of vertebrates. Vol. 1–2. Academic Press (London).
  3. ^ Schultze, Hans-Peter & Trueb, Linda (1991). Origins of the higher groups of tetrapods: controversy and consensus. Cornell University Press. p. 37. ISBN 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. (2006). "A new species of Laccognathus (Porolepiform Crossopterygii) from the Devonian of Latvia". Paleontol. J. 40 (3). Physorg.com: 312–322. doi:10.1134/S0031030106030129. S2CID 129696592.