Holocephali from the Irati Formation (Paraná Basin), Brazil: Origin, paleogeographical and paleoenvironmental considerations

Abstract

The Irati Formation (Permian, Cisuralian) has several types of aquatic vertebrates, including species of Chondrichthyes. Two members of the Irati Formation are recognized, Assistência (upper) and Taquaral (lower). A sandy facies, at the base of the Taquaral Member, is noteworthy by the richness of the Chondrichthyes. The Holocephali are the most abundant and the species Itapyrodus punctatus is the most common. Recent studies with several specimens revealed that some morphotypes must belong to different species of the genus Itapyrodus. This genus is endemic to the two Brazilian Basins, Parnaíba and Paraná and is not related to any other known genus, justifying the proposition of the family Itapyrodidae. A new genus and species of this family was identified, Fairchildodus rioclarensis. The presence of this endemic family is an argument, among others, for a proposed isolation during the time of deposition of the Irati.