Thursday, July 14, 2011

[Palaeontology • 2008] Torvoneustes (Dakosaurus) carpenteri • new metriorhynchid crocodilian (Upper Jurassic) from Wiltshire, UK

Torvoneustes (Dakosaurus) carpenteri
(Wilkinson, Young, & Benton, 2008)

Recent revision of the marine metriorhynchid crocodilians indicates that a partial skull previously assigned to the species Metriorhynchus superciliosus and newly discovered postcranial elements from the Kimmeridge Clay of Westbury, Wiltshire belong to a new species of metriorhynchid. This material is herein described and referred to a new species of the genus Dakosaurus, characterised by four apomorphies: the size and shape of the enlarged supratemporal fossae; relatively large teeth, and half the number in relatives; the robust and unornamented cranium; and the angle that the prefrontal makes with the long axis of the skull. In a new phylogenetic analysis, Dakosaurus carpenteri sp. nov. is the basal member of a clade containing also D. maximus and D. andiniensis: it is not so short-snouted and its teeth are not so few and large as in the other two species, but the new form illustrates the ecological transition among metriorhynchids from a piscivorous diet to high-order carnivory.

Keywords: Metriorhynchidae, Kimmeridgian, Jurassic, England, Metriorhynchus, Dakosaurus, Thalattosuchia

• Dakosaurus carpenteri Wilkinson, Young, & Benton, 2008
• Geosaurus carpenteri Young & de Andrade, 2009
• Torvoneustes carpenteri Andrade, Young, Desojo & Brusatte, 2010

Wilkinson, L.E., Young, M.T. and Benton, M.J. 2008. "A new metriorhynchid crocodilian (Mesoeucrocodylia: Thalattosuchia) from the Kimmeridgian (Upper Jurassic) of Wiltshire, UK". Palaeontology. 51 (6): 1307–1333. doi:10.1111/j.1475-4983.2008.00818.x
Andrade, M.B.D., Young, M.T., Desojo, J.B. and Brusatte, S.L. 2010. The evolution of extreme hypercarnivory in Metriorhynchidae (Mesoeucrocodylia: Thalattosuchia) based on evidence from microscopic denticle morphology. Journal of Vertebrate Paleontology. 30 (5): 1451–1465.