A group of prehistoric fish that existed for more than 100 million years fed by filtering tiny organisms from ocean water, just as baleen whales do today, paleontologists say.
The fish, which grew to several metres in length, took great mouthfuls of water and filtered out food as the water escaped through their gill slits, researchers say.
Variations on the feeding method are seen today in some of the largest creatures in the ocean, such as baleen whales, whale sharks and manta rays.
Paleontologists in the U.S. and U.K. found several examples of large, filter-feeding bony fish from fossils found in Asia, Europe and North America.
The fossil remains the scientists found include pieces of fin, tail and skull, including bony gill structures thought to be used in filter feeding.
Matt Friedman of Oxford University and his colleagues examined new fossils and analyzed old, mislabelled ones sitting in museums to determine that these large, bony fish lived from 170 million to 65 million years ago, from the middle of the Jurassic era to the end of the Cretaceous.
Previously, paleontologists believed that prehistoric plankton-feeding bony fish lived only for a relatively short time, 20 million years, during the Jurassic era.
The research appeared this week in the journal Science.