''Letognathus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of rhizodont tetrapodomorph that lived during the Carboniferous period. Its remains come from the Blue Beach Member of the Horton Bluff Formation, near Hantsport,

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native En ...

. Like most rhizodonts, it was of relatively large size, had a large recurved fang at the symphysis of the lower jaw, and a row of three coronoid fangs along the length of the jaw in addition to its marginal dentition. ''Letognathus'' is important for rhizodont systematics because it retains a number of primitive features, such as ossified Meckel's cartilage, are not found in the genera '' Rhizodus'' and ''

Strepsodus ''Strepsodus'' is a genus of rhizodont lobe-finned fish that lived during the Carboniferous period. Fossils have been found in North America and Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, so ...

''.

Taxonomic History

The members of the Rhizodontida have nearly all had complex taxonomic historiesJeffery, J.E. 2006. The Carboniferous fish genera ''Strepsodus'' and ''Archichthys'' (Rhizodontida: Sarcopterygii): clarifying 150 years of confusion. ''Palaeontology'' 49: 113-132 due to earlier use of the genus ''Strepsodus'' as a

wastebasket taxon Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically define ...

. The taxon was originally assigned to the genus '' Rhizodus'' by John William Dawson and later to ''

'' by Arthur Smith Woodward. A new genus was erected for the Horton Bluff material based on a number of differences from either ''Strepsodus'' or ''Rhizodus''.

References

Prehistoric lobe-finned fish genera Mississippian fish of North America Rhizodonts {{paleo-lobefinned-fish-stub