Uneven spatial sampling distorts reconstructions of Phanerozoic seawater temperature

Paleotemperature proxy records are widely used to reconstruct the global climate throughout the Phanerozoic and to test macroevolutionary hypotheses. However, the spatial distribution of these records varies through time. This is problematic because heat is unevenly distributed across Earth's surface. Consequently, heterogeneous spatial sampling of proxy data has the potential to bias reconstructed temperature curves. We evaluated the spatiotemporal evolution of sampling using a compilation of Phanerozoic δ18O data. We tested the influence of variable spatial coverage on global estimates of paleotemperature by sampling a steep “modern-type” latitudinal temperature gradient and a flattened “Eocene-type” gradient, based on the spatial distribution of δ18O samples. We show that global paleotemperature is overestimated in ∼70% of Phanerozoic stages. Perceived climatic trends for some intervals might be artifactually induced by shifts in paleolatitudinal sampling, with equatorward shifts in sampling concurring with warming trends, and poleward shifts concurring with cooling trends. Yet, the magnitude of some climatic perturbations might also be underestimated. For example, the observed Ordovician cooling trend may be underestimated due to an equatorward shift in sampling. Our findings suggest that while proxy records are vital for reconstructing Earth's paleotemperature in deep time, consideration of the spatial nature of these data is crucial to improving these reconstructions

Maximum rates of climate change are systematically underestimated in the geological record

D.B.K. was supported by NERC Fellowship grant NE/I02089X/1 and W.K. by DFG grant Ki 806/12-1. Jonny Beedell is thanked for his help in data compilation and Michael Joachimski for discussions.Peer reviewedPublisher PD

palaeoverse: A community‐driven R package to support palaeobiological analysis

1. The open-source programming language ‘R' has become a standard tool in the palaeobiologist's toolkit. Its popularity within the palaeobiological community continues to grow, with published articles increasingly citing the usage of R and R packages. However, there are currently a lack of agreed standards for data preparation and available frameworks to support the implementation of such standards. Consequently, data preparation workflows are often unclear and not reproducible, even when code is provided. Moreover, due to a lack of code accessibility and documentation, palaeobiologists are often forced to ‘reinvent the wheel’ to find solutions to issues already solved by other members of the community. 2. Here, we introduce palaeoverse, a community-driven R package to aid data preparation and exploration for quantitative palaeobiological research. The package is freely available and has three core principles: (1) streamline data preparation and analyses; (2) enhance code readability; and (3) improve reproducibility of results. To develop these aims, we assessed the analytical needs of the broader palaeobiological community using an online survey, in addition to incorporating our own experiences. 3. In this work, we first report the findings of the survey, which shaped the development of the package. Subsequently, we describe and demonstrate the functionality available in palaeoverse and provide usage examples. Finally, we discuss the resources we have made available for the community and our future plans for the broader Palaeoverse project. 4. palaeoverse is a community-driven R package for palaeobiology, developed with the intention of bringing palaeobiologists together to establish agreed standards for high-quality quantitative research. The package provides a user-friendly platform for preparing data for analysis with well-documented open-source code to enhance transparency. The functionality available in palaeoverse improves code reproducibility and accessibility, which is beneficial for both the review process and future research

