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The extinct marine megafauna of the Phanerozoic
- Catalina Pimiento, Kristína Kocáková, Gregor H. Mathes, Thodoris Argyriou, Edwin-Alberto Cadena, Jack A. Cooper, Dirley Cortés, Daniel J. Field, Christian Klug, Torsten M. Scheyer, Ana M. Valenzuela-Toro, Timon Buess, Meike Günter, Amanda M. Gardiner, Pascale Hatt, Geraldine Holdener, Giulia Jacober, Sabrina Kobelt, Sheldon Masseraz, Ian Mehli, Sarah Reiff, Eva Rigendinger, Mimo Ruckstuhl, Santana Schneider, Clarissa Seige, Nathalie Senn, Valeria Staccoli, Jessica Baumann, Livio Flüeler, Lino J. Guevara, Esin Ickin, Kimberley C. Kissling, Janis Rogenmoser, Dominik Spitznagel, Jaime A. Villafaña, Chiara Zanatta
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- Journal:
- Cambridge Prisms: Extinction / Volume 2 / 2024
- Published online by Cambridge University Press:
- 17 May 2024, e7
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The modern marine megafauna is known to play important ecological roles and includes many charismatic species that have drawn the attention of both the scientific community and the public. However, the extinct marine megafauna has never been assessed as a whole, nor has it been defined in deep time. Here, we review the literature to define and list the species that constitute the extinct marine megafauna, and to explore biological and ecological patterns throughout the Phanerozoic. We propose a size cut-off of 1 m of length to define the extinct marine megafauna. Based on this definition, we list 706 taxa belonging to eight main groups. We found that the extinct marine megafauna was conspicuous over the Phanerozoic and ubiquitous across all geological eras and periods, with the Mesozoic, especially the Cretaceous, having the greatest number of taxa. Marine reptiles include the largest size recorded (21 m; Shonisaurus sikanniensis) and contain the highest number of extinct marine megafaunal taxa. This contrasts with today’s assemblage, where marine animals achieve sizes of >30 m. The extinct marine megafaunal taxa were found to be well-represented in the Paleobiology Database, but not better sampled than their smaller counterparts. Among the extinct marine megafauna, there appears to be an overall increase in body size through time. Most extinct megafaunal taxa were inferred to be macropredators preferentially living in coastal environments. Across the Phanerozoic, megafaunal species had similar extinction risks as smaller species, in stark contrast to modern oceans where the large species are most affected by human perturbations. Our work represents a first step towards a better understanding of the marine megafauna that lived in the geological past. However, more work is required to expand our list of taxa and their traits so that we can obtain a more complete picture of their ecology and evolution.
Prescreening Hydraulic Lime-Binders for Disordered Calcite in Caesarea Maritima: Characterizing the Chemical Environment Using FTIR
- Yotam Asscher, Aliza van Zuiden, Chen Elimelech, Peter Gendelman, Uzi ‘Ad, Jacob Sharvit, Michele Secco, Giulia Ricci, Gilberto Artioli
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- Journal:
- Radiocarbon / Volume 62 / Issue 3 / June 2020
- Published online by Cambridge University Press:
- 20 April 2020, pp. 527-543
- Print publication:
- June 2020
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Hydraulic lime binders are considered a technological marvel which revolutionized construction techniques in antiquity. The core material is made of a binder that is a mixture of calcite and hydraulic phases, which are amorphous silicate compounds that nanostructurally polymerize into insoluble phases that harden even underwater, formed during the reaction between lime and reactive silicates such as volcanic ash. This is also what makes hydraulic lime so hard to radiocarbon (14C) date. These insoluble phases contain carbonates that may set centuries following their application, resulting in younger ages, which may contaminate the calcite fraction that is favorable for 14C dating. This calcite fraction forms upon the incorporation of atmospheric carbon dioxide during the setting of the hydrated lime. Therefore, different characterization methods are being constantly developed for identifying and characterizing the components of hydraulic lime-binders. In this work, we present a rapid characterization technique based on Fourier transform infrared spectroscopy (FTIR) that characterizes the atomic disorder and chemical environment of the carbonates and silicates fractions in the binder. The atomic disorder of the calcite crystallites was determined by the ν2 and ν4 vibrational modes, and the silicates were characterized by the main peak asymmetry and full width at half maximum (FWHM). Different hydraulic binders from Caesarea Maritima were examined, including Herodian mortars from the underwater breakwater and on-land plasters and mortars from the portʼs warehouse and vaults. Hydraulic binders, in which the calcite fraction in the binder shows atomic disorder that is comparable to modern plaster binders, was associated with silicates that have asymmetry and FWHM of clays and quartz. These materials are considered to be in good preservation state for 14C dating since their carbonates crystallites are disordered and did not interact with the environment chemically to form stable and ordered crystals. Interestingly, the atomic disorder of binders that underwent chemical alterations and recrystallization processes, are associated with reactive silicates aggregates such as volcanic ash (pozzolana). These results suggest a new way to prescreen materials for radiocarbon dating based on the composition of lime-binders and preservation state of the carbonate fraction and hydraulic products.