CHICAGO, Feb. 8 (UPI) -- A new study published in the journal Cretaceous Research triples the number of species belonging to the genus Rhinconichthys, a type of large-mouthed fish that swam the oceans 92 million years ago.
Previously, there was only one known Rhinconichthys specimen, discovered in England. But a skull recently unearthed in Colorado and the reconsideration of a fossil in Japan has upped that number to three.
"I was in a team that named Rhinconichthys in 2010, which was based on a single species from England, but we had no idea back then that the genus was so diverse and so globally distributed," Kenshu Shimada, a paleobiologist at DePaul University, explained in a press release.
Like modern day whale sharks, all three fish used expansive mouths to gulp down large amounts of plankton. But unlike the larger whale shark, Rhinconichthys species stretched about 6.5 feet in length and boasted a mostly bone skeleton -- not cartilage.
Given the geographical spread of the Rhinconichthys fossils, researchers say it's likely they will eventually uncover more specimens.
"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," Shimada said. "This tells just how little we still know about the biodiversity of organisms through the Earth's history. It's really mind-boggling."