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

The Irati Formation (Permian, Cisuralian) has several types of aquatic vertebrates, including species of Chondrichthyes. Two members of the Irati Formation are recognized, Assistencia (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, Parnaiba and Parana 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.

Automated summary

The Irati Formation in the Permian period contains various types of aquatic vertebrates, including Chondrichthyes species. The most common species found is Itapyrodus punctatus, belonging to the Holocephali. Recent studies have identified different species within the genus Itapyrodus and discovered a new genus and species, Fairchildodus rioclarensis, belonging to the endemic family Itapyrodidae. The presence of this endemic family suggests isolation during the deposition of the Irati Formation.