Paleobiology was founded 50 years ago to provide an outlet for biological paleontology, with an emphasis on investigating evolutionary patterns and processes that could apply generally across the history of life. While the intellectual and financial prospects for Paleobiology were uncertain in the beginning (Sepkoski 2012; Valentine 2009), this 50 th anniversary issue testifies to its overwhelming success. Fifty years of anything well done deserves a celebration. These moments are a time for reflection and a time for imagining future directions. With this introduction, we outline briefly the start of the journal and two landmark anniversary issues, the 10 th and the 25 th . No special issue can adequately survey all research themes in a field as intellectually rich as paleobiology. However, these anniversary issues offer a snapshot of research directions, and they can trace the shift and expansion of established fields and mark the emergence of new ones. We end by outlining the contributions to the 50 th anniversary issue that summarize current themes and future directions for the field.

Stratigraphic paleobiology uses a modern understanding of the construction of the stratigraphic record—from beds to depositional sequences to sedimentary basins—to interpret patterns and guide sampling strategies in the fossil record. Over the past 25 years, its principles have been established primarily through forward numerical modeling, originally in shallow-marine systems and more recently in nonmarine systems. Predictions of these models have been tested through outcrop-scale and basin-scale field studies, which have also revealed new insights. At multi-basin and global scales, understanding the joint development of the biotic and sedimentary records has come largely from macrostratigraphy, the analysis of gap-bound packages of sedimentary rock. Here, we present recent advances in six major areas of stratigraphic paleobiology, including critical tests in the Po Plain of Italy, mass extinctions and recoveries, contrasts of shallow-marine and nonmarine systems, the interrelationships of habitats and stratigraphic architecture, large-scale stratigraphic architecture, and the assembly of regional ecosystems. We highlight the potential for future research that applies stratigraphic paleobiological concepts to studies of climate change, geochemistry, phylogenetics, and the large-scale structure of the fossil record. We conclude with the need for more stratigraphic thinking in paleobiology.

Open AccessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Reddin Carl J., Aberhan Martin, Dimitrijević Danijela, Dowding Elizabeth M., Kocsis Ádám T., Mathes Gregor, Nätscher Paulina S., Patzkowsky Mark E. and Kiessling Wolfgang 2023Oversimplification risks too much: a response to 'How predictable are mass extinction events?'R. Soc. Open Sci.10230400230400http://doi.org/10.1098/rsos.230400SectionOpen AccessCommentOversimplification risks too much: a response to 'How predictable are mass extinction events?' Carl J. Reddin Carl J. Reddin http://orcid.org/0000-0001-5930-1164 Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany [email protected] Contribution: Conceptualization, Writing – original draft, Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author , Martin Aberhan Martin Aberhan https://orcid.org/0000-0002-0364-9695 Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author , Danijela Dimitrijević Danijela Dimitrijević https://orcid.org/0000-0002-1311-0474 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author , Elizabeth M. Dowding Elizabeth M. Dowding http://orcid.org/0000-0002-2423-8254 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author , Ádám T. Kocsis Ádám T. Kocsis http://orcid.org/0000-0002-9028-665X GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author , Gregor Mathes Gregor Mathes http://orcid.org/0000-0002-2788-1173 Paleontological Institute and Museum, University of Zurich, Zurich, Switzerland Contribution: Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author , Paulina S. Nätscher Paulina S. Nätscher http://orcid.org/0000-0001-5121-3055 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author , Mark E. Patzkowsky Mark E. Patzkowsky https://orcid.org/0000-0002-1761-3298 Department of Geosciences, Pennsylvania State University, University Park, PA, USA Contribution: Writing – original draft, Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author and Wolfgang Kiessling Wolfgang Kiessling http://orcid.org/0000-0002-1088-2014 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Conceptualization, Writing – original draft, Writing – review & editing Google Scholar Find this author on PubMed Search for more papers by this author Carl J. Reddin Carl J. Reddin http://orcid.org/0000-0001-5930-1164 Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany [email protected] Contribution: Conceptualization, Writing – original draft, Writing – review & editing Google Scholar Find this author on PubMed , Martin Aberhan Martin Aberhan https://orcid.org/0000-0002-0364-9695 Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed , Danijela Dimitrijević Danijela Dimitrijević https://orcid.org/0000-0002-1311-0474 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed , Elizabeth M. Dowding Elizabeth M. Dowding http://orcid.org/0000-0002-2423-8254 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed , Ádám T. Kocsis Ádám T. Kocsis http://orcid.org/0000-0002-9028-665X GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed , Gregor Mathes Gregor Mathes http://orcid.org/0000-0002-2788-1173 Paleontological Institute and Museum, University of Zurich, Zurich, Switzerland Contribution: Writing – review & editing Google Scholar Find this author on PubMed , Paulina S. Nätscher Paulina S. Nätscher http://orcid.org/0000-0001-5121-3055 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Writing – review & editing Google Scholar Find this author on PubMed , Mark E. Patzkowsky Mark E. Patzkowsky https://orcid.org/0000-0002-1761-3298 Department of Geosciences, Pennsylvania State University, University Park, PA, USA Contribution: Writing – original draft, Writing – review & editing Google Scholar Find this author on PubMed and Wolfgang Kiessling Wolfgang Kiessling http://orcid.org/0000-0002-1088-2014 GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Erlangen, Germany Contribution: Conceptualization, Writing – original draft, Writing – review & editing Google Scholar Find this author on PubMed Published:23 August 2023https://doi.org/10.1098/rsos.230400This article comments on the following:Research ArticleHow predictable are mass extinction events?https://doi.org/10.1098/rsos.221507 William J. Foster, Bethany J. Allen, Niklas H. Kitzmann, Jannes Münchmeyer, Tabea Rettelbach, James D. Witts, Rowan J. Whittle, Ekaterina Larina, Matthew E. Clapham and Alexander M. Dunhill volume 10issue 3Royal Society Open Science15 March 2023 Review history Review history is available via Web of Science at https://www.webofscience.com/api/gateway/wos/peer-review/10.1098/rsos.230400 1. Introduction As anthropogenic climate change pushes modern ecosystems into uncharted territory, marine ectotherms show particularly clear climate change impacts [1,2]. Coincidentally, marine invertebrates have the lion's share of the macrofossil record, sometimes covering ancient episodes of rapid global warming (hyperthermals) that led to extinction crises, including mass extinctions [3]. This makes the fossil record an unrivalled but complex data resource. Foster et al. [4] present a rigorous comparison of three mass extinctions using a trait-based model and machine learning. Their main result, that the impacts of one mass extinction may not be a simple blueprint for the next mass extinction, has implications for the use of fossils to predict future extinction risk. However, we find their main conclusion, that 'extinction selectivity during mass extinctions, therefore, appears to be unpredictable', to be only half of the story and a pessimistic oversimplification of their results. We discuss limitations to their analyses, especially where these highlight exciting avenues and alternative approaches to uncover and improve predictability of biotic crises using palaeobiology [5]. We conclude that the debate over whether the fossil record is a useful information source for extinction risk assessment is only just opening and emerging as a fruitful and urgent area of research. 1.1. Aim for events with modern-relevant drivers Foster et al. [4] focus on three mass extinctions of which only two are thought to have comparable causes and rates of disturbance. Predictability scores between either the End-Permian or End-Triassic models (both hyperthermal events) and the End-Cretaceous (bolide impact) were the lowest among their comparisons [4]. Other studies (e.g. [6]) highlight how the fortunes of physiologically poorly buffered taxa changed from their selective extinction at both the End-Permian and End-Triassic to a selective extinction of physiologically buffered taxa at the End-Cretaceous. Evidence of shared environmental changes [3,7] and selectivity patterns (e.g. [6,8,9]) support shared extinction scenarios: global warming across the End-Permian and End-Triassic versus massive cooling and transient shutdown of primary production due to bolide impact for the End-Cretaceous. Cascading effects may indeed complicate attribution, creating dependences between functional group responses, but should be themselves targeted in future works. 1.2. Sampling heterogeneity Uneven sampling in the fossil record is omnipresent and well known. Observed extinction records are often smeared back in time, more so for some organism groups than others, and the record of each mass extinction varies by the geography of its exposed outcrops (e.g. palaeolatitude) [10–12]. Such 'confounders' in observational data may hide true relationships between features, or create fake ones [13,14]. Different sampling biases might overshadow true ecological similarities, or models may learn to predict shared sampling patterns rather than ecological impacts. Discerning hypothetical ecological signal from noise processes (e.g. sampling bias) is essential to decide the success of a model to predict or associate true ecological impacts (e.g. steps taken in [8]). Machine learning approaches are unfortunately no panacea [14]. 