J. Lee Howard and Derek Anderson take a walk down memory lane as they snake their way through Dinosaurs in Their Time, reminiscing about the Dinosaur Hall of their youth and that famous—and pretty terrifying to their former grade-school selves—mural of T. rex. They’ve come to the Museum of Natural History on a chilly Friday evening for a date night with their wives. “Who doesn’t want to be in a museum at night?” Howard exclaims.

Photos: Joshua Franzos

Oddities… After Dark is the museum’s second event in a new series combining happy hour—complete with a cash bar and music—with a natural-history-themed program just for adults. For $10 ($15 at the door), the 21+ crowd gets the run of the museum for four hours and one-night-only special access to some of the museum’s hidden treasures and world-famous experts, in addition to guest experts on everything from the paranormal to collecting all things bizarre.

This past October’s “haunted museum” theme featured ghost stories, paranormal specialists, and meet-and-greets with the museum’s live creepy crawlies. On this occasion, “oddities” pairs a special showing of Silence of the Lambs (including scenes filmed in the museum’s very own bug rooms) with specimens from the museum’s collection of large moths with a creepy name: Death’s Head Hawkmoths. Known for their skull-like markings, this moth species was made famous by the hit film. Researcher Stan Gordon, a Greensburg native, is also on hand to share his 55 years of experience investigating UFO and Bigfoot sightings. While he says he’s never seen anything paranormal himself, in 1969 he set up a public hotline, and has talked to many people who say they have.

“In the past, we’ve offered lectures and more formal events for adults,” says Chelsey Pucka, assistant director of visitor experience at the museum. “We wanted to do something different—something that would bring adults out with their friends and spouses for a fun adventure.”

The plan worked. The first three After Dark events sold out, accommodating more than a thousand people each night. Museum-goers say part of the appeal is the simple act of walking around the museum with other adults. On this particular evening, it’s a diverse mash-up: college students, middle-aged couples on dates, groups of friends still in their work attire, even grandparents enjoying a night out with their grown grandchildren.

A trio of students from Carnegie Mellon University wearing near-matching skinny jeans and striped t-shirts are visiting the museum for the first time. “This is a good reason to come, it’s something different to do,” says Will St. Martin, the instigator of the group. He lifts his tall can of Pabst Blue Ribbon ever-so-slightly. “Being able to walk around with a beer helps.”

It’s a fact not lost on Howard and Anderson, who enjoy a beer while they peer—way up—at the dinosaurs. In nearby Bonehunters Quarry, an interactive fossil dig swarming with children on a typical museum day, four women balance on varying heights of high-heeled shoes as they squat, chisels in hand, to scrape away the sand-wax mixture that covers the realistic fossil casts in the replica of Dinosaur National Monument in Utah.

Real-life dinosaur digs and other scientific expeditions are one way the museum adds to its collections. Another is when individuals call and say they have something valuable or unusual to donate. The latter was the case for the evening’s audience-favorite, a two-headed calf that quickly became the star of more than one visitor selfie. The calf escaped obscurity twice—once by the farmer who donated the animal after its death, and then again when the museum scrapped plans to deaccession it in the mid-20th century.

“Now it’s been here another 50 years,” says museum educator Bonnie Weiss, who loves this real-life oddity “because it’s authentic; it was born that way,” unlike the shrunken monkey head [another oddity on display] that was “made for a sideshow to deceive.” An older woman in the crowd surrounding Weiss affirms that she saw a similar calf as a child, and she and Weiss confer over the wonder, and weirdness, of nature.

“As a staff, we’re constantly showing each other odd, obscure, or just really cool things we discover in the collections,” says program manager Mallory Vopal, noting that less than 1 percent of the museum’s holdings are on display, and that the museum’s scientific staff enthusiastically step forward to identify treasures for the themed events. “We wanted to share some of that with our visitors.”

Other peculiarities on display: jars housing a preserved five-legged frog and a monitor lizard with two penises. Weiss asks her many onlookers, “Is it weird that they have two penises or that we put them in jars?,” she jokes. “I think we’re stranger.”

None, perhaps, as strange as “Mr. Arm,” owner of Swissvale’s Trundle Manor, a steampunk mishmash of antique taxidermy, jarred specimens, vintage medical equipment, and traveling creep show. On an evening celebrating the oddest of the odd, the museum invited the collector-entertainer to set up shop just outside the entrance to Dinosaurs.

Visitors gape at Mr. Arm’s cryptozoology as they listen to his wayward tales of how these creatures came to be. In a bell jar stands an “undead” rat fink, described as part raccoon and part turkey, wearing none other than red pants.

“There are more things in this world than the beauty that nature has provided,” says Arm, who crafts the mixed-creature taxidermies and the mythologies behind them. “My [specimens] are much better,” he quips. “Horrible, but better.”

He turns visitors’ attention to a family of concocted turtle-ducks displayed on the table in front of him. It turns out that a lonely stuffed turtle in Arm’s care received a mail-order duckling bride from China. Arm says, “They fell madly in love as I drilled a hole in the turtle and shoved them together, because that’s how true love is born.”

For Pucka and Vopal, the weirdness and the fun were just what they were hoping the night would bring. “People were laughing in our halls,” Vopal says. “People were dancing in our halls. For a natural history museum, that’s radical.”