The fish Bonnerichthys swam in the prehistoric seas between 66 million and 172 million years ago. The toothless plankton-eater used Its large mouth to gulp as much water as possible through its gills. Some members of the species were estimated to grow up to 27 feet long.

A large fish fossil that sat at Kansas University for decades has provided new insight into the history of modern-day large plankton-eaters.

KU researchers joined other scientists from across the globe with similar specimens in reporting their findings in this week’s Science magazine.

The toothless, plankton-eating fish, estimated to reach lengths of up to 27 feet, is related to similar modern-day fish like the basking shark.

KU’s specimen joins similar ones found in Japan, England and other places, indicating the fish swam all over the world. That includes Kansas, during a period when the state was resting under an ocean of salt water.

Larry Martin, KU’s director of vertebrate paleontology, said KU had the 80-million-year-old fossil — the head, jaw and some fins — for decades without recognizing its significance.

“It’s about as complete a fossil as you’ll find for this kind of fish,” said Martin, adding that most of the fish was made of cartilage and wasn’t preserved.

The new group of fish is named Bonnerichthys after the Marion Bonner family from Leoti, Kan., which found the fossil years ago in the chalk deposits of Logan County in Western Kansas.

Orville Bonner, the oldest of eight children in the fossil-finding family, lives in Lawrence today. He had worked with fossils for KU — including the fossil that now bears his family name — before retiring in 1997.

“I knew that this was something very strange,” Bonner said, when his family found it decades ago.

He recalled especially the large, bony eye sockets of the fish.

“You could fit a volleyball in there,” he said.

The Bonner family worked for years finding fossils, providing specimens for KU and the Sternberg Museum in Hays. Bonner remembered how his father would search for fossils during the day and operate a movie theater at night.

The family would often sell the fossils, but usually only generated enough to get gas money to go back out to try and find some more.

Bonner said he was honored to have the family name attached to the fish, and remembered the family’s joy after his father and brother found it.

“It’s what it’s all about,” Bonner said. “You could find something that nobody’s ever seen before. That’s what keeps you going.”

Researchers had previously thought the oceans were devoid of this type of large fish during the period that these fossils date to — between 66 and 172 million years ago. The fish is believed to have gone extinct at the same time the dinosaurs did.

“Discovery isn’t the first time you find something, it’s the first time you realize what you’ve found,” Martin said.