Cephalopods are extraordinary molluscs equipped with vertebrate-like intelligence and a unique buoyancy system for locomotion. A growing body of evidence from the fossil record, embryology and Bayesian molecular divergence estimations provides a comprehensive picture of their origins and evolution. Cephalopods evolved during the Cambrian (∼530 Ma) from a monoplacophoran-like mollusc in which the conical, external shell was modified into a chambered buoyancy apparatus. During the mid-Palaeozoic (∼416 Ma) cephalopods diverged into nautiloids and the presently dominant coleoids. Coleoids (i.e. squids, cuttlefish and octopods) internalised their shells and, in the late Palaeozoic (∼276 Ma), diverged into Vampyropoda and the Decabrachia. This shell internalisation appears to be a unique evolutionary event. In contrast, the loss of a mineralised shell has occurred several times in distinct coleoid lineages. The general tendency of shell reduction reflects a trend towards active modes of life and much more complex behaviour.

Cephalopod origin and evolution: A congruent picture emerging from fossils, development and molecules: Extant cephalopods are younger than previously realised and were under major selection to become agile, shell-less predators.

Chapter 22 – The Devonian Period

Ammonites are prominent in macroevolutionary studies because of their abundance and diversity in the fossil record, but their paleobiology and position in the marine food web are not well understood due to the lack of preserved soft tissue. We present three-dimensional reconstructions of the buccal apparatus in the Mesozoic ammonite Baculites with the use of synchrotron x-ray microtomography. Buccal mass morphology, combined with the coexistence of food remains found in the buccal mass, suggests that these ammonites fed on plankton. This diet may have extended to all aptychophoran ammonites, which share the same buccal mass morphology. Understanding the role of these ammonites in the Mesozoic food web provides insights into their radiation in the Early Jurassic, as well as their extinction at the end of the Cretaceous/early Paleogene.

https://science.sciencemag.org/content/sci/331/6013/70.full.pdf

The Role of Ammonites in the Mesozoic Marine Food Web Revealed by Jaw Preservation

Structural biological materials such as bone, teeth or mollusk shells draw their remarkable performance from a sophisticated interplay of architectures and weak interfaces. Pushed to the extreme, this concept leads to sutured materials, which contain thin lines with complex geometries. Sutured materials are prominent in nature, and have recently served as bioinspiration for toughened ceramics and glasses. Sutures can generate large deformations, toughness and damping in otherwise all brittle systems and materials. In this study we examine the design and optimization of sutures with a jigsaw puzzle-like geometry, focusing on the non-linear traction behavior generated by the frictional pullout of the jigsaw tabs. We present analytical models which accurately predict the entire pullout response. Pullout strength and energy absorption increase with higher interlocking angles and for higher coefficients of friction, but the associated high stresses in the solid may fracture the tabs. Systematic optimization reveals a counter-intuitive result: the best pullout performance is achieved with interfaces with low coefficient of friction and high interlocking angle. We finally use 3D printing and mechanical testing to verify the accuracy of the models and of the optimization. The models and guidelines we present here can be extended to other types of geometries and sutured materials subjected to other loading/boundary conditions. The nonlinear responses of sutures are particularly attractive to augment the properties and functionalities of inherently brittle materials such as ceramics and glasses.

Bio-inspired “jigsaw”-like interlocking sutures: Modeling, optimization, 3D printing and testing

The first DNA sequence of a cephalopod was published in 1983 and the first molecular paper focusing on cephalopods was published in 1994. In this review we trace progress in the field. We examine the placement of Cephalopoda with respect to other molluscan classes and we examine relationships within Cephalopoda. We provide a summary tree of the relationships between cephalopod orders and we examine relationships of taxa within each of these orders. Although much knowledge has been gained over the past 20 years, deeper-level relationships are still not well understood and there is still much scope for further research in this field. Genomic studies are likely to contribute significantly to our knowledge in the future.

