A new lungfish (Ceratodontoidei, Dipnoi) from the Early Jurassic of Chongqing, China.

Dipnoi (lungfishes) are a group of air-breathing sarcopterygian fishes that survived over hundreds of millions of years and their crown members (Neoceratodus, Lepidosiren and Protopterus) are among the closest living relatives of the tetrapods. After the end-Triassic mass extinction, dipnoan diversity was supposedly low, and all Early Jurassic remains were once ascribed to a single genus, Ceratodus on the basis of isolated tooth plates. Later studies indicate that Ceratodus might be an assemblage of forms with disparate cranial morphology. Here, we report the discovery of a new lungfish, Sinoceratodus fortunus gen. et sp. nov., based on three articulated specimens from the Early Jurassic (Sinemurian, ~ 199–193 Ma) lacustrine deposits of Chongqing, China. The new finding represents the best-preserved lungfish known so far from the Jurassic with a unique combination of features (e.g., anterior skull bone marked by sensory lines and presence of supraorbital bone) previously unknown in any genera among Mesozoic lungfishes, and significantly adds to our knowledge regarding the morphological diversity of this clade. Results of phylogenetic studies recover Sinoceratodus as a sister taxon to gnathorhizids within the Dipnoi crown and provide new insights into the origin of modern African and South American lungfishes.