Scientists Discover Two New Fossil Fish Species With Gigantic Mouths

There are still massive species of whales and other types of sea creatures that eat some of the smallest creatures in the sea known as plankton. In the distant past, there were massive sea creatures who feasted on the same sort of plankton in the ocean waters and scientists have found two new examples of plankton-eating fossilized fish. The new fossils are in the genus Rhinconichthys and swam in the oceans of the Cretaceous Period about 92 million years ago.

One of the scientists who authored the study about the new fossils is Kenshu Shimada, a paleobiologist at DePaul University. Shimada said that these fossils are very rare and the only previously known example was a fossil discovered in England. Recently a new fossilized skull was found in Colorado. Along with the discovery of the new skull, a previously discovered fossil from Japan was re-examined as well.

The new species found in Colorado was called R. purgatoirensis and the Japanese skull was called R. Uyenoi. "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," said Shimada. The team's findings will be published in a study called, "Highly specialized suspension-feeding bony fish Rhinconichthys (Actinopterygii: Pachycormiformes) from the mid-Cretaceous of the United States, England and Japan."

The research team says that Rhinconicthys belongs to an extinct group of bony fish that are called pachycormids that contain the largest bony fish that ever lied on Earth. The new study specifically focuses on members of the group that ate plankton. The fish are estimated to be more than 6.5 feet long and feature a pair of bones called the hyomandibulae.

Those bones formed an oar-shaped lever that could protrude and open the fish's jaws extra wide to allow the fish to get more plankton-filled water inside its mouth. Another name for a plankton-based diet is suspension feeding and modern sea creatures like the Blue Whale, Manta Ray, and Whale Shark all feed this way today.

"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 noted. "This tells just how little we still know about the biodiversity of organisms through the Earth's history. It's really mindboggling."

SOURCE: Eurekalert