New dinosaur fossils were discovered at the Dinosaur National Monument, leading to the first excavation there in more than 100 years, officials revealed Friday.

The National Park Service said that parking lot construction was underway in September near the Quarry Exhibit Hall in the Utah side of the park when the dinosaur fossils were uncovered. Dinosaur National Monument is located on the border between Colorado and Utah, about 300 miles west of Denver.       

A portion of dinosaur-bearing sandstone was exposed when asphalt was removed on Sept. 16 by workers. Construction was immediately paused to allow paleontologists to assess and excavate the fossils.

“The fossils belong to a large, long-necked dinosaur, most like Diplodocus, which is common in this bonebed,” the NPS said in a statement.

Approximately 3,000 pounds of fossils and rock were removed during the excavation between mid-September and mid-October, the NPS said. The fossils are being cleaned and studied at the Utah Field House of Natural History State Park Museum in Vernal, Utah.

According to NPS, the bonebed area had not been excavated for fossils since the original excavations at the site ended in 1924. Meanwhile, the parking lot and road improvement construction project was completed once the excavation was done.

Research released last October suggests that dinosaur populations were still thriving in North America before an asteroid smacked the Earth 66 million years ago.

In January 2025, a nearly 70-million-year-old dinosaur fossil was discovered during a parking lot project at the Denver Museum of Nature and Science. It is the oldest dinosaur fossil ever found within Denver’s city limits.

“This fossil comes from an era just before the mass extinction that wiped out the dinosaurs, and it offers a rare window into the ecosystem that once existed right beneath modern-day Denver,” the museum’s Curator of Geology, James Hagadorn, said at the time.