Overview
- An OIST-led team reports in Nature Ecology & Evolution the first genome-based evolutionary tree for squids and cuttlefish built from nearly all major lineages and recent fossil finds.
- The analysis places their origins in the mid-Cretaceous about 100 million years ago, rooting early decapodiform evolution in the deep ocean.
- The authors argue ancestors survived the dinosaur-era mass extinction by retreating into small, oxygen-rich refuges far below the troubled surface waters.
- As shallow seas and reefs recovered, lineages rapidly diversified into coastal habitats in a “long fuse” pattern after tens of millions of years with little branching.
- A five-year global effort, including the Aquatic Symbiosis Genomics Project, added three new squid genomes and rare species like the ram’s horn squid to overcome sparse fossils and very large genomes.