NEW YORK-From age five until her teenage years, Rhoda Knight Kalt had a Friday ritual - leave school at noon and spend the rest of the day among dinosaurs.

Her grandfather, Charles R. Knight, was a celebrated naturalist artist whose paintings of dinosaurs helped shape popular perceptions of how the giant prehistoric reptiles lived.

Kalt would sit next to him at New York’s American Museum of Natural History and watch as he painstakingly sketched the fossils, which he later turned into vivid recreations that appeared in frames or in books and magazines. Yet Knight had a side passion - he loved opera, befriending divas and singing for pleasure. More than 60 years after he died, his opera side is finally coming to fruition.

An original opera, which revolves around young Rhoda and her afternoons with her grandfather, premieres Saturday, with a chamber orchestra playing inside the museum in a hall that is home to the world’s first mounted sauropod dinosaur and an imposing tyrannosaurus rex.

“Rhoda and the Fossil Hunt” will be the first opera ever performed in the dinosaur exhibition of the sprawling complex on the western edge of Central Park, according to the museum.

“My grandfather loved the opera and, as a matter of fact, he had a magnificent voice,” explained the bubbly Kalt, who called the creation of the piece “very exciting.”

Kalt, who is eager to chat at length about her life (other than to disclose her age), wrote for the defunct Junior Natural History magazine aimed at young people and still regularly visits the museum.

“Really, it was my whole childhood - coming here and being with the museum,” she said as she sat on a bench beneath the dinosaurs.

Composed by John Musto, “Rhoda and the Fossil Hunt” does not attempt to create any sort of dinosaur-themed music but keeps the tone lively - and explains some of the science, fully reviewed by the museum’s paleontologists.

“John miraculously was able to make all of these dinosaur names and scientific terms sing beautifully, like it’s Italian opera,” Eric Einhorn, the librettist, said with a smile.

With children expected to make up much of the audience, the creators kept “Rhoda and the Fossil Hunt” to 20 minutes, with the story set over one adventure-packed afternoon in the museum.

“Rhoda was unfortunately a very well-behaved little kid, and well-behaved children do not an opera make,” Einhorn said.

“You need some tension, you need action,” he said. “So with Rhoda’s permission, I condensed it down into one fanciful afternoon.”

Presented by On Site Opera, a New York company that creates immersive experiences, “Rhoda and the Fossil Hunt” was co-commissioned by Chicago’s Lyric Opera and Pittsburgh Opera and will head to the two cities after closing in New York in mid-October.

The creators also expect to draw museum-goers who may not usually see opera. With access to the performance included in a museum ticket, some viewers are expected to stumble upon it.

“It won’t quite be guerilla pop-up,” Einhorn said. “But there will still be people in the room who are completely unaware.”