The dynamics of cephalopod assemblages during a period of climate change: a case study of the early Late Ordovician of Baltica

The project will investigate the effects of climate and environmental change on ecosystems using an example from the fossil record - the early Late Ordovician cephalopods from Estonia. The cephalopods were among the top predators of the Ordovician oceans, sensitively reacting to environmental changes. Their hard calcareous shells are often abundant and well-preserved in the Ordovician strata of Baltoscandia. However, the knowledge on cephalopod diversity patterns and composition development is still insufficient there, especially for the early Late Ordovician interval. As a result, the cephalopods are missing from comprehensive palaeoclimatic and palaeoenvironmental analyses. The proposed research aims to fill in this gap by systematic investigation of the distribution, composition and diversity of cephalopods from the Kukruse-Haljala regional stages of Estonia. Morphometric studies and multidimensional statistical methods will be employed to study the response of cephalopods to biotic and abiotic (including climatic) changes assumed or suspected for the Sandbian in Baltica, and to compare the identified patterns at the global scale to discriminate global and regional events. Comparison of the studied cephalopod assemblages with known assemblages from elsewhere (e.g. North America and China) will enable the reconstruction of migration routes and palaeogeographic relationships. The cephalopod data will be integrated with data of an ongoing project of the host institution (PRG1701) on other fossil groups and abiotic parameters. This effort will enhance the understanding of the environments, biotic response to sea level and palaeotemperature changes and elucidate the drivers behind stable isotopic excursions. At the end, the results will be useful for broader palaeoclimatic models and highlight the relevance of deep-time studies for addressing current global climate change and diversity decline.