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Article: Buoyancy mechanisms limit preservation of coleoid cephalopod soft tissues in Mesozoic Lagerstätten

Palaeontology Cover Image - Volume 60 Part 1
Publication: Palaeontology
Volume: 60
Part: 1
Publication Date: January 2017
Page(s): 1 14
Author(s): Thomas Clements, Caitlin Colleary, Kenneth De Baets, and Jakob Vinther
Addition Information

How to Cite

CLEMENTS, T., COLLEARY, C., DE BAETS, K., VINTHER, J. 2017. Buoyancy mechanisms limit preservation of coleoid cephalopod soft tissues in Mesozoic Lagerstätten. Palaeontology, 60, 1, 1-14. DOI: 10.1111/pala.12267

Author Information

  • Thomas Clements - School of Earth Sciences Bristol UK (Email: tc195@le.ac.uk)
  • Caitlin Colleary - School of Earth Sciences Bristol UK
  • Kenneth De Baets - School of Earth Sciences Bristol UK
  • Jakob Vinther - School of Earth Sciences Bristol UK (Email: jakob.vinther@bristol.ac.uk)

Publication History

  • Manuscript Accepted: 14 September 2016
  • Manuscript Received: 26 July 2016

Funded By

Natural Environment Research Council. Grant Number: P14DF19

Online Version Hosted By

Wiley Online Library (Open Access)
Get Article: Wiley Online Library [Open Access]

Abstract

Coleoid cephalopods are characterized by internalization of their shell, and are divided into the ten‐armed Decabrachia (squids and cuttlefish) and the eight‐armed Vampyropoda (octopuses and vampire squid). They have a rich fossil record predominantly of the limited biomineralized skeletal elements they possess: arm hooks, statoliths, mouthparts (the buccal mass) and internal shell (gladius or pen), although exquisitely preserved soft tissue coleoids are known from several Lagerstätten worldwide. Recent studies have shown that although morphological similarities between extant decabrachian gladii and fossil examples exist, no known examples of fossil decabrachians are currently known. However, molecular clock data and phylogenetic bracketing suggest that they should be present in Lagerstätten that are rich in vampyropod soft tissue fossils (i.e. Hâkel and Hâdjoula Lagerstätten, Cretaceous, Lebanon). We propose that a hitherto unknown taphonomic bias pertaining to the differing methods of buoyancy control within coleoid groups limits preservation potential. Both negatively and neutrally buoyant decabrachians use chemical buoyancy control (ammonia) whereas vampyropods do not. In the event of rapid burial in an environment conducive to exceptional preservation, ammonia dramatically decreases the ability of the decabrachian carcass to generate the required pH for authigenic calcium phosphate replacement, limiting its preservation potential. Moreover, the greater surface area and comparatively fragile dermis further decrease the potential for fossilization. This taphonomic bias may have contributed to the lack of preserved labile soft‐tissues in other cephalopods groups such as the ammonoids.

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