A pair of fossils from an exceedingly rare, plankton-eating, dinosaur-era fish have been unearthed, shedding new light on an animal with a specialized jaw that could open extra-wide at meal time.

The new fossils come from the genus Rhinconichthys, samples of which are very tough to come by: Just one other fossil was known, from a find in England. But now, thanks to a re-examination of a skull from Japan and a new skull found in Colorado, a team of scientists from the United States and the United Kingdom is getting a better idea about how the fish ate and how widely distributed it may have been.

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The big-mouthed fish lived during the Cretaceous, some 92 million years ago, and patrolled the ocean feasting on plankton.  A specialized, lever-like pair of bones in its jaw allowed its mouth to open extremely wide, to take in as much plankton as it could.

Scientists call this form of food intake “suspension feeding” -- seen today in creatures such as the manta ray, blue whale, and whale shark -- and say it’s still a new area of inquiry in creatures from the dinosaur era.

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Details about the new finds will appear in a study to be published in the next issue of the journal Cretaceous Research.

“Based on our new study, we now have three different species of Rhinconichthys, from three separate regions of the globe, each represented by a single skull,” said study co-author Kenshu Shimada, a paleobiologist from DePaul University.

“This tells just how little we still know about the biodiversity of organisms through the Earth’s history. It’s really mind-boggling,” Shimada added, in a press release.