The fossil whorls were a mystery. In 1899, geologist Alexander Karpinsky described an odd spiral of teeth, the first known fossil of its kind, uncovered from the ancient rocks of Krasnoufimsk, Russia.
PORTLAND, Maine — Sharks are the most feared predators in the sea, and their survival hinges on fearsome teeth that regrow throughout their lives. But changes in the ocean's chemistry could put those ...
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