They're here.

"The World's Largest Dinosaurs" has opened, the first of 20 exhibits from the American Museum of Natural History to be displayed in Overland Park's Prairiefire development during the next decade.

The $23 million Museum of Prairiefire is still under construction and won't open till May. So the dinosaur exhibit has been set up in temporary space just west of the museum's permanent location, 6285 W. 135th St.

Hours will be 10 a.m. to 7 p.m. Monday through Saturday and noon to 6 p.m. Sundays until Jan. 2. Tickets to the exhibition, available online at www.museumofpf.org, are $10 for adults and $5 for children 12 and younger.

Mark Norell, chairman of the AMNH's division of paleontology and curator of the exhibit, said it explores the amazing biology of a group of super-sized dinosaurs, the long-necked and long-tailed sauropads. Drawing on paleo-biological research, Norell said, his goal was to portray dinosaurs as the "living, breathing animals" they were and give viewers an idea of "how much they ate, how their hearts worked, how their brains worked."

Norell was on hand Oct. 7 for an invitation-only preview of the exhibit that was attended by Kansas Lt. Gov. Jeff Colyer; Steve Kelly, deputy secretary of the Kansas Department of Commerce; Ed Eilert, chairman of the Johnson County Board of Commissioners; dozens of Overland Park elected officials and staff members; and patrons and board members of the Prairiefire Museum.

They were introduced and thanked for their support by Prairiefire developer Fred Merrill and his wife, Candy. Merrill began working on the 58-acre, $427 million mixed-use development seven years ago.

Merrill put the development site, south of 135th Street between Nall and Lamar avenues, under contract in 2006 with the idea that it should include a significant civic attraction.

Then the recession hit, and the project was put on hold but during the delay, Merrill learned that the American Museum of Natural History wanted to expand its brand. In 2008, he reached a deal allowing Prairiefire to host a steady stream of exhibits from the museum. And that helped land $81 million in Kansas sales tax revenue, or STAR, bond financing, which allows portions of tourism-related projects to be paid for using the state sales tax they generate.

If the success of the AMNH is any indication, Norell said, the result should be a significant tourism boom for Overland Park and Kansas.

"We are second only to Disneyland among top family tourist attractions in the whole United States," Norell said of the New York City museum. "More than 5 million people visit each year."

The AMNH exhibit on display at Prairiefire just arrived from Paris, Norell added, and will travel from Overland Park to the Perot Museum of Nature and Science in Dallas.

Eventually, it will be replaced at the Prairiefire museum with a permanent dinosaur exhibit - a duplicate of the Tyrannosaurus rex skeleton that stars in the movie "Night at the Museum."

The fossilized T Rex was discovered in 1902 in Montana by Carbondale, Kan., native and University of Kansas graduate Barnum Brown, who was named after circus showman P.T. Barnum.

Norell, who holds the same AMNH job that Brown once held, has co-written a book about the famous dinosaur hunter, "Barnum Brown: The Man Who Discovered Tyrannosaurus Rex."

"Indiana Jones was patterned after Barnum Brown," Fred Merrill said.

Brown, who died at age 90 in 1963, discovered dozens of dinosaur species - and quite a bit of oil -while scouring every corner of the globe. According to Norell, Brown lived fast, dressed to the nines, gambled, drank, smoked and was known as a ladies' man. He spied for the U.S. government under cover of his expeditions between the world wars, Norell said, and in that capacity once had an affair with a German ambassador's wife.

The sauropod exhibit at Prairiefire reveals an interesting past of another kind.

The star of the exhibition is a life-sized model of an 18-year-old, 60-foot-long, 11-foot-tall female Mamenchisaurus. Visitors will discover how she looked in life and how she would have looked had scientists been able to peer inside her body.