Arm hooks of coleoid cephalopods from the Jurassic succession of the Wessex Basin, Southern England

Abstract

© 2018 The Geologists' Association The Jurassic succession of the Wessex Basin – especially that cropping out within the Dorset and East Devon Coast World Heritage Site – contains important lagerstätten for coleoid cephalopods. The Blue Lias and Charmouth Mudstone formations of West Dorset, the Oxford Clay Formation of North Wiltshire and the Kimmeridge Clay Formation of Purbeck have provided large numbers of important body fossils that inform our knowledge of coleoid palaeobiology, including the hooks present in the arms. Isolated hooks are also found in the processed residues studied by micropalaeontologists and these occurrences can be used – in some cases – to record the presence of key taxa in the absence of well-preserved body fossils. While some hook morphotypes can be attributed to known species, there are many forms of hook described where the parent animal remains unknown. The present state of our knowledge of the Jurassic assemblages in the Wessex Basin is presented and remaining issues identified.