Canada’s first apex predator, the anomalocaris canadensis, may not have been the fearsome creature its looks imply. What was once considered ‘Earth’s first great predator’ was not as ferocious as was previously believed. – Global Animal

This image from WWW.NaturalHistoryExplorer.com depicts the Anomalocaris Canadensis chasing trilobites that were onced believed to be it's prey.

Postmedia News, Randy Boswell

A new study appears to have defanged the nasty-looking beast that has long been considered the first apex predator of ancient Canada.

Anomalocaris canadensis, an extinct, 500-million-year-old marine creature best known to scientists from the world-famous Burgess Shale fossil deposit in eastern British Columbia, has traditionally been placed at the top of the Cambrian-era food chain as the seabed-stalking, trilobite-chomping, dominant species of its time.

But using 3-D digital modelling of the animal’s teeth and mouth structure, a Colorado researcher who examined 400 anomalocaris specimens around the world has concluded that the metre-long monster’s bite wasn’t strong enough to crack through the exoskeletons of its purported prey.

“It was supposed to roam around the Cambrian seas, gobbling up trilobites and everything else,” researcher James Hagadorn, a paleontologist at the Denver Museum of Science and Nature, states in a summary of findings to be detailed at a U.S. geology conference this week.

But his computer-aided analysis of the animal’s teeth and mouth area suggested anomalocaris “couldn’t even close its mouth.”

Hagadorn’s probe also turned up no evidence of scratches or other signs of wear and tear on the fossilized specimens’ teeth — something that would be expected for a predator that feeds by pulverizing the hard parts of its prey’s anatomy.

“There was no practical way these mouth parts could create the force needed to break open a modern lobster shell nor a shrimp shell, which were used as analogs for a trilobite carapace in the model,” states the summary, issued Monday by the Geological Society of America, which concluded: “Earth’s first great predator wasn’t.”

Anomalocaris canadensis (which translates from the Latin as “abnormal Canadian shrimp”) is one of the signature species of the Burgess Shale, a showcase part of a UNESCO World Heritage site straddling the B.C.-Alberta border in the Canadian Rockies.

Last year, when Canadian paleontologists celebrated the 100th anniversary of the fossil bed’s discovery in 1909 by U.S. scientist Charles Doolittle Walcott, the “Shale Ale” commemorative beer brewed for the occasion prominently featured a picture of Anomalocaris on the label.

Anomalocaris is notable for its bulging eyes and dual, segmented appendages protruding from its head like two elephants’ trunks.

Its circular mouth has been described as having a pineapple-like patterning of sharp teeth that could cut through the outer shells of trilobites and other crunchy creatures that emerged during evolution’s so-called “Cambrian explosion” of animal life about a half-billion years ago.

“But the pineapple-like whorl of mouth parts and the associated whisker-like appendages of Anomalocaris all appear to have been bendable, in the fossil remains,” Hagadorn’s study has determined. “They are not mineralized like the exoskeletons of the trilobites they were supposedly eating.”

Several lines of evidence, Hagadorn said, point to the same conclusion: that the allegedly ferocious hunter from Cambrian Canada was not, in fact, crushing large prey with a viselike bite.

“The model, gut contents, feces and wear all suggest Anomalocaris was not a trilobite eater,” the U.S. study has found. “But they fail to help explain what this impressive beast from the Cambrian was eating,” or exactly how it ingested the bodies of its victims.

“At this point, the only thing that appears certain is that the famed biggest predator of the early Cambrian is more mysterious than ever.”

http://www.vancouversun.com/life/eat-drink/Study+takes+bite+creature+fearsome+reputation/3762851/story.html#ixzz14SJtyu1M

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