Could warming seas bring great white sharks back to the North Sea? A 5‑million‑year‑old shark tooth may provide clues

As Earth shifts to climates not seen for several hundred thousand years, we may need to look at ancient environments for clues about what could happen next. The science-journalism coverage adds useful context, while the strongest evidential footing still comes from the underlying data, papers or institutional documentation.

It matters because Earth science becomes stronger when local observations can be placed inside a broader physical pattern that spans time and geography. The planet operates as a coupled system in which atmospheric, oceanic, cryospheric and solid-Earth processes interact across timescales from days to millions of years. A measurement that captures one variable at one location and one moment has limited interpretive value until it is embedded in the longer series and wider spatial coverage that allow natural variability to be separated from forced change. By John Stewart, Olivier Lambert, The Conversation This article has been reviewed according to Science X's editorial process and policies. Our new study of two whale fossils, with preserved fragments of shark teeth, suggests the modern descendants of these animals could once again roam the southern region of the.

Paleoecology, the study of the interactions between organisms in the deep past, has been co-opted in the service of conservation science for some years now. But about 4, 5 million years ago, the North Sea was home to several large shark species, including the now locally extinct bluntnose sixgill shark and a relative of the modern.

This is what we found in two cetacean skulls from the Early Pliocene (approximately 5, 4 million years ago) of the North Sea. Discover the latest in science, tech, and space with over 100, 000 subscribers who rely on Phys. org for daily insights.

The first of these two skulls belonged to a diminutive extinct right whale which was found by father and son fossil enthusiasts (Robert and John Stewart, co-author of this piece). Some 40 or so years later, the skull was donated to the Institute of Natural Sciences in Brussels, where it was identified by one of us (Olivier Lambert) as one of only two fossil.

The broader interest lies in linking the observation to climatic, geophysical or environmental dynamics that extend well beyond the immediate event or location. Earth science is unusual in that its most important questions operate on timescales that no single research career can observe directly, making the archival record, whether in ice, sediment, rock or satellite data, as important as any new measurement. Results that can be embedded in that record, and that either confirm or challenge the patterns it reveals, carry disproportionate scientific weight.

The second skull, from a close relative of the extinct beluga whale Casatia thermophila, was discovered in the early 1980s. It was found during the excavation of a new dock in the Port of Antwerp by another father and son team, Paul Gigase, a pathologist by profession, and his son Pierre.

Because this item comes through Phys. org Biology as science journalism, it should be treated as contextual reporting rather than primary evidence. Good science reporting can identify why a result matters, connect it to the wider literature and make technical work readable, but the decisive evidence remains in the original paper, dataset, mission release or technical record. That distinction is especially important when a story is later repeated by aggregators, because repetition increases visibility, not evidential strength.

The next step is to place the result inside longer time series and to compare it with independent instruments and independent sites. Earth system observations gain most of their interpretive power from network density and temporal depth, not from any single measurement however precise. Model simulations that assimilate the new data will help clarify whether the observation fits comfortably within known natural variability or represents a shift that existing models do not reproduce.

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