Space and Time Dynamics

Paleontological data (taxa, traits, occurrences) are unique in that they are centered in both space and geologic time. These data provide essential information on long-term ecological and evolutionary processes, but also on spatial and temporal variations in preservation and so present unique challenges.

The critical need to predict the fate of species in response to current and future climate change has pressed ecologists to explore past species under different climate scenarios to understand a fuller range of environmental controls on ecosystem structure and function. Blois et al. (Reference Blois, Bellvé, Jarzyna, Saupe and Syverson2025) survey the application of environmental niche models (ENMs) to occurrences of fossil species. Using data from fossils introduces unique issues and concerns about data quality, so it is not surprising that most paleoENM studies have been based in the Quaternary, although paleoENMs have been applied to ecosystems as far back as the Ordovician (Stigall Reference Stigall2023). Despite these challenges, paleoENMs have been used in a variety of paleobiogeographic studies to determine range shift through time, infer spatially explicit population dynamics, and evaluate factors responsible for speciation, extinction, and niche change, as well as in conservation paleobiogeography. The authors identify incorporating traits and phylogenetics into paleoENM studies as especially fruitful future directions.

Preservation of soft tissue provides a wealth of information on components of ecosystems that are rarely preserved. For example, exceptional preservation can inform phylogenetic studies with rarely observed character traits, extend the stratigraphic ranges of poorly preserved taxa, and reveal local diversity of taxa usually not preserved. Although these deposits with exceptional preservation, or Lagerstätten, occur in all environments and throughout the geologic column, some types of preservation are restricted to specific intervals of time. Gaines and Droser (Reference Gaines and Droser2025) explore these deposits with a focus on two modes of preservation known only from the Ediacaran and early Cambrian. Ediacaran-type preservation required early lithification of the seafloor by silica cements preserving the Ediacaran assemblages as molds. Burgess Shale–type preservation resulted from early calcite cementation of the seafloor restricting oxidation and microbial activity, thus preserving soft tissues. Early calcite cementation may have been aided by an abundance of kaolinite helping to preserve the soft tissue. The authors argue that the chemical conditions that led to this style of preservation may have also helped to drive diversification by providing nutrients to stimulate productivity and other dissolved compounds to enhance biomineralization.

Many of the frontline questions in paleobiology today, such as the causes and timing of mass extinctions and their recoveries, require knowing how to interpret stratigraphic occurrences of fossils. Stratigraphic paleobiology, the application of modern stratigraphic methods to the study of fossil occurrences, provides this knowledge, and much of the early work in this area appeared in Paleobiology (Jablonski Reference Jablonski1980; Holland Reference Holland1995, Reference Holland, Erwin and Wing2000). Holland et al. (Reference Holland, Patzkowsky and Loughney2025) summarize the developments in this field and outline fruitful new directions. Much of the early work was done in marine systems, but studies in terrestrial deposits are just beginning and show great promise (Holland and Loughney Reference Holland and Loughney2021). Beyond the study of mass extinctions and recovery, stratigraphic paleobiological concepts form the basis for investigation of many other important questions such as the partitioning of diversity in regional ecosystems, the stability of ecological niches, and studies of morphological evolution. New areas where stratigraphic paleobiological approaches are expected to have impact are climate change studies, the interpretation of geochemical proxies related to biotic change, more realistic sampling models for phylogenetic analyses, and assessments of the large-scale structure of the fossil record.

Intrinsic Macroevolutionary Processes

Revisiting multilevel selection in macroevolution, Simpson et al. (Reference Simpson, Halling and Leventhal2025) highlight common misconceptions and provide a way forward. If the average fitness of a group is just the mean of the fitness of its constituents, there would be no place for a selection process to operate differently at different levels, nor would there be the concept of emergent fitness. The authors return to an old idea of “expansion” introduced by Van Valen (Reference Van Valen1973 and other papers). They use it to explain how expansion at one level (like colony size in bryozoans or somatic cell numbers in Volvox colonies) may reflect fitness independent of individual member reproduction. Defining fitness as a vector rather than a particular fixed value is a key contribution of this paper to enhancing macroevolutionary theory.

