Icthyobrachis is an aquatic, neotenic taxon of small aquatic lepospondyls. Unlike its relatives, the reptiliomorphs, it had soft skin, and most importantly, feathery gills. that lived during the Late Carboniferous.
Discovery[]
Icthyobrachis was first discovered in 2020 in a Carboniferous-aged coal mine just in Scotland. The holotype, AMNM 55449 was taken to the American Museum of Natural History (AMNH) and was thoroughly identified by palaeontologists. The holotype is displayed in the Fossil Hall of AMNH.
Description[]
Icthyobrachis was presumably slender and slim. The flippers that were its limbs were flat, attached onto weak bones (a reduced, lightly ossified pelvis and shoulder blades and girdle). The estimates of its length were 1 to 1.5 metres in length. They are known from few ossified ribs and some skull fragments, making it a very problematic and enigmatic organism. The tail is well preserved, having a large fluke at the end to aid in swimming.
Classification[]
Due to the shape of the head, bones in the skull and identification of the humeri put it as a diplocaulid, related to amphibians like Diplocaulus, in the family diplocaulidae. It is placed in its own independent family, Neoicthynae, or 'advanced/new fish'.
Palaeobiology[]
It is speculated that this organism is a fully aquatic, neotenic (like axolotls) creature which had feathery gills. Because of such few and fragmented fossils, Icthyobrachis had sharp teeth, equipped for catching fish, and possibly griffinflies like Meganeura.