It was 10 p.m.. The tourists had gone home and the dinosaur hall on the fourth floor at the American Museum of Natural History glowed with an eerie red light.
Nine-year-olds Jack Welsh and Lylah Rutigliano, of Demarest, N.J., peered at a giant skeleton with their flashlight.
"Look at its teeth," said Jack, who pointed to a large jaw hanging from the ceiling. "Oh my gosh, he didn't have to chew anything. He could've just been like, put us in his mouth and we're gone."
Jack and Lylah, in fact, were alone with the dinosaurs and if these creatures came to life at night, a question that children and adults alike have pondered with fascination, then the two would be dead meat.
But all was calm at the museum, except for the hundreds of youngsters and their chaperones, who swarmed around the ancient fossils. After 20 years, the museum started opening up its doors in January to kids and their parents for a sleepover program filled with activities and late-night roams around the halls.
"It's a great way to introduce the children to the museum, to science," said Brad Harris, senior director for visitor services at the American Museum of Natural History. "It's a fun way to do it, and it's a great way to raise funds for the museum."
The doors opened at around 6 p.m. and there was a host of activities for the kids to do.
But for many of the 465 explorers who ventured to the museum's nocturnal excursion, the highlight was sleeping under the giant blue whale in the Milstein Hall of Ocean Life.
The life-size replica of the beloved marine mammal is featured in films and is a major museum destination for kids.
"I feel like I'm in the ocean," one boy said to his companion as they set up their cot.
While some made their camp at sea, others made their way over to a butterfly exhibit. Winged creatures landed on visitors' shoulders and sucked nectar from flowers.
"Butterflies are very good luck," said a museum volunteer to a wide-eyed girl.
And nearby, in the Hall of Biodiversity, a cautious group peaked through the leaves of a replicated forest, hoping to glimpse a stuffed monkey. One young visitor let out a quick scream when she thought she saw something, which prompted a taunt by her brother.
The idea of spending a night in the museum sparked the imaginations of kids around the country with last year's blockbuster hit "A Night at the Museum." Starring veteran comedian Ben Stiller, it tells the story of a security guard who must both guard the possessions and protect himself from the American Museum of Natural History as its treasures come alive when the lights go out at night.
The real "Night at the Museum" has already seen much success.
Programs have sold out for the rest of the year, even though no creatures have come to life at night.
But for Jack and Lylah, there was still hope that they may be so lucky as to see magic when the lights go out.
Settled in his sleeping bag next to a giant moose, Jack eyed the stuffed animal optimistically.
"When these things come to life, I hope they trample her," he said, pointing to Lylah with a smile.
For more information: The American Museum of Natural History's A Night at the Museum: Central Park West at 79th Street, 212-769-5570, www.amnh.org/kids/sleepovers ; $109 per person.