Dorypterus hoffmanni was a stem–actinopterygian fish that lived during the late Permian, around 259-254 million years ago, in shallow warm lagoons covering what is now northwestern Europe.
About 13cm long (~5″), it had a tall narrow disc-shaped body convergently similar to modern reef fish, and it was mostly scaleless with only a few scales on its underside, below its pectoral fins, and along the top of its tail. It also appears to have been toothless, and probably used its large scissor-like jaws to snip off mouthfuls of soft food such as algae.
But its most distinctive feature was its highly elongated pennant-like dorsal fin, which may be an example of sexual dimorphism – fossils of short-finned individuals have also been found, and although they were originally named as a separate species (Dorypterus althausi) they probably actually represent female D. hoffmani.
References:
- Gill, E. Leonard. “XXXI.—The Permian Fish Dorypterus.” Earth and Environmental Science Transactions of The Royal Society of Edinburgh 53.3 (1925): 643-661. https://doi.org/10.1017/S0080456800027526
- Nelson, Joseph S., Terry C. Grande, and Mark VH Wilson. Fishes of the World. John Wiley & Sons, 2016. https://www.researchgate.net/publication/301290410_Fishes_of_the_World_Fifth_Edition
- Westoll, T. Stanley. “The Permian fishes Dorypterus and Lekanichthys.” Proceedings of the Zoological Society of London B111 (1941): 39-58. https://doi.org/10.1111/j.1469-7998.1941.tb00042.x
- Wikipedia contributors. “Dorypterus” Wikipedia, 23 Dec. 2024, https://en.wikipedia.org/wiki/Dorypterus