Osteoglossiformes/ˌɒstiːoʊˈɡlɒsɪfɔːrmiːz/ (Greek: "bony tongues") is a relatively primitive order of ray-finned fish that contains two sub-orders, the Osteoglossoidei and the Notopteroidei. All of at least 245 living species inhabit freshwater. They are found in South America, Africa, Australia and southern Asia, having first evolved in Gondwana before that continent broke up.[2] In 2008, several new species of marine osteoglossiforms were described from the Danish EoceneFur Formation, dramatically increasing the diversity of this group. This implies that the Osteoglossomorpha is not a primary freshwater fish group with the osteoglossiforms having a typical Gondwana distribution.[3]
The mooneyes (Hiodontidae) are often classified here, but may also be placed in a separate order, Hiodontiformes.
Members of the order are notable for having toothed or bony tongues, and for having the forward part of the gastrointestinal tract pass to the left of the oesophagus and stomach (for all other fish it passes to the right). In other respects, osteoglossiform fishes vary considerably in size and form; the smallest is Pollimyrus castelnaui, at just 2 centimetres (0.79 in) long, while the largest, the arapaima (Arapaima gigas), reaches as much as 2.5 metres (8.2 ft).[2]
^ abGreenwood, P.H. & Wilson, M.V. (1998). Paxton, J.R. & Eschmeyer, W.N. (eds.). Encyclopedia of Fishes. San Diego: Academic Press. pp. 81–84. ISBN0-12-547665-5.
^Bonde, N., 2008: Osteoglossomorphs of the marine Lower Eocene of Denmark – with remarks on other Eocene taxa and their importance for palaeobiogeography. Geological Society, London, Special Publications; 2008; v. 295; p. 253-310
^Lavoué, S., Sullivan J. P., & Hopkins C. D. (2003): Phylogenetic utility of the first two introns of the S7 ribosomal protein gene in African electric fishes (Mormyroidea: Teleostei) and congruence with other molecular markers. Biological Journal of the Linnean Society. 78, 273-292. PDFArchived 2014-10-30 at the Wayback Machine
^Sullivan, J. P., Lavoué S., & Hopkins C. D. (2000): Molecular systematics of the African electric fishes (Mormyroidea: Teleostei) and a model for the evolution of their electric organs. Journal of Experimental Biology. 203, 665-683. PDFArchived 2014-10-30 at the Wayback Machine