/pdf/the-contribution-of-molecular-data-to-our-understanding-of-3bbk1wy3ak.pdf

The contribution of molecular data to our understanding of cephalopod evolution and systematics: a review

Part I: Phylogeny and Systematics 1. Phylogenetic Practices among Scholars of Fossil Cephalopods, with Special Reference to Cladistics Pascal Neige, Isabelle Rouget, and Sebastien Moyne 2. Patterns of Embryonic Development in Early to Middle Devonian Ammonoids Susan M. Klofak, Neil H. Landman, and Royal H. Mapes 3. Mode of Life of the Frasnian (Late Devonian) Ammonoid Manticoceras from Coumiac (Montagne Noire, France) Dieter Korn and Christian Klug 4. GONIAT - The Current State of the Paleontological Database System on Paleozoic Ammonoids Jurgen Kullmann 5. Ornamental polymorphism in Placenticeras kaffrarium (Ammonoidea Upper Cretaceous of India): Evolutionary implications Tapas K. Gangopadhyay and Subhendu Bardhan 6. A Late Carboniferous Coleoid Cephalopod from the Mazon Creek Lagerstatte (USA), with a Radula, Arm Hooks, Mantle Tissues, and Ink Larisa A. Doguzhaeva, Royal H. Mapes, and Harry Mutvei 7. On the Species Status of Spirula spirula (Linne, 1758) (Cephalopoda): A New Approach Based on Divergence of Amino Acid Sequences between the Canaries and New Caledonia Kerstin Warnke Part II: Morphology of Soft and Hard Tissues 8. Understanding Ammonoid Sutures: New Insight into the Dynamic Evolution of Paleozoic Suture Morphology Emily G. Allen 9. Cameral Membranes in Carboniferous and Permian Goniatites: Description and Relationship to Pseudosutures Kristin Polizzotto, Neil H. Landman, and Royal H. Mapes 10. Soft-Tissue Attachment of Middle Triassic Ceratitida from Germany Christian Klug, Michael Montenari, Hartmut Schulz, and Max Urlichs 11. The Preservation of Body Tissues, Shell, and Mandibles in the Ceratitid AmmonoidAustrotrachyceras (Late Triassic), Austria Larisa A. Doguzhaeva, Royal H. Mapes, Herbert Summesberger, and Harry Mutvei 12. Connecting Ring Ultrastructure in the Jurassic Ammonoid Quenstedtoceras with Discussion on Mode of Life of Ammonoids Harry Mutvei and Elena Dunca 13. Jaws and Radula of Baculites from the Upper Cretaceous (Campanian) of North America Neil H. Landman, Neal L. Larson, and William A. Cobban 14 Ultrastructure Analyses on the Conotheca of the Genus Belemnotheutis (Belemnitida: Coleoidea) Dirk Fuchs, Helmut Keupp, Vasilij Mitta, and Theo Engeser Part III: Biogeography, Biostratigraphy, Ecology, and Taphonomy 15. New Data on the Clymeniid Faunas of the Urals and Kazakhstan Svetlana Nikolaeva 16. Deformities in the Late Callovian (Late Middle Jurassic) Ammonite Fauna from Saratov, Russia Neal L. Larson 17. Biogeography of Kutch Ammonites During the Latest Jurassic (Tithonian) and a Global Paleobiogeographic Overview Subhendu Bardhan, Sabyasachi Shome, and Pinaki Roy 18: Ammonite Touch Marks in Upper Cretaceous (Cenomanian-Santonian) Deposits of the Western Interior Seaway Neil H. Landman and William A. Cobban 19: Some Data on the Distribution and Biology of the Boreal Clubhook Squid Moroteuthis robusta (Verrill, 1876) (Onychoteuthidae, Teuthida) in the Northwest Pacific Alexei M. Orlov 20: Habitat Ecology of Enteroctopus dofleini from Middens and Live Prey Surveys in Prince William Sound, Alaska D. Scheel, A. Lauster, and T.L.S. Vincent

Cephalopods present and past : new insights and fresh perspectives

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Cephalopods present and past : new insights and fresh perspectives