The Cambrian radiation represents one of the most significant evolutionary events in the history of life, marked by the rapid appearance and diversification of major animal groups and the increasing complexity of marine ecosystems. Previous studies have largely focused on the dramatic rise in global biodiversity and morphological disparity during this interval. However, an increase in global diversity can result either from greater species richness within individual communities or from increasing differences in species composition among regions. How these two processes contributed to the Cambrian radiation remains an important question in evolutionary palaeobiology.
Recently, Dr. NA Lin and Associate Professor LI Qijian from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with Dr. Ádám T. Kocsis and Professor Wolfgang Kiessling from Friedrich-Alexander University Erlangen–Nuremberg, Germany, investigated the Cambrian radiation from a spatial perspective. Their findings have been published in Geological Society, London, Special Publications.
A key data source for this study was the Geobiodiversity Database (GBDB), an independently developed palaeontological database with proprietary intellectual property rights held by NIGPAS. The researchers integrated fossil occurrence records from GBDB with those from the international Paleobiology Database (PBDB). Because the global fossil record is unevenly sampled across different palaeocontinents, the incorporation of GBDB records, particularly those from South China and neighbouring Gondwanan terranes, helped improve data coverage along the eastern margin of Gondwana.
The combined dataset comprised 9,800 fossil collections, 39,972 species occurrences, 3,527 genera, and 11,220 species, providing a substantial foundation for quantitatively reconstructing the spatial organization of marine biodiversity from the latest Ediacaran to the earliest Ordovician.
Using plate tectonic reconstructions, the research team restored fossil occurrences to their palaeogeographic positions and analysed biodiversity patterns across multiple spatial frameworks, including equal-area grids, palaeogeographic plates, and palaeolatitudinal bands. They combined diversity partitioning, network analysis, and assessments of endemism and latitudinal differentiation to investigate how marine faunal distributions changed throughout the Cambrian.
The researchers first partitioned global diversity (gamma diversity, γ) into local diversity (alpha diversity, α) and differences in taxonomic composition among regions (beta diversity, β). Their results revealed that, after accounting for sampling differences, global diversity increased substantially from the Fortunian to Cambrian Stage 3, whereas average local diversity did not show a corresponding increase. Instead, beta diversity rose sharply during the early Cambrian and was strongly associated with changes in global diversity.
These findings indicate that the early Cambrian increase in global biodiversity was driven to a considerable extent by increasing differences in faunal composition among regions, rather than simply by the accumulation of more taxa within individual local communities. Further partitioning of beta diversity showed that these differences were overwhelmingly dominated by taxonomic turnover, rather than nestedness, suggesting that different regions increasingly hosted distinct assemblages of marine animals.
Network analyses provided additional evidence for this emerging spatial structure. Faunal networks showed relatively low connectivity throughout the Cambrian, while modularity increased markedly from the Fortunian to Cambrian Stage 4. This pattern indicates the progressive establishment of relatively distinct regional faunas during the early stages of animal diversification. In other words, the Cambrian radiation involved not only the rapid diversification of animal taxa but also the emergence of pronounced biogeographic provinciality. The development of geographically differentiated marine communities was therefore an integral component of the early evolution of complex marine ecosystems.
The study also identified persistently high levels of endemism throughout the Cambrian. Species-level endemism was consistently higher than genus-level endemism across the different spatial frameworks and time intervals examined, indicating stronger geographic restriction at finer taxonomic levels. Although estimates of endemism may be influenced by incomplete fossil sampling, these patterns suggest that geographic differentiation remained a prominent feature of Cambrian marine faunas.
Importantly, the early Cambrian increase in beta diversity persisted even after endemic taxa were excluded from the analyses. This suggests that the emergence of distinct regional faunas was not driven solely by the evolution of geographically restricted taxa. The spatial reorganization of more widely distributed taxa also contributed substantially to the development of Cambrian biogeographic structure. The researchers propose that environmental heterogeneity among palaeocontinents and continental shelves, including differences in substrate conditions, water depth, and redox environments, together with variation in dispersal capabilities among organisms, may have promoted regional differentiation. Ecological changes associated with the Cambrian substrate revolution may also have contributed to this process.
Interestingly, the study found that Cambrian biogeographic differentiation was not primarily organized along simple latitudinal gradients. Comparisons of beta diversity within and between palaeolatitudinal bands revealed relatively modest differences. Even within Gondwana and its associated terranes, faunal differentiation between latitudinal bands was only slightly greater than that within the same bands. These findings suggest that palaeogeographic configuration, regional environmental heterogeneity, and dispersal limitations may have been more important than latitude alone in shaping Cambrian marine biogeography.
During the middle and late Cambrian, the biogeographic structure established earlier did not disappear but underwent continued reorganization. Although endemism remained high, increasing sharing of non-endemic taxa among regions contributed to a decline in overall beta diversity. This suggests that Cambrian biogeographic patterns evolved through a dynamic interplay of extinction, dispersal, recolonization, and environmental change, rather than following a simple transition from provinciality to global faunal homogenization.
Overall, the study demonstrates that the Cambrian radiation cannot be understood solely in terms of how many animal taxa evolved globally. The rapid increase in global biodiversity was accompanied by pronounced differentiation among regional faunas and the early establishment of biogeographic provinces. In this sense, the Cambrian radiation was not only a “radiation of taxa” but also a “radiation of places.” These findings provide a new spatial perspective on the emergence and early evolution of marine animal biodiversity.
Beyond its scientific findings, the study highlights the growing value of GBDB as a research infrastructure for global palaeobiodiversity studies. By integrating the extensive fossil records of China and neighbouring Gondwanan regions available through GBDB with data from international databases, researchers can improve the geographic coverage of deep-time biodiversity datasets and strengthen quantitative investigations of palaeobiogeography and macroevolution.
The research was published in Volume 565 of Geological Society, London, Special Publications, as part of the volume Geography and Life Before Pangaea: a Volume in Honour of Robin Cocks.
Reference: Na, L., Li, Q., Kocsis, Á. T. & Kiessling, W. (2026). From radiation to provinces: spatial scaling of Cambrian diversity. Geological Society, London, Special Publications, 565. https://doi.org/10.1144/gslspecpub2026-20.
Fig. 1. Palaeogeographic distribution of fossil occurrences from the latest Ediacaran to the earliest Ordovician (Tremadocian). Each panel shows occurrences reconstructed to their palaeogeographic positions using the PALEOMAP v3 plate motion model (Scotese 2016). Continental configurations are reconstructed at the middle age of each interval. Orange dots represent occurrences from the Paleobiology Database (PBDB); red dots represent occurrences from the Geobiodiversity Database (GBDB). Ma, millions of years ago.
Fig.2. Genus- and species-level endemism through Cambrian calculated at three geographic scales (cell5, cell7 and geoplates). Endemism remains persistently high throughout the Cambrian. Species-level endemism is consistently higher than genus-level endemism in all intervals. Bootstrap means (400 replicates) and 95% confidence intervals are shown. Ages are in millions of years (Ma).
Download：