The first record of the chimaeroid genus Edaphodon (Chondrichthyes, Holocephali) from Antarctica (Snow Hill Formation, Late Cretaceous, James Ross Island)

SOLEDAD GOUIRIC CAVALLI; CABRERA, DANIEL ALFREDO; CIONE, ALBERTO LUIS; O'GORMAN, JOSÉ; CORIA, RODOLFO; FERNÁNDEZ, MARTA; IGLESIAS, ARI; REGUERO, MARCELO

Auckland

Conferencia; 2014 SCAR OPEN SCIENCE CONFERENCE; 2014

Holocephali (rat fishes, elephant fishes and relatives) is a relatively poorly diversified marine chondrichthyan clade that ranges from the Paleozoic to the Recent. It radiated during the Cretaceous but its diversity diminished during the Cenozoic. The most distinctive character of the group is its bradyodont dentition. The dentition of chimaeroid fishes consists of two pairs of tooth plates in the upper jaw and one pair in the lower jaw. Chimaeroid tooth plates show hypermineralized tissue concentrated in areas called tritors, which never spread over the entire occlusal surface like in other holocephalian fishes. Associated holocephalian dentitions are uncommon. The specimen reported here is three-dimensionally preserved and consists of an almost complete dentition represented by five big sized tooth plates. The material was collected in the late Campanian Herbert Sound Member of the Snow Hill Island Formation in the James Ross Island, Antarctica. According to the size of the tooth plates, this specimen is one of the largest chimaeroid fish known. Also, this finding represents the oldest and the most complete dentition of a holocephalian fish from the Southern Hemisphere and the first record of the genus Edaphodon from the continent. Moreover and according to a character combination the specimen could be a new species.