We are pleased to have another talk via Zoom on Wed 16 Sept 2020 at 7.15 for a prompt 7:30 pm start.
Malcolm Hart (Emeritus Professor, University of Plymouth).
Discoveries of some exquisite specimens of soft parts of squid-like cephalopods have been found in the fossil record in the Wessex Basin. They are around 190–160 million years’ old, and there is exceptional preservation of eyes, ink sacks, beaks and arm hooks. Balancing organs, ‘statoliths’, of aragonite have also survived and show internal (daily?) growth lines.
There are specimens of fossil squid-like cephalopods in the Natural History Museum (London) and Lyme Regis Museum, some collected by both Mary Anning and Henry De La Beche. When the GWR railway was built from Swindon to Bristol, local palaeontologist Joseph Pearce uncovered fossils at Christian Malford that caused great excitement as soft parts of squid-like animals were preserved. The ink sacks and the muscle scars survived and reconstruction of the creatures from the arms, some with pairs of hooks could be attempted. A specimen from Bristol Museum & Art Gallery has non-paired hooks so there is a potential for identifying species. Scattered statoliths have been recorded but cannot be linked to a named species. It has been argued that the white discs with hooks could have been suckers, but it is difficult to understand that a sucker with a hook in its centre could function effectively. The Christian Malford beds were re-opened in 2008 by the BGS and a core from the ‘squid bed’ was found to have earbones, or ‘statoliths’, scattered throughout it. There is a need to relate these to a species, so CT scanning of specimens from Christian Malford in the Natural History Museum is taking place to see if this can be achieved. Different shaped hooks are now thought to exist on the same animal, as one specimen from Germany shows five different kinds, and there are interesting questions on the evolution of the hooks that we see in the geological record.
An ichthyosaur specimen in the Etches Collection appears to show hooks as stomach contents, but it is possible that these may have fallen onto the specimen after death.
The exceptional preservation of material is exciting and there is plenty more research to be done. Recently new specimens have been found and cleaned, clearly showing the arrangement of hooks in the arms. An old specimen, from the BGS collections, has been shown to record the capture, and presumed feeding, of a squid-like cephalopod holding a fish (Dorsetichthys bechei); one of the earliest records of cephalopod predation.
The published paper at The Geologists Association is:
M.B. Hart, et al., Life and death in the Jurassic seas of Dorset, Southern England, Proc. Geol. Assoc. (2020)
is online at https://doi.org/10.1016/j.pgeola.2020.03.009
and available as a PDF download from this website here
For that paper this is the Abstract: The Jurassic succession of the Wessex Basin, especially that cropping out along the Dorset Coast, contains important Lagerstätten for coleoid cephalopods. The Blue Lias and Charmouth Mudstone formations have, since the nineteenth century, provided large numbers of important body fossils that inform our knowledge of coleoid palaeontology. In many of these mudstones specimens of palaeobiological significance have been found, especially those with the arms and hooks with which the living animals caught their prey. This is particularly true in the case of a specimen of Clarkeiteuthis sp. cf. C. montefiorei (Buckman,1879) found in the nineteenth century with a fish in its jaws and which appears to have caused the death, and subsequent preservation, of both animals. © 2020 The Geologists’ Association. Published by Elsevier Ltd. All rights reserved
Following ‘official’ retirement from the University of Plymouth in 2010, Malcolm is now Emeritus Professor of Micropalaeontology. He graduated with a degree in Geology at Imperial College (London) in 1966 and remained in the college to undertake PhD research. Having worked weekends in the Channel Tunnel Laboratory in Dover Castle during 1965/66, his research was to extend work on the Lower Chalk westwards to Southern and South-West England. His first teaching post was as a Junior Lecturer at the University of Newcastle; returning to his birthplace in Northumberland. In 1972, with the potential closure of the Department being considered, he moved to Plymouth Polytechnic and has remained in the South-West since that time. Over the years, up to retirement, he has been Research Coordinator, Head of Department of Geological Sciences, Pro Vice-Chancellor (Research), and – finally – associate Dean of Research in the Faculty of Science. Author of ~270 research papers and an editor of several books (including the definitive work on the Channel Tunnel), Malcolm has supervised 37 PhD students and undertaken research all around the world (and in the world’s oceans). In 1983 he was shipboard micropalaeontologist on the Glomar Challenger, drilling a series of cores in the Bermuda Triangle! He is still an active member of several learned societies and is currently Editor-in-Chief of the Proceedings of the Geologists’ Association, as well as being Editor of Geoscience in South-West England and the Transactions of the Devonshire Association.
Keywords: Lower Jurassic, Clarkeiteuthis, Diplobelida, Cephalopoda, Predation, Taphonomy
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