Synechodontiform sharks (Chondrichthyes, Neoselachii) from the Upper Cretaceous of Antarctica

• Main Authors: Klug, S, Kriwet, J, Lirio, M, Nuñez, H
• Other Authors: Arratia, G, null, Schultze, null, H-P, Wilson, MVH
• Format: Book Part
• Language: English
• Published: Verlag Dr. Friedrich Pfeil, Munich 2008
• Subjects: Antarctic; Herbert Sound; Lachman; Lachman Crags; Ross Island; The Antarctic; Antarc*; Antarctica; antarcticus; James Ross Island
• Online Access: http://hdl.handle.net/1983/a736ee1f-03af-4cec-bc3d-6c32cd81e644; https://research-information.bris.ac.uk/en/publications/a736ee1f-03af-4cec-bc3d-6c32cd81e644

The taxonomy of Upper Cretaceous synechodontiform sharks from the James Ross Basin, northern Antarctica, is reviewed. All material is from the Santa Marta Formation (late Coniacian – latest Campanian) of James Ross Island and contributes significantly to our knowledge of synechodontiform diversity and biogeographic patterns. Synechodontiforms are represented by two taxa, Sphenodus and Paraorthacodus. The teeth of the Antarctic Sphenodus species differ from most known species assigned to this genus. However, the imperfect preservation does not allow any specific identification of this Antarctic shark. The size of its teeth indicates that this shark probably measured at least 5 m in total length. A new species, Paraorthacodus antarcticus, is introduced. Paraorthacodus is confined to the Santa Marta Formation (Santonian to early Campanian Lachman Crags and late Campanian to early Maastrichtian Herbert Sound members), whereas Sphenodus occurs in the Herbert Sound Member and the Maastrichtian López de Bertodano Formation. The occurrence of synechodontiform sharks in the James Ross Basin correlates with an interval of enlargement of the trans-equatorial Tethyan seaway within the Coniacian-Maastrichtian interval. The absence of all synechodontiforms in Antarctica after the K/T boundary, conversely, concurs with a drop in surface water temperatures. The taxonomy of Upper Cretaceous synechodontiform sharks from the James Ross Basin, northern Antarctica, is reviewed. All material is from the Santa Marta Formation (late Coniacian – latest Campanian) of James Ross Island and contributes significantly to our knowledge of synechodontiform diversity and biogeographic patterns. Synechodontiforms are represented by two taxa, Sphenodus and Paraorthacodus. The teeth of the Antarctic Sphenodus species differ from most known species assigned to this genus. However, the imperfect preservation does not allow any specific identification of this Antarctic shark. The size of its teeth indicates that this shark probably measured at least 5 m in total length. A new species, Paraorthacodus antarcticus, is introduced. Paraorthacodus is confined to the Santa Marta Formation (Santonian to early Campanian Lachman Crags and late Campanian to early Maastrichtian Herbert Sound members), whereas Sphenodus occurs in the Herbert Sound Member and the Maastrichtian López de Bertodano Formation. The occurrence of synechodontiform sharks in the James Ross Basin correlates with an interval of enlargement of the trans-equatorial Tethyan seaway within the Coniacian-Maastrichtian interval. The absence of all synechodontiforms in Antarctica after the K/T boundary, conversely, concurs with a drop in surface water temperatures.