Evolution: very early octopus fossil (Evolution)

by David Turell , Wednesday, November 08, 2023, 19:30 (170 days ago) @ David Turell

From 330 million years ago:

https://phys.org/news/2022-03-octopus-ancestors-era-dinosaurs.html

"Scientists have found the oldest known ancestor of octopuses – an approximately 330 million-year-old fossil unearthed in Montana.

"The researchers concluded the ancient creature lived millions of years earlier than previously believed, meaning that octopuses originated before the era of dinosaurs.

"The 4.7-inch (12-centimeter) fossil has 10 limbs—modern octopuses have eight—each with two rows of suckers. It probably lived in a shallow, tropical ocean bay.

"'It's very rare to find soft tissue fossils, except in a few places," said Mike Vecchione, a Smithsonian National Museum of Natural History zoologist who was not involved in the study. "This is a very exciting finding. It pushes back the ancestry much farther than previously known." (my bold)

***

"The creature, a vampyropod, was likely the ancestor of both modern octopuses and vampire squid, a confusingly named marine critter that's much closer to an octopus than a squid. Previously, the "oldest known definitive" vampyropod was from around 240 million years ago, the authors said.

"More information: https://evolutionnews.org/2023/11/will-the-octopus-ever-find-its-place-in-the-evolution...

"A detailed genetic analysis found that the common octopus has 2.8 billion base pairs of genes:

"To gain a deeper understanding of their biology and evolutionary history, validated data on the composition of their genome is needed, which has been lacking until now. Scientists from the University of Vienna together with an international research team have now been able to close this gap and, in a study, determined impressive figures: 2.8 billion base pairs — organized in 30 chromosomes.

***

“'There are tens of thousands of both chemical and mechanical receptors in each sucker,” he says. “To put that into perspective, each of your fingertips has a few hundred mechanical receptors.”
The team found that if one of an octopus’ suckers finds something interesting, like food, it triggers a sucker next to it to double check. If that sucker is also interested in the potential treat, it triggers the next one. This creates a cascade of neurons down the arm’s ganglia (nerve cell clusters), encouraging the octopus’ arm to then wrap around the item of interest.

"This entire process bypasses the animal’s brain—but the system isn’t perfect. Because the suckers can act independently of the brain there’s not always consensus, Sivitilli explains. “Sometimes, the arm plays tug of war with itself,” he says.

***

"Another factor that may be linked to high cephalopod intelligence is gene editing:
A team of scientists led by Joshua Rosenthal at the Marine Biological Laboratory and Eli Eisenberg at Tel Aviv University have shown that octopuses and their relatives — the cephalopods — practice a type of genetic alteration called RNA editing that’s very rare in the rest of the animal kingdom. They use it to fine-tune the information encoded by their genes without altering the genes themselves. And they do so extensively, to a far greater degree than any other animal group.

***

"[Tamar] Gutnick and his colleagues were able to pick up clear signals of brain activity, but deciphering these patterns is another story. Some of the brain waves resembled the size and shape of mammalian brain activity, but other pulses from the neurons of octopuses were completely bizarre. These were long-lasting, slow oscillations with large amplitudes, which indicates relatively strong electrical activity. These have not been reported before.

"Unfortunately, the researchers were unable to find a strong correlation between this activity and the way the octopuses were behaving. Even when the octopuses were moving around, they could find no obvious changes in signal, despite drastic changes in motion or remaining still.

Comment: totally weird. Note my bold concerning the rarity of soft bodied organisms. We still do not know the octopus predecessors. This is still a problem 'gap'. We need more fossils.