Environmental controls on the skeletal mineralogy of marine calcifiers

Parts of the thesis have been published in: Eichenseer, K., Balthasar, U., Smart, C. W., Stander, J., Haaga, K. A., & Kiessling, W. (2019). Jurassic shift from abiotic to biotic control on marine ecological success. Nature Geoscience, 12(8), 638-642. https://doi.org/10.1038/s41561-019-0392-9 PEARL: http://hdl.handle.net/10026.1/14472Calcifying organisms secrete skeletons consisting of calcium carbonate (CaCO3). The two principle CaCO3 polymorphs used by marine calcifiers are aragonite and calcite. In the abiotic precipitation of CaCO3, the Mg/Ca ratio and the temperature are established controls of polymorph formation, but the importance of other factors, for example salinity, remains uncertain. The first objective of this thesis was to clarify the role of salinity in abiotic CaCO3 precipitation (Chapter 2). Experiments at salinities of 20, 35 and 50 and a Mg/Ca ratio of 2 resulted in co-precipitation of aragonite and calcite in all experiments, and no significant salinity influence on overall polymorph formation could be deduced. The average growth of individual calcite crystals was reduced, however, in the low-salinity setup. Although the skeletal mineralogy of calcifiers is generally tied to their phylogenetic history, the skeletal mineralogy, growth rates and skeletal production of many calcifying taxa are affected by the ambient Mg/Ca ratio, temperature and salinity. To test whether environmental factors shape the distribution of modern calcifiers with regards to their skeletal mineralogy, epifaunal bivalve occurrences from the Ocean Biodiversity Information System (OBIS) were related local temperatures and salinities (Chapter 3). Bimineralic bivalve species had higher temperature ranges, on average, than purely aragonitic bivalves, and bimineralic bivalves occurred more often in regions of high annual temperature variability. By adjusting the relative amount of aragonite and calcite secretion, bimineralic bivalves may be able to endure a greater range of environmental conditions. Additionally, bimineralic occurrences were associated with lower temperatures and lower salinities, matching with observations of increased calcite proportions in Mytilus shells under these conditions. Recent improvements in the understanding of how the Mg/Ca ratio and temperature combine to control CaCO3 polymorph formation have allowed to create an Ordovician – Pleistocene curve of aragonite or calcite favouring conditions, termed “aragonite sea intensity” (ASI, Chapter 4). In the Ordovician – Middle Jurassic, ASI was correlated with the relative success of aragonitic calcifiers from the Paleobiology Database (PBDB), as well as with the relative production of aragonite in reefs from the Paleoreefs Database (PARED). From the Late Jurassic onwards, temporal trends in marine skeletal mineralogy appeared unaffected by changes in ASI, demonstrating a decoupling of aragonite-calcite sea conditions and the evolutionary success of marine calcifiers. The onset of the modern carbon cycle and the resulting ocean buffering, along with rising metabolic rates may explain why marine calcifiers were less susceptible to changes in the abiotic environment after the mid-Mesozoic (Chapter 5). However, latitudinal and depth trends in skeletal mineralogy within stages persisted after the Jurassic (Chapter 4), indicating, together with the results of Chapter 3, that aragonite-calcite sea conditions still influence the distribution of modern marine calcifiers

palaeoverse: A community‐driven R package to support palaeobiological analysis

Abstract The open‐source programming language ‘R' has become a standard tool in the palaeobiologist's toolkit. Its popularity within the palaeobiological community continues to grow, with published articles increasingly citing the usage of R and R packages. However, there are currently a lack of agreed standards for data preparation and available frameworks to support the implementation of such standards. Consequently, data preparation workflows are often unclear and not reproducible, even when code is provided. Moreover, due to a lack of code accessibility and documentation, palaeobiologists are often forced to ‘reinvent the wheel’ to find solutions to issues already solved by other members of the community. Here, we introduce palaeoverse, a community‐driven R package to aid data preparation and exploration for quantitative palaeobiological research. The package is freely available and has three core principles: (1) streamline data preparation and analyses; (2) enhance code readability; and (3) improve reproducibility of results. To develop these aims, we assessed the analytical needs of the broader palaeobiological community using an online survey, in addition to incorporating our own experiences. In this work, we first report the findings of the survey, which shaped the development of the package. Subsequently, we describe and demonstrate the functionality available in palaeoverse and provide usage examples. Finally, we discuss the resources we have made available for the community and our future plans for the broader Palaeoverse project. palaeoverse is a community‐driven R package for palaeobiology, developed with the intention of bringing palaeobiologists together to establish agreed standards for high‐quality quantitative research. The package provides a user‐friendly platform for preparing data for analysis with well‐documented open‐source code to enhance transparency. The functionality available in palaeoverse improves code reproducibility and accessibility, which is beneficial for both the review process and future research