The role of competition in driving macroevolutionary trends has a long history in paleobiology (Van Valen Reference Van Valen1973; Sepkoski Reference Sepkoski1978, Reference Sepkoski1979). Liow and Quental (Reference Liow and Quental2025) summarize the state of understanding for how interspecies interactions—like competition, predation, and mutualism—can drive diversification, geographic distribution shifts, and trait evolution over time. By reviewing studies of these dynamics, the authors argue that the fossil record uniquely informs long-term evolutionary impacts of such interactions, which are impossible to derive from neontological studies. However, common approaches to establish biotic interactions using the fossil record are deemed inadequate. Liow and Quental (Reference Liow and Quental2025) encourage cross-disciplinary approaches that combine ecological theory, paleontology, and advanced statistical methods to achieve a more holistic view of the interplay of biotic and abiotic factors that shape biodiversity and trait evolution in deep time.

Jablonski and Edie (Reference Jablonski and Edie2025) review the evolutionary consequences of mass extinctions. The authors argue that mass extinctions, while catastrophic in erasing large swaths of taxonomic diversity, often allowed functional diversity to persist. Nevertheless, mass extinctions have substantial macroevolutionary consequences. Global biodiversity will eventually rebound, but in an unprecedented new world such that “recovery” is seen as a misnomer in the context of mass extinctions. The variable postextinction fate of surviving lineages has long been a matter of intense research. Jablonski and Edie (Reference Jablonski and Edie2025) provide a succinct yet comprehensive review of suggested reasons for these possible evolutionary fates, among which what they call “fatal attractors” is perhaps the most promising. “Fatal attractor” refers to the concept that the short-term ecological benefit of some traits may starkly contrast with long-term evolutionary vulnerabilities. A better integration of near-time and deep-time fossil records is the way forward to solve this and similar issues on the variable outcomes of mass extinctions.

Earth–Life Interactions

Kiessling et al. (Reference Kiessling, Reddin, Dowding, Dimitrijević, Raja and Kocsis2025) stress the potential contribution of deep-time paleontological data to understanding climate-induced impacts on the biosphere. Focusing on ancient so-called hyperthermal events, the authors emphasize the need to focus more strongly on effect sizes and uncertainties to inform conservation strategies amid the current climate and biodiversity crises. They also highlight the importance of understanding context and scale dependency in biological responses to climate changes and the interplay of warming, ocean acidification, and deoxygenation as key drivers of past extinctions. The most germane research challenges identified by Kiessling et al. (Reference Kiessling, Reddin, Dowding, Dimitrijević, Raja and Kocsis2025) are (1) the different timescales over which climate impacts are observed today and in the geologic past and (2) the time gap in observed responses between 100 and 10,000 years. Bridging these gaps is key to making deep-time paleontological data more comparable with and thus relevant for modern climate-impact research.

Using elasmobranchs (sharks, rays, and skates) as a model, Dillon and Pimiento (Reference Dillon and Pimiento2025) provide a primer on how paleobiological research can align with conservation priorities. Conservation paleobiology is becoming the main applied branch of paleontology, but there are still few case studies. The authors outline four key research topics where paleobiological insights can contribute to elasmobranch conservation: (1) establishing historical baselines for elasmobranch abundances, (2) understanding the ecological roles of species, (3) identifying the threats they face, and (4) aligning research with current conservation priorities. Dillon and Pimiento argue that geohistorical records can provide critical long-term perspectives that extend beyond contemporary observations, helping to set realistic conservation targets and informing effective management strategies. One particularly relevant section refers to the use of fossil data to inform the IUCN Red List of endangered species by finding ecological and life-history correlates of empirical extinctions.

Ecosystem Origins

Porter et al. (Reference Porter, Riedman, Woltz, Gold and Kellogg2025) revisit the early diversification of eukaryotes, to which nearly all preserved body fossils belong. The authors challenge the widely accepted idea that eukaryotes underwent a rapid diversification during the Tonian Period in the Neoproterozoic. They present a new analysis of Proterozoic eukaryote diversity that reveals a strong correlation between the number of eukaryote species found and the number of formations studied. Based on this, Porter et al. (Reference Porter, Riedman, Woltz, Gold and Kellogg2025) argue that the perceived Tonian radiation might be an artifact of increased sampling, suggesting we are still only beginning to understand the true history of early eukaryotes. The authors encourage a shift in focus toward better exploring the Proterozoic fossil record to gain a more accurate picture of eukaryotic diversification.

