From Arctic Soil, Fossils of a Goliath That Ruled the Jurassic Seas

By John Noble Wilford

New York Times

An illustration of a pliosaur, with its crushing bite force, on attack. Photo: Atlantic Productions

An illustration of a pliosaur, with its crushing bite force, on attack. Photo: Atlantic Productions

There were monstrous reptiles in the deep, back in the time of dinosaurs.

They swam with mighty flippers, two fore and two hind, all four accelerating on attack. In their elongated heads were bone-crushing jaws more powerful than a Tyrannosaurus rex’s. They were the pliosaurs, heavyweight predators at the top of the food chain in ancient seas.

Much of this was already known. Now, after an analysis of fossils uncovered on a Norwegian island 800 miles from the North Pole, scientists have confirmed that they have found two partial skeletons of a gigantic new species, possibly a new family, of pliosaurs.

This extinct marine reptile was at least 50 feet long and weighed 45 tons, the largest known of its kind. Its massive skull was 10 feet long, and the flippers, more like outsize paddles, were also 10 feet. The creature — not yet given a scientific name but simply called the Monster or Predator X — hunted the seas 150 million years ago, in the Jurassic Period.

“Everything we are finding is new to science,” said Jorn H. Hurum, a paleontologist at the University of Oslo who directed the excavations on the Arctic island of Spitsbergen in the Svalbard archipelago. He described new details of the find in a telephone interview last week.

Dr. Hurum said that in the Jurassic Period, Spitsbergen was covered by the then-temperate waters of a deep ocean. In 2006, the expedition began finding a variety of marine fossils, including pieces of the pliosaur skull, weathering out of a mountainside patrolled by polar bears. A year later, the university announced, the team came upon a flipper and much of the first pliosaur specimen.

But only after excavating the second specimen in last summer’s expedition and comparing the two were the scientists prepared to describe their findings about the huge pliosaur’s anatomy and probable physiology and hunting strategy. This was reported in recent science meetings, and Dr. Hurum said a full description would be published next year in a journal.

two-hour documentary on the expedition will be shown on the History Channel on March 29, at 8 p.m. Eastern and Pacific time.

Fossil hunters get used to working in the heat and cold, the dry and wet, but even without counting the polar bears nosing around their dig, Spitsbergen posed unusual challenges. It has only a three-week window for excavating, from the end of July through much of August.

That is after the warmth of a brief summer has thawed upper layers of the ground and before the onset of the round-the-clock darkness of Arctic winter. Even on the better days, temperatures drop close to freezing and clouds often spring a leak. For hours on end, excavators are assaulted by deafening jackhammers penetrating the recalcitrant permafrost to reach lower fossil beds. They are left in no doubt as to why, until now, Spitsbergen’s fossils had gone largely untapped.

Pliosaurs were marine reptiles not directly related to dinosaurs, which dwelled on land. Previous well-studied discoveries in Australia and England showed the average length of pliosaurs to be 16 to 20 feet. An Australian giant, Kronosaurus, measured up to 36 feet. In 2002, European and Mexican scientists found bones of what they called a larger pliosaur, but paleontologists said that much more analysis of the fossils was required before its size could be reliably estimated.

Pliosaurs preyed on fish, squidlike animals and other marine reptiles, including smaller relatives, the long-necked pleisosaurs, and another common sea reptile, ichthyosaurs, which superficially resemble the modern dolphin. Bones of many of these species have been collected at the Spitsbergen site.

Patrick Druckenmiller, a paleontologist at the University of Alaska, Fairbanks, and a member of the expedition, said the archipelago was proving to be “one of the most important localities of extinct marine reptiles in the world.”

Recent examinations of the Spitsbergen fossils were conducted at the Natural History Museum in Oslo, and in London and the United States. Bones at the base of the animal’s skull and in the jaw enabled researchers to estimate the 10-foot length of its crocodile-like head.

At Duke University, American scientists conducted wind-tunnel tests on models of the animal’s flippers, trying to determine how they were used to move through the water. Calculations of their hydrodynamic properties, researchers said, suggested that the predator could have used the front flippers while cruising, but went into overdrive with all four to accelerate toward its prey.

At the Natural History Museum in London, scientists took CT scans of the pliosaur’s skull, especially the region of the braincase, measuring its probable brain size and shape.

Although the recovered braincase was not complete, Dr. Druckenmiller, who participated in the CT examination, said that some of the structure appeared to be “similar in many respects” to the great white shark, the top predator in oceans today.

Dr. Hurum, therefore, suggested that the pliosaur might have been comparable to the white shark “in hunting strategy but much more powerful.”

In another investigation, Gregory M. Erickson, an evolutionary biologist at Florida State University, compiled data on the bite force of crocodiles and large alligators. A summary of results, issued by Dr. Hurum’s team, said the research indicated that the much larger Predator X had a bite force of about 33,000 pounds — more than 10 times that of any animal alive today and 2 to 4 times the bite force of T. rex.

“There is nothing really comparable in the sea today,” Dr. Hurum said, as he looked forward to more digging in August, in the remaining daylight of Spitsbergen’s next brief thaw.

Source: New York Times

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