Molecular Paleontology Reveals Secrets of Octopus, Cuttlefish, and Squid Evolution

Octopus, cuttlefish, and squid are well known in the invertebrate world. With their ink-squirting decoy technique, ability to change color, bizarre body plan, and remarkable intelligence, they highlight that lacking a back-bone doesn't always mean lacking sophistication. Examining their deep evolutionary past, researchers have been spoiled by their generous fossil record, as demonstrated by drawer after drawer of ammonites and belemnites in every natural history museum shop. But, the mostly shell-less modern cephalopods have been less easy to understand. Now, a new study, led by researchers from the University of Bristol (UK), has found out how these remarkable creatures evolved by comparing their fossil records with the evolutionary history chronicled in their gene sequences to shed light on their origins. Published online on February 28,2017 in Proceedings of the Royal Society B, the study shows that the cephalopods diversified into the familiar modern octopuses, cuttlefish, and squid during a time of great change in the marine world, known as the Mesozoic Marine Revolution, 160 to 100 million years in the past. Lead author, Al Tanner, a Ph.D. student at the University of Bristol's School of Biological Sciences, is a molecular biologist and bioinformatician at the Bristol Palaeobiology Research Group--a world leading evolutionary research group. He said: "On land this was the time of the dinosaurs, but beneath the seas, ecologies were changing rapidly. Fish, squid, and their predators were locked in evolutionary 'arms-races,' leading to increasingly speedy and agile predators and prey.
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