Phosphatized soft‐bodied squids from the Jurassic Oxford Clay

Abstract

A diagenetic case study of phosphatized soft-bodied squids from the lower part of the Oxford Clay of Christian Malford, Wiltshire, has dated mineralization in relation to burial history. Complete squids with mantle tissues were examined under the SEM as uncoated specimens at low KV. A simple stage attachment designed for this purpose is described. Soft-parts are preserved in three dimensions and must therefore have been mineralized prior to decay-induced tissue collapse. Such mineralization occurred near to the anoxic/oxic boundary in the ‘soupy’ upper layer of organic-rich sediment. In acrobic conditions, phosphates were liberated to pore-water solution from decomposing organic matter and became adsorbed to ferric hydroxides within sediment. The reduction of these ferric hydroxides at the anoxic-oxic interface liberated phosphates to solutions which were conccntrated in the decomposing carcasses of the squids. This mineral concentration was favoured by the development of a high pH reducing environment around the carcass and possibly by complexing with protcolipids liberated by decomposition of animal matter. ▭Soft-part preservation, phosphatization, SEM techniques, cephatopod. Oxford Clay, Wiltshire, England.