Alma Mater Studiorum – Università di Bologna DOTTORATO DI RICERCA IN SCIENZE DELLA TERRA DELLA VITA E DELL’AMBIENTE Ciclo XXXI Settore concorsuale: 04/A2 Settore Scientifico disciplinare: GEO/01 Stratigraphic paleobiology of late Quaternary mollusk assemblages from the Po Plain-Adriatic Sea system Presentata da: Michele Azzarone Coordinatore Dottorato: Supervisore: Prof. Giulio Viola Dott.Daniele Scarponi Esame Finale anno 2019 Abstract Stratigraphic paleobiology - a relatively new approach for investigating fossiliferous sedimentary successions - is rooted on the assumption that the fossil record cannot be read at face value, being controlled not only by biotic, but also by sedimentary processes that control deposition and erosion of sediments. By applying the stratigraphic paleobiology tenets, this Ph.D. project focused on acquisition and analyses of macrofossils data to assess the response of late Quaternary ecosystems to environmental changes and enhance stratigraphic interpretations of fossiliferous successions. A primary activity of my Ph.D. research involved assembling a macrobenthic dataset from the latest Pleistocene glacial succession of the near-Mid Adriatic Deep (Central Adriatic, Italy). This dataset once combined with its counterpart from the Po coastal plain (Holocene), will offer a unique perspective on mollusk faunas and their dynamics during the current glacial-interglacial cycle. This thesis includes four papers. The first one assessed the quality and resolution of the macrofossil record from transgressive Holocene deposits of Po plain (Italy). The second paper focused on the Holocene fossil record of the Po coastal plain to evaluate the response of trematode parasites to high-frequency sea-level oscillations. The third study investigated distribution of last occurrences of macrobenthic species along a down-dip transect in the Po coastal plain and evaluate potential effects of sequence stratigraphic architecture on mass extinction pattern. The fourth is a case study to test the robustness of the paleoecological pattern derived by the application of different ordination analyses (DCA and nMDS) and to assess the main environmental driver(s) of faunal turnover in marine settings. In summary, my Ph.D. demonstrates that even if the fossil record cannot always be read literally, the stratigraphic paleobiology approach to the geologic record makes it possible to interpret biological trends from the fossil record and enhance the stratigraphic resolution of fossiliferous successions. Index 1. Introduction ........................................................................................................ 6 1.1. The Quaternary fossil record: an ideal laboratory for stratigraphic paleobiology................ 7 1.2. Mollusk fauna as a tool for stratigraphic paleobiology ......................................................... 8 1.3. The Milankovitch and sub-Milankovitch cyclicity ................................................................ 8 2. The Po Plain-Adriatic Sea system ........................................................................ 13 2.1. The Po Delta and its southern coastal plain ........................................................... 15 2.1.1. Tectonic setting ............................................................................................................ 16 2.1.2. Late Quaternary stratigraphic architecture .............................................................. 18 2.2. The Adriatic Sea and the Mid Adriatic Deep (MAD) ............................................. 25 2.2.1. Tectonic setting ............................................................................................................ 26 2.2.2. Late Quaternary stratigraphic architecture ..............................................................2 9 3. Research Outlines .............................................................................................. 34 4. The Mid Adriatic Deep (MAD) dataset ................................................................ 38 4.1. MAD data collection ............................................................................................................3 9 4.2. MAD dataset structure ........................................................................................................ 41 4.3. Future applications and outreach ....................................................................................... 44 5. Manuscript I ...................................................................................................... 46 “Systematic vertical and lateral changes in quality and time resolution of the macrofossil record: Insights from Holocene transgressive deposits, Po coastal plain, Italy” 6. Manuscript II ..................................................................................................... 60 “Surges in trematode prevalence linked to centennial-scale flooding events in the Adriatic” 7. Manuscript III .................................................................................................... 87 “Stratigraphic signatures of mass extinction: ecological and sedimentary determinants” 8. Manuscript IV ................................................................................................... 113 “Early-Middle Pleistocene benthic turnover and oxygen isotope stratigraphy from the Central Mediterranean (Valle di Manche, Crotone Basin, Italy): Data and trends” 9. Concluding remarks .......................................................................................... 129 References .............................................................................................................. 132 “It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes with various insect flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependant on each other in so complex manner, have all been produced by laws acting around us […]. There is a grandeur in this view of life, with several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms, most beautiful and most wonderful have been, and are being, evolved”. Charles Darwin On the Origin of Species Chapter 1 Introduction 6 1. Introduction Since the last few decades, a new approach for investigating fossiliferous sedimentary successions has gained approval throughout the paleontological scientific community. This recent development in the field of paleontology relies on the assumptions that the fossil record cannot be read at face value and that fossil dynamics through time and space are easier to interpret when analyzed in conjunction with their stratigraphic context (e.g., Kidwell, 1993; Holland, 1995, 2000; Scarponi and Kowalewski, 2004; Dominici and Kowalke, 2007; Patzkowsky and Holland, 2012; Terry and Novack, 2015; Danise and Holland, 2017). This relatively new paradigm to the investigation of the fossil record is known as stratigraphic paleobiology (Patzkowsky and Holland, 2012), which is rooted on the postulation that interpretation of the fossil record should also consider a modern understanding of the principles of sediment accumulation (Patzkowsky and Holland, 2012). Indeed, the distribution of fossil taxa in time and space is controlled not only by biotic processes (e.g., taxa niches, taxa evolutionary strategies, extinctions/originations) but also by physical processes that govern where and when fossiliferous sedimentary bodies are deposited and preserved. Teasing apart the effects of these two suites of processes on structuring fossil associations or at least acknowledgement of their conjunct effects, is pivotal for understand and reconstructing the dynamics of environments and their organisms through time. This is the core of stratigraphic paleobiology. Such an integrated approach is intended primarily to augment the potential of paleontological investigations to answer core questions that lays buried in the geological record of the Earth. A clear example on the assessment and magnitude of stratigraphic controls on fossil distribution is provided by Holland (1995). Here the author shows, by means of model data, that previously described paleobiologic patterns concerning mass extinction and evolutionary dynamics may be partly stratigraphic artifacts originating from the stratigraphic architecture of investigated successions. Specifically, the first and last occurrences (FOs and LOs, respectively) of marine fossil taxa cluster within intervals of strong time condensation or along sequence boundaries. This produces a distortion of the real time of appearance or extinction so that in the fossil record, such FOs and LOs will appear to be simultaneous even if they are not. Examples of such stratigraphic forcing on fossil records have been reported for decades (Patzkowsky and Holland, 1999; Holland, 2000; Kidwell and Holland, 2002; Scarponi and Kowalewski, 2007; Holland and Allen, 2008) and have reached full recognition in Patzkowsky and Holland (2012). The authors pointed out that the introduction of sequence stratigraphy concepts, which lead to a better understanding of sedimentary basin dynamics, will help to sort true biological signals from stratigraphic artifacts that shaped the fossil record. The last few years saw a growing wealth of case studies