Thursday, November 21, 2013
Thursday, November 14, 2013
Kraken Sea Monster : A recent fossil find is renewing interest in the search for the ancient giant cephalopod known as the kraken.
The idea of a kraken was originally proposed a couple of years ago at the meeting of the Geological Society of America by Mount Holyoke College palaeontologist Mark McMenamin.
Now he has returned to the annual meeting with what he believes is more evidence of the kraken, including what could be the tip of its tooth-like beak, another example of a potential kraken murder case, and the earliest-known fossil of a scavenger crustacean that is today among those found devouring whale carcasses in the ocean depths.
The initial evidence for the kraken was very indirect.
In 2011, McMenamin found signs that the remains of 14-metre ichthyosaurs at Nevada's Berlin-Ichthyosaur State Park were arranged in patterns that resembled the work of a modern-day octopus - which are known to fiddle and arrange bones as well as attack and kill sharks.
He also asserted then, as now, that the Nevada rocks in which the ichthyosaurs were found are incorrectly interpreted as being made from shallow ocean sediments, when they are actually from much much deeper.
The kraken hypothesis was not warmly embraced by his colleagues, and McMenamin was going to let the matter drop until he came across an old issue of a journal in which there were photos of a museum display of the ichthyosaurs skeletons that had been removed from the park.
"It was laid out exactly as found in the field and there were rib cage constrictions," says McMenamin. "It was very strange. I'd never seen anything like it before. It looked like something had pulled bones out of place and placed them to one side."
So McMenamin returned earlier this year to Nevada with students in search of additional evidence. What they found was a small rock that they later realised might be part of a giant cephalopod beak - a kraken's maw.
"It's the densest thing on the body of a cephalopod," says McMenamin. And so it's the most likely thing to be preserved in the fossil record. "We obtained a beak of a giant Humboldt squid and compared. That actually worked pretty well. We have direct comparison to modern Humboldt squid. They had very similar fractures and converging straia (lines)."
These are just more pieces in the kraken case, which is a tough one, as there are other explanations for the evidence.
"The problem with the kraken argument is it does not take into account all the other ways those vertebrae could have been re-arranged," says Spencer Lucas, palaeontologist and curator at the New Mexico Museum of Natural History and Science.
"For example, the body of the ichthyosaur had to decompose and collapse, and scavenging by various animals could have taken place. These processes could have rearranged vertebrae."
Several experts in the area were also asked to comment, but said they preferred not to. Still even Lucas isn't ruling a kraken out.
"I suppose the kraken argument is a possibility, but one of many, and a highly unusual one. What we need here is a more rigorous analysis that excludes the many alternatives to the kraken idea."
On the other hand, there is that scavenger fossil - what's called an amphipod - that was found by one of McMenamin's students. He's giving a second presentation about that find at the same meeting, arguing that it's the earliest known and a supergiant version of today's small crustaceans.
That's a much easier case to make, and important to palaeontologists, if not as racy as a kraken.
"The amphipod is an important addition to our knowledge of a group with a limited fossil record," says Lucas.