How Shallow Seas Shaped the Rise of Modern Sharks

Sharks, rays, and their extinct relatives—collectively known as Neoselachii—are some of the most ecologically significant vertebrates in our oceans. While we know they are survivors, the specific environmental triggers behind their evolution have remained unclear. A new study using high-resolution fossil data has mapped their diversity through the Cenozoic era, revealing that the KPg mass extinction had a much milder impact on these groups than previously suggested.

Following this survival, these marine creatures underwent a period of rapid expansion, culminating in a diversity peak during the Eocene. The research identifies a specific catalyst for this explosion of life: shallow, heterogeneous habitats. These complex, varied environments acted as the primary driver for diversification, allowing different species to adapt to unique ecological niches. Additionally, the team identified two distinct shifts in animal composition during the Miocene epoch. Unravelling these ancient patterns provides essential context for understanding current biological resilience, helping scientists design better conservation strategies to protect these species from modern anthropogenic pressures.