The creature’s discovery pushes back the time frame when vampyropods, the group to which cephalopods like octopuses belong, appeared in the ocean by almost 82 million years.

Vampyropods are known for having eight legs, an internal shell made of chitin and a soft body — the last of which doesn’t show up often in the fossil record because it tends to deteriorate more quickly than hard structures like bone.

A well-preserved fossil was discovered in Montana’s Bear Gulch Limestone formation and donated to Canada’s Royal Ontario Museum in 1988. The specimen represents the earliest-known ancient relative of these creatures, a new analysis of the fossil revealed.

“This is the first and only known vampyropod to possess 10 functional appendages,” said study author Christopher Whalen, a postdoctoral researcher in the American Museum of Natural History’s Division of Paleontology, in a statement.

“All previously reported fossil vampyropods preserving the appendages only have eight arms, so this fossil is arguably the first confirmation of the idea that all cephalopods ancestrally possessed ten arms.”

Syllipsimopodi is the best known fossil for understanding how vampyropods originated, as well as helping researchers to trace their evolution, said Whalen, who is also a National Science Foundation postdoctoral fellow in Yale University’s Department of Earth & Planetary Sciences.

It has long been thought by researchers that the vampyropods began with 10 arms and eventually lost two of them over time — and now, scientists have direct evidence.

Tiny but mighty

The detailed fossil clearly shows a creature about 4.7 inches (12 centimeters) long with 10 arms, with the suckers still attached — an incredibly rare find since these arms were essentially just muscle. Two of those arms seem to be longer than the other eight, and its body was shaped like a torpedo, similar to modern squid. The researchers also found remnants of its ink sac.

Soft-bodied cephalopods are divided into vampyropods and decabrachians.

Vampyropods include octopuses and vampire squids, both of which are different from actual squid. Vampire squid basically look like octopuses with a built-in parachute because they have a membrane that stretches between and connects their arms. They also have two structures to help them feed called filaments in addition to their eight arms.

Meanwhile, decabrachians include modern squids and cuttlefish, which have 10 arms, including 2 tentacles. There are a number of differences that separate cephalopods like squid and octopuses, but the number of arms is one of the most recognizable.

So why is this fossil considered to be a vampyropod, even though it has 10 arms?

The team’s phylogenetic analysis, which indicates evolutionary relationships, placed the species within the vampyropod side of the evolutionary tree, Whalen said.

The new species…

Source: Fossil of 328 million-year-old octopus relative still has suckers on its arms