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A new exhibit at The Field Museum examines life in everything from the Precambrian to the Quaternary periods, but it's opening during a period when the theory of evolution is under attack by supporters of so-called "intelligent design."

Museum officials say that the timeliness is a coincidence — work began on "Evolving Planet" four years ago, and it replaces an exhibit that touched on many of the same themes.

But if there is any doubt about where the exhibit falls in the debate, it closes with a quote from Charles Darwin, who concluded that species evolve over time.

The "intelligent design" movement challenges Darwin's theory, contending that organisms are so complex that they must have been created by some kind of higher authority. Critics of intelligent design say it is biblical creationism in disguise.

The museum has prepared for the issue. Docents have received training about how to handle "intelligent design" visitors' challenges to such concepts as natural selection. The museum also will be presenting a reading of "Inherit the Wind," the play based on the Scopes Monkey Trial, which resulted in the conviction of a biology teacher for teaching evolution.

"You can't force somebody to accept evolution. We wouldn't want to do that," said Richard Kissel, a paleontologist who served as the exhibit's content specialist. "But hopefully they'll understand science is a very rigorous process ... where we test these theories day in and day out, and evolution is one that has held up for 100 years."

"Evolving Planet," which opens to the public on Friday, uses 27,000 square feet to examine how life has unfolded on Earth over the course of 4 billion years through the process of evolution. A permanent exhibit, it replaces "Life Over Time," which opened in 1994.

Museum officials felt their presentation of evolution needed a boost — both because of new scientific discoveries in the last decade and because movies such as "Jurassic Park" and programs on the Discovery Channel have created high expectations among museumgoers.

The result is an exhibit that employs animated videos (a shivering cartoon mammoth illustrates the concept of an Ice Age), dramatic lighting and interactive displays to illustrate how life on Earth progressed from single-celled organisms to Homo sapiens.

One high-tech highlight is a huge curved screen that serves as the backdrop for a video projection of what a 500-million-year-old ocean might have looked like.

As the visitor watches, bizarre-looking creatures — most with little resemblance to current underwater animals — swim by.

But the show also includes plenty of examples of an old-fashioned favorite — fossils.

In fact, whereas the previous exhibit featured 600 fossils, about 1,300 specimens are exhibited in "Evolving Planet," including many that have never before been seen publicly.

One fossil taken out of storage is that of a giant short-faced bear, or Arctodus simus. The fossil was found in Indiana, and lived about 12,000 years ago. It measured about five feet tall at the shoulder — making it one of the largest ever land-based mammalian carnivores — and was 12 feet tall when rearing up on its hind legs, as it is shown at the Field. It has much longer legs than today's bears, and could probably run quickly.

"It was the biggest predator of the Ice Age. This was the king, the T. rex of the Ice Age," said Kissel.

The Field Museum, of course, is home to a real Tyrannosaurus rex. Nicknamed Sue, it is the largest and most complete T. rex fossil yet discovered. Sue will remain in her current location in the museum's elegant neoclassic entrance hall.

But "Evolving Planet" has its own gigantic "dinosaur hall," featuring representatives of every major dinosaur group, including both adult and juvenile versions of sauropods, the long-necked plant eaters that were the largest animals ever to walk the Earth.

A nearly complete fossil of a carnivorous Daspletosaurus is shown posed over its prey, a duckbilled dinosaur. And a fossil of the raptor Deinonychus is used to tell the story of how scientists believe dinosaurs evolved into birds.

The exhibit ends with a warning about how the Earth is currently in one of its "mass extinction" periods — with one species going extinct approximately every 15 minutes. Human causes are to blame for many of the disappearances, said Todd Tubutis, the show's project manager.

But first, visitors pass through a section on the origins of Homo sapiens, examining the wide array of the small human ancestors known as hominids.

It features a life-sized reconstruction of "Lucy," one of the oldest members of the human family. The nearly complete fossil was discovered in Ethiopia in 1974. About 4 feet tall, the Field's depiction of "Lucy" shows her walking upright, with a chimpanzeelike face and a light coat of hair over her body.

Such a depiction is sure to annoy evolution opponents. Yet organizers of the exhibit say surveys show the vast majority of visitors to natural history museums believe in evolution before they enter the doors.