Welcome to the complete paleo-experience (courtesy of the Smithsonian's National Museum of Natural History). No more trooping over to one hall to see the paleobotanical forerunner of ferns and then trooping over to another to view the amphibians.

To show that the evolution of animals, from the earliest amphibians to those that now stalk the earth, was related to the evolution of plants, from minimal foliage (mostly stem) to the resplendent flowering types on Dupont Circle window sills, hundreds of fossils and models have been collected into one permanent hall -- "The Conquest of Land" exhibit.

The hall opens today, although some work will continue. Eventually, you will stand in the great (60 feet high) dinosaur room, on the same level with the dinosaurs ("instead of having them on pedestals," said associate curator Leo Hickey). Yesterday, as welding continued, the dinosaurs were under thick, transparent wraps, standing over a buffet and grand piano, all assembled for a celebration of the opening of this hall.

Up the ramp from the dinosaur room will be the beginnings of land animals and the "conquest of land." (Imagine you are an amphibian following the evolutionary route . . .)

Among the displays are a free-standing amphibian (behind glass), an early fossilized tree -- 15 feet high and flattened after years of lying in a bed of rock in the Oklahoma ground -- and giant dinosaur and ostrich eggs.

One of the most dramatic exhibits, mounted in the floor, shows the remains of amphibians that were unable to evolve to land. They trashed and ripped at each other in a frenzy as their pond dried up. Unfortunately, one must read the text and look at this maze of fossils very hard before the eye figures out what happened. It helps to take a scientist along to these exhibits.

The hall houses about two-thirds new material never before exhibited in the museum. A committee of seven museum scientists put it all together, and they know a lot about the collecting of such items.

"If you look in the right area, you can find a dinosaur," said Leo Hickey, who has spent his share of time collecting them in the swamp sediments of Montana, near rivers. "You can find a horn of the tricerotops (which has a shield and three horns."

"I've found pounds of them north of Calgary in Canada," said Ian Macintyre, a staff geologist at the museum who regularly went looking for them when he was working for an oil company."I was always hoping to find a tooth."

Actually, finding a fragment in a western badland in this country is not unusual -- what's more difficult and more expensive is finding enough pieces to put together some kind of a skeleton.

Neither Macintyre nor Hickey advises people to dig up the fragments they do find. "If you find a dinosaur, and you can't use it, leave it," said Hickey.

"Or call a museum," said Macintyre.

Most digging should be left to the professionals who can accurately identify what they're digging up and how old it is, they said.