Ptychoceratodus
Ptychoceratodus is an extinct genus of lungfish living from Early Triassic to Middle Jurassic. It was established by Otto Jaekel for one species ("P. runcinatus"), transferred from "Ceratodus" genus. Type species is "P. serratus" from the Middle Triassic of Switzerland and Germany. "Ptychoceratodus" had two pairs of massive dental plates, bearing 4-6 acute ridges. Its skull roof was composed from massive, plate-like bones. In the central part of skull roof was localized an unossified fenestra. Most of the "Ptychoceratodus" findings are isolated dental plates, some associated with jaws. Other parts of skull or postcranial skeleton are relatively  rarely found as fossils. The anatomy of skull is the best recognized in "P. serratus", whereas less complete cranial material is available also for "P. concinuus, P. phillipsi," and "P. rectangulus". Although "Ptychoceratodus" is known exclusively from the Triassic and Jurassic, there were also Cretaceous specimens referred to this genus. However, they are more often regarded as representants of "Metaceratodus". "Ptychoceratodus" is the only member of the family Ptychoceratodontidae. The first named species is "P. phillipsi" by Louis Agassiz in 1837 as a species of "Ceratodus" and later moved to "Ptychoceratodus" genus. Occurrences of "Ptychoceratodus" come mainly from Europe. However , occurrences from other continents suggest it was dispersed globally during the Triassic. After 2010, the new fossil material behind the Europe was reported from South America, India, and Greenland Fossil distribution. Fossils of "Ptychoceratodus" have been found in: