Description: This is a fine example of the first lungfish described in 1828. It is one of the oldest to possess cranial ribs, and is thus believed to have been capable of gulping air, allowing it to extract oxygen directly from the atmosphere. The lungfish arose during the early Devonian, reaching a peak in diversity by the Late Devonian. While all early Dipnooans were marine, all known from the Carboniferous on have been freshwater denizens. A few survive today in Africa, South America, and Australia. The shine to the specimen is the result of cosmine, a layer of shiny bony tissue that consists of an external enameloid layer over a dentine layer. Cosmine is thought to have comprised apart of the skin’s complex vascular system. This cosmine layer was lost in most Dipnoan by the Late Devonian in favor of thinner scales. Interestingly, the deposits of Caithness also hold the remains of Palaeospondlyus, a much smaller fish thought by some to be a larval form of Dipterus because of similar cranial structures. See my other offerings for an example.

Also see: Paleozoic Fish Fossils