Some 23-million-year-old teeth that were forgotten in storage suggest the ancient existence of a newly-discovered species of megamouth shark.
"It was a species that was known to be a new species for a long time," study co-author Kenshu Shimada, a paleobiologist at DePaul University in Chicago, told LiveScience. "But no one had taken a serious look at it."
Researchers found the teeth in the 1960s, but the beast was so unknown they didn't even know where to begin and put the finding on the back burner. Through the years more teeth were found along the California and Oregon coast, but all were left to gather dust in the storage drawers of nearby museums.
In 1976 researchers discovered the Megachasma pelagios, or modern megamouth shark. The animals use their unusual mouth to feast on plankton by filtering water through their gills, which send the morsels straight into the shark's digestive tract.
Shimada noticed the ancient shark teeth at the Los Angeles County Museum. He asked the researchers who had given up on the teeth to take a look with him.
They found the teeth belonged to M. pelagios, but were longer and sharper than the modern species'.
"That suggests that they probably had a wider food selection," Shimada told LiveScience. "They could have probably eaten plankton, but they were also probably feeding on fish."
The researchers believe the creature hunted in both shallow and deep waters looking for prey. The shark probably had a shorter snout than its modern relative. It may have grown to an average of 20-feet-long, but could have reached up to 27 feet in length; this is a similar size to M. pelagios.
Researchers are not sure why these (still unnamed) M. pelagios relatives evolved their filter-system for eating and developed a wider mouth.
The research will be published in the journal Vertebrate Paleontology
