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Friday Squid Blogging: When the Octopus and Squid Lost Their Shells

Cephalopod ancestors once had shells. When did they lose them? With the molecular clock technique, which allowed him to use DNA to map out the evolutionary history of the cephalopods, he found that today’s cuttlefish, squids and octopuses began to appear 160 to 100 million years ago, during the so-called Mesozoic Marine Revolution. During the revolution, underwater life underwent a…