ASL STEM

Definition

Lungfish is any sarcopterygian fish of the taxon Dipnoi, characterized by platelike teeth and lobed, paired fins, with modern forms typified by functional lungs and the caudal fin confluent with the dorsal and anal fins. While some consider Dipnoi to be a subclass of Sarcopterygii, Nelson (2006) considers the subclass to be Dipnotetrapodomorpha, with the dipnoians (lungfishes) comprising two superorders within this subclass, Dipterimorpha and Ceratodontimorpha, the later including the living lungfishes. The dipnoans are well represented in the fossil record, but there are only six extant species, all freshwater species.

Source: Wikipedia