【#Tech24H】Scientists at the Okinawa Institute of Science and Technology (OIST) combined existing genetic databases with newly sequenced genomes of three squid species, and collaborated with an international research team, to reconstruct together the most complete evolutionary family tree of decapodiform cephalopods to date. The results indicate that the ancestors of squid and cuttlefish likely originated in the deep sea. Around the mid-Cretaceous, about 100 million years ago, their ancestors began to rapidly diverge into multiple evolutionary lineages. The real turning point occurred around 66 million years ago. The famous Cretaceous-Paleogene extinction event (K-Pg impact event), which wiped out about three-quarters of all plant and animal species on Earth, including dominant groups like the dinosaurs, made shallow marine environments extremely harsh due to ocean acidification and anoxia. However, some deep-sea areas served as refuges for ancient cephalopods. It was during this period that the evolutionary branches of squid and cuttlefish suddenly increased, gradually giving rise to the rich diversity of species we see today.