Ancient squids dominated the ocean 100 million years ago, fossil discovery technique reveals

One of the study's most striking discoveries was how common squids were in ancient oceans. The team found that squid fossils far outnumbered those of ammonites and bony fishes. Ammonites are extinct shelled relatives of squids and have been considered among the most successful swimmers of the Mesozoic era.

https://phys.org/news/2025-06-ancient-squids-dominated-ocean-million.html