A new analysis published in AGU Eos reports that squid and other cephalopods had already spread significantly across the world's oceans by 67 million years ago — well before the asteroid impact that ended the age of dinosaurs. The finding suggests these animals were not confined to a few regions but had established a broad global presence early in their evolutionary history.
This pre-impact dispersal may explain why cephalopods thrived while many other marine groups struggled after the Chicxulub event. The researchers argue that their wide geographic range likely provided resilience, allowing populations to survive local disruptions and repopulate affected areas. The pattern seen today, with squid inhabiting nearly every ocean, appears to have been set in motion long before the mass extinction.
The study underscores how ancient biogeography can shape modern biodiversity. By tracing where species lived before major crises, scientists gain insight into which traits — such as wide distribution — confer survival advantages over deep time. The authors note that this early mobility was a key factor in the lineage's enduring success.