Onychodontida

Onychodontiformes (also known as Onychodontida and Struniiformes) is an order of prehistoric sarcopterygian fish that lived during the Devonian period. The onychodontiforms are generally regarded as early-diverging members of the coelacanth lineage.

Onychodus (, from Greek meaning "claw-tooth") is a genus of prehistoric lobe-finned fish which lived during the Devonian Period (Eifelian - Famennian stages, around 374 to 397 million years ago). It is one of the best known of the group of onychodontiform fishes. Scattered fossil teeth of Onychodus were first described from Ohio in 1857 by John Strong Newberry. Other species were found in Australia, England, Norway and Germany showing that it had a widespread range.

Strunius is an extinct genus of lobe-finned fish from the Late Devonian period of Germany and Latvia. The genus contains two named species, S. rolandi and S. walteri, as well as a third unnamed species from the Lode Quarry of Latvia.

Qingmenodus is a genus of prehistoric lobe-finned fish. Fossils of Qingmenodus were found in China and date back to the Early Devonian period. Qingmenodus reveals the first well-ossified otoccipital braincase in onychodonts. Palaeontologists believe that Qingmenodus was one of the oldest onychodont fish.