Back in the Triassic, giant octopi were killing and eating ichthyosaurs - and arranging their bones in pretty patterns, says a Mount Holyoke College paleontologist.
The remains of nine 45-foot Shonisaurus popularis were discovered more than 50 years ago, at the at Berlin-Ichthyosaur State Park in Nevada, and have been puzzling paleontologists ever since.
The assumption has always been that the fossils probably represented death by an accidental stranding or from a toxic plankton bloom - but recent research has cast doubt on this theory by suggesting that the creatures died in deep water.
And, says Mark McMenamin, the strangeness doesn't end there.
"It became very clear that something very odd was going on there," he says. "It was a very odd configuration of bones."
First of all, the different degrees of etching on the bones suggested that the Shonisaurus weren't all killed and buried at the same time. Even more weirdly, it appeared that the bones had been purposefully rearranged, with some of the shonisaur vertebral disks organised in curious linear patterns with almost geometric regularity.
And, says McMenamin, there is one modern predator that does exactly this - the octopus. He suggests that the remains may indicate the existence of a giant octopus, similar to the Kraken of kegend.
"I think that these things were captured by the kraken and taken to the midden and the cephalopod would take them apart," he says.
Octopi are better fighters than one might imagine - there's a YouTube video of one taking out a shark at the Seattle Aquarium, here.
"We think that this cephalopod in the Triassic was doing the same thing," says McMenamin. "It was either drowning them or breaking their necks."
As for the arrangement of vertebrae, McMenamin has a pretty way-out explanation. He suggests that the patterns may represent the earliest self-portrait ever discovered.
The arranged vertebrae resemble the pattern of sucker discs on a cephalopod tentacle, he says, with each bone representing a coleoid sucker.
Unfortunately, though, it's a hypothesis that will be hard to back up. Octopuses are mostly soft-bodied and don't fossilize well. Only their beaks are hard, and the odds of these being preserved nearby are very low.
But, says McMenamin, "We're ready for this. We have a very good case."