Scientists say a fossil of the oldest known octopus ancestor suggests that the animal lived before the dinosaurs.
The researchers have estimated the fossil is about 330 million years old.
It was discovered in what is now the western American state of Montana.
The fossil was donated to Canada's Royal Ontario Museum in 1988.
But it was not considered an important find for many years as scientists studied other fossils found at the same site.
But then some researchers discovered that the fossil showed the many limbs of an animal and began to study it further.
The 12-centimeter fossil has 10 limbs, each with two rows of suckers.
Modern octopuses have eight limbs.
The scientists say the ancient creature likely lived in shallow ocean areas.
The researchers say the fossil suggests that octopuses lived millions of years earlier than scientists believed.
This means that the animals developed before the dinosaurs.
The team recently reported its findings in the publication Nature Communications.
"It's very rare to find soft tissue fossils, except in a few places," Mike Vecchione told The Associated Press.
He is a zoologist with the Smithsonian National Museum of Natural History who was not involved in the study.
"This is a very exciting finding. It pushes back the ancestry much farther than previously known," Vecchione said.
Christopher Whalen is a scientist with the American Museum of Natural History in New York City.
He was a co-writer of the study.
He told the AP the well-preserved fossil showed evidence that the ancient octopus had the ability to release a dark liquid to help it hide from predators, just like modern octopuses.
The creature, known as a vampyropod, was likely the ancestor of both modern octopuses and vampire squid, the researchers said.
Such creatures are more similar to an octopus than a squid.
The team said until now, the "oldest known definitive" vampyropod was believed to have lived around 240 million years ago.
The scientists named the fossil Syllipsimopodi bideni, after American President Joe Biden.
They said they decided on the name to show respect for Biden's science and research policies.
I'm Bryan Lynn.