Fossil record links marine diversity peaks to climate state

How did researchers compare half a billion years?

The team used the Paleobiology Database, an online resource that documents the published fossil record of past life. Its records describe marine invertebrates across roughly 500 million years.

The reconstruction involved four main steps:

• Researchers inferred each fossil’s ancient geographic location.
• They divided the globe into map-grid cells of equal area, each covering the same amount of Earth’s surface, about 250 km (155 miles) apart.
• They applied coverage-based rarefaction, a statistical method for comparing samples with different amounts of sampling.
• They measured biodiversity by latitude in each hemisphere and compared the results across five global climate states, from cold to extremely warm.

That last comparison matters because some regions have more fossils than others. Rarefaction helped reduce the risk that uneven sampling, rather than real ecological differences, would drive the result.

Bottom line: The analysis compared diversity estimates adjusted for sampling differences across deep time and a range of global climates.

Why might climate move biodiversity peaks?

One possible explanation, Wen said, is that warming shifts suitable thermal habitats toward higher latitudes. As those temperature zones move poleward, tropical environments may become less suitable for some species, potentially reducing tropical diversity.

The fossil patterns show an association between climate state and biodiversity, not a single proven mechanism. Other influences may sit behind the pattern, which is why the researchers plan to test several explanations rather than treat that link as a complete explanation.

Bottom line: Climate can alter where marine animals can live, and the fossil record shows that this changes the geography of diversity.

What does the study suggest about global warming?

The findings suggest that continued warming could eventually alter where marine life is most diverse. They do not provide a timetable or identify which regions would gain or lose the most species.

“Understanding how biodiversity might respond to global climate change is crucial to the conservation of life on Earth, with the fossil record providing our only window into the long-term effects of major environmental change,” said Mannion.

With warming expected over the next century, the authors said marine diversity might decline in the tropics and shift toward the poles. That redistribution could occur at least among species able to disperse, meaning they can move into new areas.

Two limits stand out:

• The analysis does not establish how quickly modern marine diversity patterns might change.
• It does not identify which regions would gain or lose the most species.

The result therefore offers long-term context, not a forecast for a particular coastline or decade.

Bottom line: The study points toward declining tropical diversity and poleward shifts, but not their speed or location.

What will the team examine next?

The researchers plan to investigate continental drift, the availability of shallow-marine habitat and species’ thermal preferences. Shallow-marine habitat means shallow coastal waters available to marine organisms; thermal preferences are the temperature conditions different species favor.

They also want to compare the ancient fossil data with more recent records of marine life. The team will combine fossils with paleoclimate simulations, or modeled past climates, and Earth system models that represent the planet’s broader physical system.

Wen said this combination could clarify how environmental changes shape biodiversity distributions and contribute to major evolutionary events, including mass extinctions. The paper’s DOI is 10.1098/rspb.2026.1490.

Bottom line: The fossil record establishes a climate link; the next stage is to determine which Earth processes drive it.