They look like oversized yams, potatoes on a campfire or even small footballs.
But the pair of oval-shaped fossils unveiled Thursday at the N.C. Museum of Natural Sciences date back 97 million years, eggs from a feathered dinosaur that stood tall as a rooftop.
"Picture a 15-foot-tall chicken," said Lindsay Zanno, the museum's head paleontologist.
Before a crowd of school-age fans, Zanno showed off her team's 2016 discovery: the only clutch of oviraptorosaur eggs ever found in North America. Recovered from a rugged patch of Utah desert, the eggs offer a rare chance at understanding the reproductive life of reptiles dating to the Cretaceous period.
More than an egg, a dinosaur nest helps explain prehistoric behavior: whether eggs were buried, for example, or exposed to open air, Zanno said.
"There could be dinosaur bones in there," she said, "or something we're not expecting."
Oviraptorosaurs sported feathers, beaks and parrot-shaped heads and walked on two legs, so birdlike in their appearance that some scientists call them true birds. They typically weighed a few dozen kilograms — roughly 50 pounds — and grew a few meters long, though larger species could weigh more than a ton. The creature that laid the clutch of eggs now at Raleigh's museum represents a new species, one of several discovered in Utah that are yet unnamed.
The most complete specimens come from China, and records in North America are sparse by comparison. Zanno, whose wanderings as a paleontologist have led from Tanzania to Montana, described her 2016 Utah find as a discovery with world-class potential. Nesting sites rarely come complete with eggs, and this one is expected to produce fresh insight on the biology of birdlike dinosaurs.
Zanno's team had spent six years hiking over a portion of Utah that once stood at the edge of the Western Interior Seaway, a vast inland waterway that stretched from Alaska to the Gulf of Mexico. Though desert today, in Cretaceous times it would have supported a variety of reptiles.
Near the end of a day when temperatures flirted with 120 degrees, Terry Gates decided to inspect the knob of a hill that caught his eye. Gates, a lecturer at N.C. State University and postdoctoral scholar with the museum, found pieces of eggshell poking out that suggested whole, perfect eggs inside.
The problem soon arose of how to retrieve eggs sandwiched between two 1,000-foot mountains in the Utah wilderness. So the team returned with a helicopter in October, chiseled the "clutch" out of the hillside and carried them through the air encased in a plaster shell.
The original two that Gates spied had been freed from much of the surrounding rock, but as many as 10 likely remain inside the cluster. Over the next year, they will be visible in the museum's glass-walled laboratory, where visitors can see further study.
That casing hadn't been cut away until Saturday, making the children in the front row of the museum's unveiling some of the first eyes to glimpse the pair of eggs — Raleigh's prehistoric guests.
Josh Shaffer: 919-829-4818, @08joshshaffer