Description: This is a fine example of the lungfish Rhinodipterus. It has long been believed that air breathing developed in lungfish living in freshwater habitats, and then spread to marine taxa. Specimens of this genus found in Australia last year have raised doubts about this long-held hypothesis. The long mouth cavity of this fish coupled with the articulation of the cranial ribs are much like those of the extant freshwater lungfishes of today. While the invasion of freshwater habitats from the marine realm was previously thought to be the driving force in the development of air breathing, this new data has led some researchers to theorise that a drop in ambient oxygen levels was more likely. Examples such as this are rarely available. The repaired crack detracts but little from the specimen offered here, the ONLY one I have ever been able to secure.