Scientists have unlocked new ways to study ancient marine life.
Researchers at the University of Southampton have developed a fossil analysis technique that reveals how prehistoric plankton responded to their environment on a day-to-day basis.
The findings, published on June 30 in the Proceedings of the National Academy of Sciences, open up new clues to understanding how environmental changes shape evolution.
Dr Anieke Brombacher, lead author of the study, said: "The fossil record provides the most powerful evidence of biodiversity change on Earth, but it traditionally does so at a scale of thousands and millions of years.
CT models of internal or external growth structures, as well as shell thickness, of individual foraminifera (Image: University of Southampton) "These fossils however act a bit like chapter summaries of a species’ evolutionary story.
"This new way of analysing them lets us read the pages within each chapter – allowing us to see how individual organisms adapted to their changing environment, not over the course of generations but within an individual life span at day-to-day resolution."
The team focused on foraminifera, or "forams," a type of tiny marine plankton with calcium carbonate shells.
These shells grow in a spiralling pattern, adding chambers every few days, much like tree rings.
Each chamber preserves a record of the organism’s environment, including water chemistry, depth, and temperature.
The researchers used high-resolution CT scanning and laser ablation chemical analysis to study these chambers in detail.
They found that while three species had similar growth rates at lower temperatures, one species grew significantly faster at higher temperatures, even though all reached the same average size.
Dr Brombacher added: "If you’re a foram, temperature appears to be a bigger determinant of your growth rate than even how old you are."
James Mulqueeney, a PhD researcher and co-author of the study, said: "We also found that of the two species with similar environmental sensitivities, one was able to reach the same size but with a thinner shell, indicating a lower energetic cost and potential evolutionary advantage."
The team believes this approach could be applied to other fossilised organisms, such as ammonoids, corals, and bivalves.
The study was funded by the Natural Environment Research Council (NERC) and forms part of a larger project examining whether adaptive flexibility in plankton leads to the emergence of new species over time.
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