1.3. Phylogenetic covariates Phylogeny remains one of the strongest predictors of extinction [15] and covaries with organism trait grouping focused on by Foster et al. [4]. Groups such as ammonoids and rhynchonelliform brachiopods are generally more at risk of extinction than others [16], which may artificially inflate the importance of some of their traits. Contrasting mono-trait and poly-trait clades may help pick apart this chicken-and-egg puzzle (e.g. [8,15]). 1.4. Performance measurement The benchmark for successful predictability depends on context and discipline. Foster et al. [4] use the standard threshold area under the curve (AUC) ≥ 0.7 as a good or acceptable model. The context needed here is that scores within an event only just meet this mark (AUC = 0.72, 0.72 and 0.8). These values should become the practical benchmark for the best between-event prediction that could be hoped for. If a model trained on random observations of extinction variation at an event struggles to provide a good prediction for extinction variation within the same event, then the conclusion must be that fossil data are difficult to predict from per se. The mean across the six between-event AUC values in Foster et al. [4] was 0.62, which, despite being far below perfect (i.e. AUC = 1), suggests predictable elements to the extinction signature. Identifying the predictable elements of extinction drivers, and the less predictable or less targeted elements (e.g. strongly biased by sampling) is an exciting avenue for future research (e.g. [8,9,17]). 1.5. Use modern ecological understanding to target specific impacts Foster et al. [4] judged predictability based on overall extinction patterns, rather than targeting components hypothesized to be more predictable. Their approach is important given our limited understanding of what drives occurrence variation in the fossil record. However, it neglects the wealth of ecological understanding, which can provide a basis for hypotheses of palaeoecological responses under drivers of interest (e.g. [8,18,19] and references therein). Optimally, cause-effect mechanisms can be modelled to explore agreement between simulated and observed impacts (e.g. [9,17,20]). 1.6. Systems evolve Evolutionary and Earth system changes are components we must account for in hypotheses of cause-effect, as Foster et al. [4] fittingly conclude but do not execute quantitatively. Quantitative appraisal indicates that some invertebrate groups changed their responses to hyperthermals more over time than others (e.g. sponges, organisms with calcitic skeletons), while reefs remain vulnerable [6,8]. This topic needs far more investigation, but evidence can be empirically targeted rather than raised theoretically. 2. Conclusion We congratulate Foster et al. [4] on a sophisticated analysis that explores limits to the predictability we can expect from correlative models derived from the fossil record of mass extinctions. Armed with an ecological understanding of cause-effect mechanisms and their context-dependency [17,19], alongside a respect for biases in the fossil record [10,21] and the limitations of statistical models, we can be better informed when we cautiously approach the fossil record for hints at future perils. This is especially pressing in anticipation of a future mass extinction [22], and there are sufficient commonalities among warming-driven extinction events to state that the past is key to the future [5]. The fossil record of ancient crises, including mass extinctions, is an important, unique, but complex resource for developing our predictive capabilities. Oversimplifying its interpretation will only hinder this goal. Data accessibility No data are associated with this manuscript. Declaration of AI use We have not used AI-assisted technologies in creating this article. Authors' contributions C.J.R. and W.K.: conceptualization, writing—original draft, writing—review and editing; M.A., D.D., E.M.D., Á.T.K., G.M. and P.S.N.: writing—review and editing; M.E.P.: writing—original draft, writing—review and editing. All authors gave final approval for publication and agreed to be held accountable for the work performed therein. Conflict of interest declaration We declare we have no competing interests. Funding This work was supported by the Deutsche Forschungsgemeinschaft (grant nos. AB 109/11-1, BA 5148/1-2, KI 806/17-1, Ko 5382/2-1 and STE 2360/2-1/FOR 2332: Temperature-related stressors as a unifying principle in ancient extinctions), Palaeosynthesis Project, funded through the Volkswagen Institute. Acknowledgements We are grateful for comments from Peter Roopnarine and two anonymous reviewers, and from Rachel Warnock on an earlier version of the manuscript. Footnotes © 2023 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.References1. Pinsky ML, Eikeset AM, McCauley DJ, Payne JL, Sunday JM. 2019 Greater vulnerability to warming of marine versus terrestrial ectotherms. Nature 569, 108-111. (doi:10.1038/s41586-019-1132-4) Crossref, PubMed, ISI, Google Scholar2. Bindoff NL et al. 2019 Changing ocean, marine ecosystems, and dependent communities. In IPCC special report on the ocean and cryosphere in a changing climate, pp. 477-587. Geneva, Switzerland: IPCC. Google Scholar3. Foster GL, Hull P, Lunt DJ, Zachos JC. 2018 Placing our current 'hyperthermal' in the context of rapid climate change in our geological past. Phil. Trans. R. Soc. A 376, 20170086. (doi:10.1098/rsta.2017.0086) Link, ISI, Google Scholar4. Foster WJ et al. 2023 How predictable are mass extinction events? R. Soc. 