Mark McMenamin
A giant sea monster, the likes of the mythological kraken, may have taken out ichthyosaurs the size of school buses, arranging their vertebrae in curious linear patterns with nearly geometric patterns (shown here). The arranged vertebrae resemble the pattern of suckers on a cephalopod's tentacle.
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updated 10/11/2011 2:10:23 PM ET 2011-10-11T18:10:23

A giant sea monster, the likes of the mythological kraken, may have swum Earth's ancient oceans, snagging what was thought to be the sea's top predators — school bus-size ichthyosaurs with fearsome teeth.

The kraken, which would've been nearly 100 feet (30 meters) long, or twice the size of the colossal squid Mesonychoteuthis, likely drowned or broke the necks of the ichthyosaurs before dragging the corpses to its lair, akin to an octopus' midden, according to study researcher Mark McMenamin, a paleontologist at Mount Holyoke College in Massachusetts. [Rumor or Reality: The Creatures of Cryptozoology]

"It is known that the modern octopus will pile the remains of its prey in a midden and play with and manipulate those pieces," McMenamin said during a telephone interview.

There is no direct evidence for the beast, though McMenamin suggests that's because it was soft-bodied and didn't stand the test of time; even so, to make a firm case for its existence one would want to find more direct evidence.

"No direct evidence of large cephalopods, in fact very little data at all, is problematic for proposing such a radical explanation," Glenn Storrs, curator of vertebrate paleontology at Cincinnati Museum Center, told LiveScience in an email. "Circumstantial evidence is not enough."

Storrs added, "On top of this, the specimens are not well preserved in their current setting, thus the arrangement, 'etching' and bone breakage may have alternate explanations. To my mind, this hypothesis is like looking at clouds — being able to see what you desire."

McMenamin presented his work Monday at the annual meeting of the Geological Society of America in Minneapolis.

Cause of death
Evidence for the kraken and its gruesome attacks comes from markings on the bones of the remains of nine 45-foot (14 meter) ichthyosaurs of the species Shonisaurus popularis, which lived during the Triassic, a period that lasted from 248 million to 206 million years ago. The beasts were the Triassic version of today's predatory giant squid-eating sperm whales.

McMenamin was interested in solving a longstanding puzzle over the cause of death of the S. popularis individuals at the Berlin-Ichthyosaur State Park in Nevada. An expert on the site, Charles Lewis Camp of the University at California at Berkeley, suggested in the 1950s that the ichthyosaurs succumbed to an accidental stranding or a toxic plankton bloom. However, nobody has been able to prove that the beasts died in shallow water. More recent work on the rocks around the fossils by Jennifer Hogler, then at the University of California Museum of Paleontology, suggested that they died in a deepwater environment.

"I was aware that anytime there is controversy about depth, there is probably something interesting going on," McMenamin said. And when he and his daughter arrived at the park, they were struck by the remains' strangeness, particularly "a very odd configuration of bones."

The etching on the bones suggested the shonisaurs were not all killed and buried at the same time, he said. It also looked as if the bones had been purposefully rearranged, likely carried to the "kraken's lair" after they had been killed. A similar behavior has been seen in modern octopus.

The markings and rearrangement of the S. popularis bones suggests an octopus-like creature (like a kraken) either drowned the ichthyosaurs or broke their necks, according to McMenamin.

The arranged vertebrae also seemed to resemble the pattern of sucker disks on a cephalopod's tentacle, with each vertebra strongly resembling a sucker made by a member of the Coleoidea, which includes octopuses, squid, cuttlefish and their relatives. The researchers suggest this pattern reveals a self-portrait of the mysterious beast.

Dmitry Bogdanov
The ichthyosaur, Shonisaurus popularis, was a school bus-size predatory reptile thought to rule the Triassic seas.

The perfect crime?
Next, McMenamin wondered if an octopus-like creature could realistically have taken out the huge swimming predatory reptiles. Evidence is in their favor, it seems. Video taken by staff at the Seattle Aquarium showed that a large octopus in one of their large tanks had been killing the sharks. [On the Brink: A Gallery of Wild Sharks]

"It would have been very similar to the way that the Pacific Octopus was killing sharks at the Seattle Aquarium, the main difference being that the animals were scaled up to enormous size," McMenamin told LiveScience, adding that "ichthyosaurs are air breathers and can be drowned."

More supporting evidence: There were many more broken ribs seen in the shonisaur fossils than would seem accidental, as well as evidence of twisted necks.

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"It was either drowning them or breaking their necks," McMenamin said.

So where did this kraken go? Since octopuses are mostly soft-bodied they don't fossilize well, and scientists wouldn't expect to find their remains from so long ago. Only their beaks, or mouthparts, are hard, and the chances of those being preserved nearby are very low, according to the researchers.

With such circumstanial evidence of "the crime," McMenamin expects his interpretation will draw skeptics. And, in fact, it has. Brian Switek, a research associate at the New Jersey State Museum, writing for Wired.com, is extremely skeptical, writing, "The McMenamins' entire case is based on peculiar inferences about the site. It is a case of reading the scattered bones as if they were tea leaves able to tell someone’s fortune. Rather than being distributed through the bonebed by natural processes related to decay and preservation, the McMenamins argue that the Shonisaurus bones were intentionally arrayed in a 'midden' by a huge cephalopod nearly 100 feet long." (McMenamin worked with his wife, Dianna Schulte McMenamin on the study.)

