Drawing of white squid-like creature in front of blue background
Drawing of white squid-like animal in blue water

Ten-Limbed Octopus Ancestor Described, Named After Biden

Octopuses were around 82 million years earlier than scientists previously thought—and had two extra limbs at the time.

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Natalia Mesa

Natalia Mesa is an intern at The Scientist. She has a PhD in neuroscience from the University of Washington and a bachelor’s in biological sciences from Cornell University.

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Mar 10, 2022

ABOVE: Artistic reconstruction of Syllipsimopodi bideni K. Whalen/Christopher Whalen

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 330 million-year-old creature found fossilized in limestone may be the oldest known relative of octopuses, according to a study published in Nature Communications on Tuesday (March 8). The remarkably well-preserved, 10-legged creature died in a tropical bay located in what is now Fergus County, Montana. The scientists decided to name it Syllipsimopodi bideni after US President Joe Biden.

According to The New York Timesthe fossil was originally donated to the Royal Ontario Museum in Canada in 1988. But it sat in undisturbed in a drawer for decades until Christopher Whalen, a paleontologist at the American Museum of Natural History in New York, pulled it out, inspected it, and noticed its preserved arms were covered in tiny suckers. 

“It’s very rare to find soft tissue fossils, except in a few places,” Mike Vecchione, a zoologist at the Smithsonian National Museum of Natural History who was not involved in the study, tells The Guardian. Unlike animals with shells and skeletons, soft-bodied animals don’t show up in the fossil record often because their bodies degrade quickly. “This is a very exciting finding. It pushes back the ancestry much farther than previously known.”

Syllipsimopodi bideni fossil from Bear Gulch Montana Limestone
Christopher whalen

According to the study, the oldest known definitive vampyropod was found in a fossil fragment that was 240 million years old, so the researchers mostly expected to find cephalopods that were evolutionary precursors to vampyropods. Instead, they discovered what they say is a relative of vampyropods and octopuses, which serves as evidence that these animals lived on Earth 82 million years earlier than previously thought. This would mean that octopuses were around before the era of dinosaurs, reports the Guardian

The S. bideni specimen is 4.7 inches long and has 10 appendages lined with suckers. Its body is torpedo-shaped, and two of its arms were twice as long as the other eight, similar to modern squid. The researchers also found evidence of an ink sac, reports CNN.

The scientists decided to name the species after Biden to commemorate the start of his presidency and because the researchers “were encouraged by his plans to address climate change and to fund scientific research,” Whalen tells the Times. 

Vampyropods, a phylogenetic group that includes octopuses and vampire squid, which despite their name are closely related to octopuses, have eight arms, an internal shell made of chitin, and a soft body. They are one of just two extant lineages of cephalopods. The other, decabrachians, include modern squid species and cuttlefish, which have 10 arms and two tentacles. 

There are several ways that researchers can tell squid and octopuses apart other than their arms, but the authors of the Nature Communications paper say it was surprising that the fossil had 10 limbs (like a squid) but had other traits characteristic of vampyropods, according to the Times. Those included the lack of a phragmocone—an internal shell used to regulate buoyancy found in other cephalopods, including the nautilus. They found that S. bideni’s inner shell is instead a gladius, a shell-like remnant found in both vampire squids and squids. “We knew we were looking at an early vampyropod,” Whalen tells the Times. 

See “What Scientists Learned by Putting Octopuses in MRI Machines

Some scientists have reservations about the conclusions of the new paper. Christian Klug, a paleontologist at the University of Zurich in Switzerland who was not involved in the work, tells the Times that the specimen most likely represents a known species of ancient cephalopods, the phragmocone-bearing Gordoniconus beargulchensis, that existed around the same time as S. bideni. “It’s the exact same size, the exact same age, the exact same locality, the exact same proportions and it’s just preserved a little bit differently,” Klug explains to the Times. 

The researchers used mostly visual methods of analysis in the new study. Clements tells the Times that the questions Klug raises could be resolved through chemical analyses. “With a full suite of techniques, we would definitely have more clues or a lot more answers,” he says, adding that chemical techniques can be expensive.

Still, the study lends credence to a longstanding hunch among researchers in the field, who suspected that the octopus’ ancient relatives had 10 arms, according to CNN. Now, they have direct proof. 

“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,” Whalen said in a statement provided to CNN.