A novel application of radiocarbon dating suggests that the Greenland shark (Somniosus microcephalus) is the longest-lived vertebrate known, boasting a lifespan of at least 272 years. Julius Nielsen of the University of Copenhagen and colleagues dated eye-lens nuclei from 28 female Greenland sharks measuring 81–502 cm in length using the pulse of carbon-14 produced by nuclear tests in the 1950s. Only the smallest sharks (measuring 220 cm or less) showed signs of the radiocarbon bomb pulse, which is a time marker of the early 1960s. The age of the sharks at sexual maturity was 156 ±22 years and the largest shark was 392±120 years old, suggesting that some Greenland sharks today were alive at the same time as Copernicus.