Mitchell and Pates (Reference Mitchell and Pates2025) take a fresh look at the Precambrian/Cambrian boundary to discuss the most plausible drivers for this key time of early animal diversification. The authors explore the diversification of animal body plans, feeding strategies, and ecological interactions over the 75 Myr period from the middle Ediacaran into the middle Cambrian. Their analysis emphasizes the increasing complexity of ecosystems, transitioning from early Ediacaran communities dominated by passive filter feeders to the Cambrian, where a more structured, niche-driven system with specialized predators, prey, and ecosystem engineers emerged. Mitchell and Pates (Reference Mitchell and Pates2025) highlight key ecological innovations such as biomineralization, bioturbation, and the emergence of complex food webs, ultimately laying the foundation for the complex biosphere we see today. An avenue of future research may be in the delay between the advent of a novelty such as predation and the establishment of complex predation-structured food webs.

When and how did life conquer land? Boyce and Nelsen (Reference Boyce and Nelsen2025) synthesize information on terrestrialization across the tree of life and reveal potential cause–effect relationships in the evolution of life on land. Tackling not just plants and animals but also microbes and fungi, the authors highlight that all organisms initially inhabited the soil. Only when habitat providers such as plants provided opportunities could animals take advantage of these opportunities and evolve, for example, deeper borrowing and flight. The soil fauna has remained essentially constant since the Devonian at high taxonomic levels. Turnover and rapid radiation is only evident for those clades that made it out of their soil homes. The first step toward this extra-soil evolution was the invention of efficient herbivory, which is a major challenge because of the skewed nutrient ratios in plants. Depending on the definition of terrestrialization, the process may have been completed by the Devonian or is still ongoing if we consider pulmonate snails and brachyuran crabs. Boyce and Nelsen (Reference Boyce and Nelsen2025) argue that this ongoing terrestrialization may have been facilitated by increased productivity on land partly driven by the emergence of angiosperms.

Morphology and Phylogenetics

Quantifying morphology to study evolutionary trends, phylogenetic relationships, and how organisms interact with their environment has been an enduring theme of paleobiology for more than a century. Advances in this field have tended to track technological innovations, and Goswami and Clavel (Reference Goswami and Clavel2025) argue that the field is on the brink of another technological inflection point driven by the ability to rapidly create massive datasets of 3D imagery of fossils and to unleash artificial intelligence to find structure in the data. This new field of “evolutionary phenomics” promises several orders of magnitude increase in data density on hundreds of thousands of specimens for analysis. The authors summarize advances in quantifying morphology, morphospace analysis, phylogenetic comparative methods, and modeling expectations of disparity with different evolutionary models, pulling examples of their own work on mammal skull evolution (Goswami et al. Reference Goswami, Noirault, Coombs, Clavel, Fabre, Halliday and Churchill2022) and on linking morphological models with climate variables through time. These studies highlight the potential to join these methods with evolutionary phenomics.

Recent progress in building phylogenetic relationships has come from using Bayesian inference to estimate the joint posterior probability of the phylogeny, divergence times, and rates of speciation, extinction, and sampling for fossil and extinct taxa. This approach is called the fossilized birth–death (FBD; Heath et al. Reference Heath, Huelsenbeck and Stadler2014) process, which builds on the models of cladogenesis in Raup (Reference Raup1985) and is most often applied to datasets that include extinct and extant taxa but can also be applied to completely extinct groups (Wright Reference Wright2017; Congreve et al. Reference Congreve, Patzkowsky and Wagner2021). Mulvey et al. (Reference Mulvey, Nikolic, Allen, Heath and Warnock2025) review the application of FBDs over the last decade, introduce Bayesian inference used in FBDs, and explicitly discuss the unique issues presented by the fossil record. Future challenges include developing more realistic sampling models that reflect the structure of the fossil record and incorporating variable rates of morphological trait evolution. Both challenges require paleobiologists and model developers to work together to build the next generation of more realistic models.

Data Equity

Access to scientific knowledge, including the data used to generate that knowledge, should be openly available for all to use and interrogate. Paleobiological data pose specific challenges to accessibility, because they take so many forms, such as physical specimens housed in collections, electronic databases compiled from published scientific literature, and increasingly, high-density 3D scans of fossil specimens. Dunne et al. (Reference Dunne, Chattopadhyay, Dean, Dillon, Godoy, Smith and Raja2025) summarize the issues surrounding data equity in paleobiology that include not only the preservation, curation, and access of paleobiological data, but also the ethical collection and handling of the data. Most importantly, they provide a list of recommended actions for individuals and research teams, institutions, academic publishers and journal editors, and professional societies to improve data equity in the future. Of the many issues that they mention, open access in publishing is one area where professional societies and publishers can have a big impact. It is worth noting that with this issue of Paleobiology and moving forward into the future, all issues will be published as fully open access. Please see the Paleobiology page on the Cambridge Core website for details.