The group of scientists had plenty of brainpower, able to identify a prehistoric shark tooth or a crocodile jaw with a casual glance.

But when you get right down to it - down being the operative word - paleontology is sometimes a matter of muscles.

Squatting in a muddy Gloucester County mine pit Wednesday afternoon, seven strong men grunted and strained and heaved until they managed to lift up their prize: a 65 million-year-old sea turtle.

"It's beautiful," said a weary, dirt-caked Ken Lacovara, an associate professor of biology at Drexel University.

It was also rare. Lacovara and his colleagues have tentatively identified the creature as Taphrosphys sulcatus, a turtle that lived when much of New Jersey was underwater. Measuring more than three feet across, the specimen is believed to be the largest of its kind yet found.

Unlike box turtles and other North American varieties of today, it did not retract its head straight back into its shell, telescope-style. Instead, it was a side-necked turtle, so called because it folded its head sideways.

Lacovara often travels to distant lands in search of fossils - Egypt, Argentina, and China, to name a few - but he maintains a special place in his heart for southern New Jersey. The pit where his team found the turtle, in particular, has been a rich source of prehistory, allowing scientists to peer back to a time when the earth was free of ice, shrouded in heat-trapping greenhouse gases. If you thought Wednesday was hot, the late Cretaceous period was hotter. Temperature estimates vary, but the New Jersey coast was lush with mangroves.

The pit is owned by Inversand Co. and is mined for a greenish mineral called glauconite, which is used in water-treatment plants. It is in the Sewell area; company officials asked that its exact location not be disclosed because the terrain is treacherous. They have allowed scientists to dig there for decades, primarily from the New Jersey State Museum, Drexel, and the Academy of Natural Sciences.

Representatives from all three were on hand this week, along with volunteers from the 300-member Delaware Valley Paleontological Society, a nonprofit organization that contributed $1,500 to the dig.

The group has found bits and pieces of several creatures this week, including sharks, crocodiles, and a fish sometimes called the saber-toothed herring. All were from 65 million years ago, right when most dinosaurs went extinct.

The turtle, with its unusually large and complete shell, drew the most attention. It began to emerge on Friday, when Drexel Ph.D. student Zack Boles uncovered a quarter of its intricate mosaic shell.

As the team uncovered the rest Monday, "we got excited," Lacovara said.

But the uncovering was just the start of some serious effort.

On Tuesday, shovels were the tool of choice, as the workers cleared away wet muck from around the turtle fossil, digging until it appeared to be raised on a pedestal.

They then encircled the animal's remains in plaster and let it dry overnight.

Wednesday there was still more shoveling, to drain the water that had pooled around the creature.

Inversand plant foreman Steve Ledden, who stopped by the dig site briefly, seemed amused. "They usually come every summer, getting down there and having fun in the dirt," Ledden said of the scientists.

Finally, toward lunchtime, it was time to move the reptilian beast.

Team members inserted a big metal plate underneath the fossil, pounding with stout mallets for more than an hour to get it into position. Then they heaved it onto a wooden stretcher.

"One, two, three!" Lacovara exhorted his colleagues. "Good!"

Shirts and faces became splattered with mud. Muscles glistened with sweat.

At last, it was time to lift.

The seven men staggered as they carried their burden toward a gray Chevrolet pickup. It was no easy feat, as the fossil was encased in wet mud and plaster.

The load easily weighed several hundred pounds, said Jason Schein, an assistant curator of natural history at the New Jersey State Museum.

Now comes the painstaking scientific work to prepare it for study and eventual display.

Paul Ullmann, a Drexel Ph.D. candidate, said several features led him to think the turtle was a Taphrosphys, including the ridged, pebbly texture of its shell surface.

That's a reasonable conclusion, said Tyler Lyson, a Yale University paleontologist who specializes in ancient turtles but was not involved with the New Jersey dig. After looking at an e-mailed photo of the fossil, Lyson said there was little else the creature could be, unless by some chance it turns out to be a new species.

Taphrosphys sulcatus was first found in 1865 by Joseph Leidy, a giant of American paleontology who also identified the first substantially complete dinosaur skeleton. That creature, also found in New Jersey, in Haddonfield, was named Hadrosaurus foulkii.

Lacovara plans to keep coming back to the Gloucester County pit as often as he can this summer, as company officials say the site may be developed soon.

For now it remains a window into the past, with different-colored layers of sediment representing various time periods of long ago: pale yellow, cocoa-brown, and finally, at the bottom of the pit, grayish-green glauconite - the layer that yielded the turtle.

A laboratory for science, and not a bad place for a muscle workout, too.