Tuesday, October 11, 2011

Kraken? Hints of a Giant Triassic Octopus

Paleontologist Mark McMenamin was wondering about the famous Ichthyosaur remains from Berlin-Ichthyosaur State Park in Nevada, where nine 45-foot (14 m) specimens of the species Shonisaurus popularis have been found. Why did so many die together? Perhaps, others had thought, they were beached after a deadly red tide. But the rocks suggest they died in deep water, and there were other problems:
"It became very clear that something very odd was going on there," said McMenamin. "It was a very odd configuration of bones."

First of all, the different degrees of etching on the bones suggested that the shonisaurs were not all killed and buried at the same time. It also looked like the bones had been purposefully rearranged. That it got him thinking about a particular modern predator that is known for just this sort of intelligent manipulation of bones.

"Modern octopus will do this," McMenamin said. What if there was an ancient, very large sort of octopus, like the kraken of mythology. "I think that these things were captured by the kraken and taken to the midden and the cephalopod would take them apart. . . . "

But could an octopus really have taken out such huge swimming predatory reptiles? No one would have believed such a tale until the staff of the Seattle Aquarium set up a video camera at night a few years ago to find out what was killing the sharks in one of their large tanks. What they were shocked to discover was that a large octopus they had in the same tank was the culprit. The video of one of these attacks is available on the web to anyone who uses the search terms "shark vs octopus."

"We think that this cephalopod in the Triassic was doing the same thing," said McMenamin. Among the evidences of the kraken attacks are many more ribs broken in the shonisaur fossils than would seem accidental and the twisted necks of the ichthyosaurs. "It was either drowning them or breaking their necks."

Of course, it's the perfect Triassic crime because octopuses are mostly soft-bodied and don't fossilize well. Only their beaks, or mouth parts, are hard and the chances of those being preserved nearby are very low. That means the evidence for the murderous Kraken is circumstantial, which may leave some scientists rather skeptical. But McMenamin is not worried.

"We're ready for this," he said. "We have a very good case."

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