Fossil records can suggest which modern marine species would be at risk of extinction in the absence of human activity.

Seth Finnegan at the University of California, Berkeley, and his team used fossils from the past 23 million years to examine the extinction risk of 2,897 genera from 6 groups — sharks, marine mammals, scleractinia corals, bivalve molluscs, echinoderms such as sea urchins, and snails.

They found that small geographic ranges consistently increased extinction risk, and that some broad taxonomic groups had a consistently higher extinction risk than others. Mapping these two features onto modern relatives of these six groups shows the distribution of baseline extinction risk, with hotspots in the Indo-Pacific and Western Atlantic tropics. Overlaps between this baseline and human-derived pressures could point to areas of particular vulnerability.

Science 348, 567–570 (2015)