A newly described fossil reveals that leeches are at least 200 million years older than scientists previously thought, and that their earliest ancestors may have feasted not on blood, but on smaller marine creatures. 

“This is the only body fossil we’ve ever found of this entire group,” said Karma Nanglu, a paleontologist with the University of California, Riverside. He collaborated with researchers from the University of Toronto, University of São Paulo, and Ohio State University on a paper describing the fossil, which is now published in PeerJ.

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