This Plankton Eating Fossil Fish Had A Super Wide Mouth

The fishes comprise two of three in the genus Rhinconichthys that are plankton eaters.

Rhinconichthys were plankton eaters that could expand their jaw super wide, like Kermit the Frog. Image by Robert Nicholls

Two fish that swam the oceans more than 92 million years ago were recently discovered in Colorado, giving three distinct species to the genus Rhinconichthys. The two species R. purgatoirensis and R. uyenoi were suspension feeding bony fish that lived during the mid Cretaceous Period. in the United States. The illustration of the fish makes it looks like it is a Muppets character, with its super wide jaw that opens extra wide.

“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,” Kenshu Shimada, a paleobiologist at DePaul University said. “This tells just how little we still know about the biodiversity of organisms through the Earth’s history. It’s really mindboggling.”

Rhinconichthys are from an extinct bony fish group that are called pachycormids. They fed on plankton, and like the basking shark and whale shark, swam around with a massive mouth wide open, filtering plankton as they swam. The scientists estimate that the fishes were about six feet in length and had a unique pair of bones that enabled the fish to swing their jaws extra wide,  like a parachute in order to capture more plankton in the waters in which they swam.

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Fish · Lifestyle