As for how McMenamin would respond to critics: "We're ready for this. We have a very good case," he said.

Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.

© 2012 LiveScience.com. All rights reserved.

Explainer: Ten of nature's scariest animals

  • Stephen Chernin  /  AP file

    Humans seem to love a good scare, particularly on Halloween. Ghosts, zombies, vampires and other fictional characters are good for putting a chill down your spine. But if you're looking for something truly scary, let nature be your guide. Click on the "Next" label to see 10 of the animal world's scariest creatures.

  • Box jellyfish pack a deadly sting

    Anders Garm

    The box jellyfish is ghostly and squishy, with 24 eyes and a tangle of tentacles, each equipped with about 5,000 stinging cells. The creatures pack a special type of venom — the most deadly in the animal kingdom — that is activated by contact with certain chemicals found in fish, shellfish and humans. The venom can cause cardiac arrest, cripple the nervous system, and eat away skin. Several victims stung at sea die before they reach shore.

  • Black mamba: Speedy snake with lethal venom

    Eric Marquette

    Even people who are fearless around snakes should be careful in the presence of a black mamba. Native to sub-Saharan Africa, the territorial and aggressive snakes grow up to 14 feet long and travel at speeds of more than 12 miles per hour. Fortunately, black mambas are shy and usually race away when humans approach. But when threatened, they attack with repeated strikes to deliver lethal venom. Only a quickly administered antidote saves victims from death. The black mamba gets its name from the color of the inside of its mouth, seen here.

  • Saltwater crocodiles eat people

    Greg Wood  /  AFP - Getty Images

    Saltwater crocodiles are aggressive and territorial. And unlike their North American alligator cousins, they regularly eat people. They live in saltwater estuaries, and freshwater rivers and swamps, ranging from Australia north to Southeast Asia. The biggest males weigh in excess of 2,200 pounds and measure 20 feet from toothy snout to scaly tail, making them the world's largest reptiles. Though they mostly dine on smaller prey such as fish and shorebirds, adults will occasionally tackle larger animals, including careless people. Tourists lure this croc out of the water with a chunk of meat.

  • Polar bears: a poster child best left alone

    USFWS

    Polar bears are a poster child for groups campaigning to save the world from the ravages of global warming. But the cute and cuddly image that polar bears project are an icy disguise. Polar bears are the world's largest land predators; some males top the scales at 1,500 pounds and wield 2-inch-long claws. They normally kill seals and the occasional walrus twice their size. Human attacks are extremely rare but potentially fatal.

  • Wolves are revered and feared

    AP file

    Revered by some, feared by others, the gray wolf is the world's biggest, most powerful dog. Strong jaws and sharp teeth help them rip into their prey. Wolves primarily hunt deer, moose and bison, but when wild supplies are tight, domestic cattle and sheep are easy targets — hence the wolf's uneasy relationship with humans. In the 20th century, the predators were nearly hunted to extinction. Continued fear of the wolf continues to muddy their road to recovery.

  • Lions take a mean bite

    Daniel Munoz  /  Reuters

    In 1898, a pair of lions reportedly ate 135 people working on a railroad in Kenya. Though lions continue to make the occasional human meal, most of the slaughtering now goes the other way. Today, the cats are vulnerable to extinction, due to their human predators. Conservationists are racing to keep the survivors alive. In this image, two lions at a Sydney zoo gaze at each other before a non-human meal.

  • Shark attacks: Very feared, very rare

    Image: Casa Rinconada
    Reuters

    Maybe the 1975 film "Jaws" is to blame, but whatever the cause, many humans are terrified of the great white shark, the largest predatory fish in the ocean. The fear is understandable: These giants have a mouth full of razor-sharp teeth, they can reach 20 feet in length, and they top the scales at 5,000 pounds. Despite all that, scientists insist the predators pose little risk to humans. They say the chances of winning the lottery are higher than the chance of being attacked by a great white. Moreover, most attacks are not fatal. In this image, a great white swims past a cage holding tourists.

  • Scariest spider is a recluse

    Image: Chankillo
    Justin Sullivan  /  Getty Images file

    Tarantulas give lots of people the creeps, but scientists say most of the big and hairy spiders are harmless to humans. The real spider to fear is the brown recluse, a six-eyed spider with a violin-shaped head and a venomous bite that can lead to necrosis — the death of skin tissue. Fortunately, as their name suggests, the spiders are reclusive and seldom aggressive, only biting when threatened. Most bites have little or no effect on their human victims, but some are nasty and even fatal.

  • Mosquitoes kill millions every year

    USDA

    The world's deadliest animal? The mosquito. In some parts of the world, these pesky, bloodsucking insects spread diseases such as malaria, dengue fever and West Nile Virus that kill nearly 3 million people a year. Many of the malaria deaths occur in sub-Saharan Africa, where scientists and international aid organizations are busy developing strategies to stop the disease's lethal spread.

  • Vampire bats feed on blood

    Ho  /  AFP - Getty Images

    Finally, what list of scary animals would be complete without the vampire bat? The thumb-sized flying mammals with eight-inch wingspans feed exclusively on blood in the dark of night. Their prime targets are cattle and horses, but they are known to attack humans, too. Heat sensors in the bat's nose help it find flowing blood. They bite through the skin with razor-sharp teeth and lap up what oozes out.

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