Akmonistion is an extinct genus of cartilaginous fish that lived in the Early Carboniferous. The genus contains a single species, A. zangerli, discovered by Stan Wood in 1982.[1] It is distinguished by an unusual enlarged formation of the dorsal fin, called a "spine-brush complex", of unknown function. This is also found in the better known genus Stethacanthus. Remains have only been found near Bearsden in Scotland.[2][3] The genus name is derived from the Ancient Greek “akmon” (“anvil”) + “istion” (“sail”) referring to the appearance of its first dorsal fin.[2] It reached 62 cm (24 in) in length.[2]
| Akmonistion Temporal range: | |
|---|---|
 | |
| Holotype fossil | |
 | |
| Reconstruction | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Order: | †Symmoriiformes |
| Family: | †Stethacanthidae |
| Genus: | †Akmonistion |
| Species: | †A. zangerli |
| Binomial name | |
| †Akmonistion zangerli Coates & Sequeira, 2001 | |