New fossil research shows that shallow, coastal, species-rich habitats have long fueled shark and ray diversification, but development, warming, pollution, and overfishing are now threatening these crucial nurseries and feeding grounds.

Today’s biodiversity crisis differs from past events in part because rapid change gives sharks and rays little time to adapt or migrate, making highly specialized groups—like certain deep-sea sharks—especially vulnerable to warming.

The fossil record underscores the importance of extensive shallow coastal habitats (reefs, seagrass meadows, nearshore systems) as nurseries and feeding grounds driving neoselachian evolution, all of which are increasingly threatened by human pressures.

The study, published in Scientific Reports on November 20, 2025, is led by Manuel A. Staggl of the University of Vienna, with contributions from Jürgen Kriwet and the Institute of Palaeontology.

Analyzing 49,750 fossil occurrences across 503 genera, the researchers reconstruct Cenozoic diversity, finding a mild post‑Cretaceous dip, a strong radiation with an Eocene peak, and a long-term decline without full recovery.

Overall, the work reframes neoselachian evolutionary history and offers data-driven guidance for modern conservation strategies.

The publication’s formal title is Global environmental drivers shape cenozoic neoselachian diversity and identify modern conservation priorities, with DOI 10.1038/s41598-025-25653-6.

The study advocates preserving and restoring diverse coastal habitats and aggressively reducing CO2 emissions to curb ocean acidification, stressing a holistic approach to marine conservation beyond fishing quotas.

A new fossil analysis shows sharks and rays have experienced a 100-million-year decline in genus diversity since a warm Eocene peak about 45 million years ago, challenging the idea of stable or increasing modern diversity.

Deep-sea sharks followed a distinct trajectory, expanding during surface-water cooling as lineages moved to deeper or higher-latitude waters, still reflecting long-term ocean geography and climate shifts.

Sharks and rays have shown resilience to mass extinctions, with the asteroid event around 66 million years ago causing only a minor disruption and diversity peaking in the warmer Eocene.

Atmospheric CO2 had a nuanced effect: moderate levels historically supported productivity and diversity through habitat growth, but excessive CO2 drives ocean acidification and harms modern biodiversity.