For the first time in over a century, fossil excavations took place at Dinosaur National Monument on the border of Colorado and Utah, where bones were discovered during parking lot construction near the park’s famed Quarry Exhibit Hall.
The fossils likely belong to a long-necked, herbivorous sauropod called Diplodocus longus, which lived during the Late Jurassic period, approximately 150 million years ago. Several Late Jurassic sauropods, common in the bonebed, were already on display at the monument.
Staff at the monument anticipated that construction crews removing an old parking lot east of the Quarry may encounter remains because the lot was built on top of rock and soil fragments discarded during the original excavations, which ended in 1924.
On Sept. 16, 2025, the parking lot project was paused after staff monitors identified fossils in an exposed sandstone wall. Over the next two months, park staff worked with volunteers, construction crews and a Utah Conservation Corps team to excavate 3,000 pounds of fossils and rock.
Further excavations will take place in the spring in order to avoid winter weather as crews work to extract the remaining parts of the skeleton, which extends into the area surrounding the parking lot. Only about 20 feet of the sauropod has been recovered, and the animals were usually about 80 feet long.
The National Park Service announced the discovery on Jan. 16, directing curious visitors to the nearby fossil preparation lab at the Utah Field House of Natural History State Park Museum. Some of the newly discovered fossils are also currently on display at the Quarry Exhibit Hall, also known as the “Wall of Bones.” The attraction currently boasts an impressive 1,500 dinosaur fossils encased in rock.
The new Diplodocus isn’t the only dinosaur to have been recently discovered in the region. In 2024, the Denver Museum of Nature and Science announced that while drilling in the parking lot for a geothermal energy project, crewmembers discovered the vertebra of a 67.5 million-year-old herbivorous dinosaur 763 feet underground.
The fossil, which museum staff believe may belong to either Thescelosaurus or Edmontosaurus, is the deepest and oldest dinosaur fossil ever found in Denver city limits.