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Barnosky AD et al. 2011 Has the Earth's sixth mass extinction already arrived? Nature 471, 51-57. (doi:10.1038/nature09678) Crossref, PubMed, ISI, Google Scholar Comments Please enable JavaScript to view the comments powered by Disqus. Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesHow predictable are mass extinction events?15 March 2023Royal Society Open Science This IssueAugust 2023Volume 10Issue 8 Article InformationPubMed:37621666Published by:Royal SocietyOnline ISSN:2054-5703History: Manuscript received29/03/2023Manuscript accepted04/08/2023Published online23/08/2023 License:© 2023 The Authors.Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. Citations and impact Subjectspalaeontology

A bolide impact ∼66 million years ago near Chicxulub, Yucatan Peninsula, Mexico triggered environmental perturbations on a global scale, leading to a mass extinction at the Cretaceous-Paleogene (K-Pg) boundary. Outcrops on the U.S Gulf Coastal Plain that contain the K-Pg boundary provide a detailed record of environments across this critical transition, but questions remain about the nature and timing of depositional processes that affected the region at the time of impact and mass extinction. We present a new study of coarse-grained K-Pg ‘event deposits’ located at the contact between the fossiliferous Cretaceous Corsicana Formation and the Danian Kincaid Formation, and which outcrop in tributaries along the Brazos River, Falls County, Texas. A generalized succession can be recognized in these deposits. We sampled the basal-most unconsolidated units, Unit I and Unit II, and the Corsicana Formation for macrofaunal and sedimentological data. Unit I is interpreted as a debrite, deposited by a medium – high strength cohesive debris flow initiated by ground shaking and intense seismic activity after the Chicxulub impact. Macrofossil analysis shows a mostly locally derived assemblage. Grain size analysis of non‑carbonate portions of the matrix indicates an identical mean grain size to that of the underlying Corsicana Formation. The chaotic fabric, boulder sized clasts, and muddy matrix support the interpretation of deposition via cohesive debris flow. Unit II is also interpreted as a debrite, deposited by a low-medium strength cohesive debris flow. We propose that this unit was initiated by wave energy from a tsunami or local shelf collapse immediately following impact. Macrofossil analysis of Unit II shows an increase in fauna with a predatory/carnivorous lifestyle, which are interpreted as allochthonous elements derived from shoreward environments and transported across the shelf. The high mud content of the matrix and abrupt pinching out on topographic highs support the interpretation of deposition via a cohesive debris flow for Unit II. Our results indicate that sediment flows were a major driver of mass sediment transport in proximal locations directly following the Chicxulub impact.

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Evolutionary and taphonomic implications

We employ modified tip-dating methods to date divergence times within the Strophomenoidea, one of the most abundant and species-rich brachiopod clades to radiate during the Great Ordovician Biodiversification Event (GOBE), to determine if significant environmental changes at this time correlate with the diversification of the clade. Models using origination, extinction and sampling rates to estimate prior probabilities of divergence times strongly support both high rates of anatomical change per million years and rapid divergences shortly before the clade first appears in the fossil record. These divergence times indicate much higher rates of cladogenesis than are typical of brachiopods during this interval. The correspondence of high speciation rates and high anatomical disparity suggests punctuated (speciational) change drove the high frequencies of early anatomical change, which in turn suggests increased ecological opportunities rather than shifting developmental constraints account for high rates of anatomical change. The pulse of rapid evolution began coincident with cooling temperatures, the start of major oscillations in sea level and increased levels of atmospheric oxygen. Our results suggest that these factors permitted major geographical and ecological expansion of strophomenoids with intervals of geographical isolation, resulting in elevated speciation rates and corresponding elevated frequencies of punctuated change.

