The oldest hexanchiform shark from the Southern Hemisphere (Neoselachii; Early Cretaceous, Antarctica)

• Published in: Antarctic Science
• Main Authors: Cione, Alberto Luis, Medina, Francisco
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2009
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; Antarctic; Antarctic Peninsula; Ross Island; Kotick; Kotick Point; Antarc*; Antarctic Science; Antarctica; James Ross Island
• Online Access: http://dx.doi.org/10.1017/s0954102009990228; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102009990228

Abstract The oldest record of the hexanchiform sharks from the Southern Hemisphere and the second chondrichthyan report known from Carboniferous to Early Cretaceous beds in Antarctica is given. The material was collected in late Aptian rocks of the Kotick Point Formation outcropping in the western part of James Ross Island, near Antarctic Peninsula. It consists of an isolated tooth assignable to a hexanchiform different from the other described genera. The tooth shows putative plesiomorphic cusp (few cusps, no serrations) and apomorphic root characters (relatively deep, quadrangular). It could be related to a species close to the origin of Hexanchus (unknown in beds older than Cenomanian).