A fundamental question in paleobiology is whether ecology is correlated with evolutionary history. By combining time-calibrated phylogenetic trees with genus occurrence data through time, we can understand how environmental preferences are distributed on a tree and evaluate support for models of ecological similarity. Exploring parameters that lend support to each evolutionary model will help address questions that lie at the nexus of the evolutionary and ecological sciences. We calculated ecological difference and phylogenetic distance between species pairs for 83 taxa used in recent phylogenetic revisions of the brachiopod order Strophomenida. Ecological difference was calculated as the pairwise distance along gradients of water depth, carbonate, and latitudinal affinity. Phylogenetic distance was calculated as the pairwise branch length between tips of the tree. Our results show no relationship between ecological affinity and phylogeny. Instead results suggest an ecological burst during the initial radiation of the clade. This pattern likely reflects scaling at the largest macroevolutionary and macroecological scales preserved in the fossil record. Hierarchical scaling of ecological and evolutionary processes is complex, but phylogenetic paleoecology is an avenue for better evaluating these questions.

The Late Ordovician mass extinction was an interval of high extinction with inferred low ecological selectivity, resulting in little change in community structure after the event. In contrast, the mass extinction may have fundamentally changed evolutionary dynamics in the surviving groups. We investigated the phylogenetic relationships among strophomenoid brachiopods, a diverse brachiopod superfamily that was a primary component of Ordovician ecosystems. Four Ordovician families/subfamilies sampled in the analysis (Rafinesquinidae, Strophomeninae, Glyptomenidae and Furcitellinae) were reconstructed as monophyletic groups, and the base of the strophomenoid clade that dominated the Silurian recovery was reconstructed as diversifying alongside these families during the Middle Ordovician. We time-calibrated the phylogeny and used geographical occurrences to investigate biogeographical changes in the strophomenoids through time with the R package BiogeoBEARS. Our results indicate that extinction was higher in taxa whose ranges were constrained to tropical or subtropical regions. Furthermore, our results suggest important shifts in the diversification patterns of these brachiopods after the mass extinction. While most of the strophomenoid families survived the Late Ordovician event, ecologically abundant taxonomic groups during the Ordovician were either driven to extinction, reduced in diversity, or slowly died off during the Silurian. The new abundant strophomenoid taxa derived from one clade (consisting of Silurian-Devonian groups such as Douvillinidae, Strophodontidae and Amphistrophiidae) that diversified during the post-extinction radiation. Our results suggest the selective diversification during the Silurian radiation, rather than selective extinction in the Late Ordovician, had a greater impact on the evolutionary history of strophomenoid brachiopods.

Abstract. Mass extinctions affect the history of life by decimating existing diversity and ecological structure and creating new evolutionary and ecological pathways. Both the loss of diversity during these events and the rebound in diversity following extinction had a profound effect on Phanerozoic evolutionary trends. Phylogenetic trees can be used to robustly assess the evolutionary implications of extinction and origination. We examine both extinction and origination during the Late Ordovician mass extinction. This mass extinction was the second largest in terms of taxonomic loss but did not appear to radically alter Paleozoic marine assemblages. We focus on the brachiopod order Strophomenida, whose evolutionary relationships have been recently revised, to explore the disconnect between the processes that drive taxonomic loss and those that restructure ecological communities. Apossible explanation for this disconnect is if extinction and origination were random with respect to morphology. We define morphospace using principal coordinates analysis (PCO) of character data from 61 Ordovician–Devonian taxa and their 45 ancestral nodes, defined by a most parsimonious reconstruction in Mesquite. A bootstrap of the centroid of PCO values indicates that genera were randomly removed from morphospace by the Late Ordovician mass extinction, and new Silurian genera were clustered within a smaller previously unoccupied region of morphospace. Diversification remained morphologically constrained throughout the Silurian and into the Devonian. This suggests that the recovery from the Late Ordovician mass extinction resulted in a long-term shift in strophomenide evolution. More broadly, recovery intervals may hold clues to understanding the evolutionary impact of mass extinctions.