The following story is contributed by the Natural History Museum of Los Angeles County, one of Natural History magazine’s Museum Partners. Members of any of our partner organizations receive Natural History as a benefit of their museum membership.

The Natural History Museum of Los Angeles County, which opened its doors to the public in 1913, is the largest natural and historical museum in the western United States, safeguarding more than 33 million diverse specimens and artifacts. Its main exhibition halls, located at 900 Exposition Boulevard, feature grand dioramas of African and American mammals, rare dinosaurs and fossils, marine animals, Pre-Columbian culture, gems and minerals, and historical artifacts from California and Southwest history, as well as early Hollywood memorabilia. The Museum is also an active research center, spanning living and fossil invertebrates, vertebrates, mineralogy, anthropology, and history. The Natural History Museum also includes the William S. Hart Ranch and Museum, once the home of that silent film actor, and the Page Museum at the La Brea Tar Pits.

Dr. Luis Chiappe wants nothing less than to transform the Natural History Museum into the West Coast hub for dinosaurs. A crucial component of this mission is an ambitious fieldwork program.

“With expeditions,” Chiappe says, “we create excitement within the city about dinosaurs, awakening this romantic idea of dinosaur excavations in the middle of nowhere, and bringing fossil treasures back to the Museum.”

The fossil that the expeditions yield fuel scholarship, education programs and behind the scenes “laboratory” exhibits that explore the scientific processes of paleontology. They will also help stock the new dinosaur hall, scheduled to open in the summer of 2011.

Over the last decade, Chiappe and his staff, who formed the in-house Dinosaur Institute in 2005, have prospected, excavated and studied dinosaurs in remote parts of South America, Kazakhstan, China, and Mongolia, and the badlands of the American West—Arizona, California, Montana and Utah. It was the latter that hosted the action this April, when the DI team spent several weeks in southeastern Utah. It was its third fieldwork season in the area.

Destination Utah

Between the small towns of Bluff and Blanding, the team camps on federal land managed by the Bureau of Land Management. Here, unfolding between Navajo reservations, the cave dwellings of Mesa Verde National Park and the Four Corners Monument, is a sequence of Late Jurassic rock called the Morrison Formation. It’s the richest treasure trove for dinosaurs in the western United States.

Dr. Lowell Dingus, a writer, geologist and research associate at the American Museum, was in the field with the team, and describes the formation. It contains sediments deposited on a 150-million-year-old floodplain, and the sandstone layers represent sand bars that migrated down the river bed in currents. The bones in some of the team’s quarries are probably jumbled up because they were moved around a bit by those currents.

“The finer-grained layers of mudstone and siltstone represent flood deposits laid down when the river over-topped its banks and flooded the lowlands adjacent to the river course,” Lowell says. “At that time, the headwaters of those rivers were located in a mountain range that essentially constituted a precursor of the modern Rockies.”

Seasons Past

During the first Utah outing in 2007, the Dinosaur Institute group mostly prospected. Hikers armed with rock hammers and GPS devices canvassed hills layered with orange sandstone, popcorn mudstone (no wordplay here: it looks like popcorn in mud), and surprising washes of bright blues, greens and reds. Resting amid the boulders of the ancient floodplain, they found what looked to be a sauropod—a long-necked dinosaur that lived 150 million years ago.

When they came back in June 2008, they set about excavating that creature. As the matrix (dirt and rock surrounding the fossil) was cleared away, a beautiful specimen was revealed, but the dig was challenging. Excavators were terrorized by biting gnats, the only benefit of which was inspiration for the specimen’s nickname Gnatalie.

On the same trip, they also collected 15–20 footprints made by sauropods and theropods; an enormous brachiosaur humerus; and the first record of a stegosaur track in the area.

A few feet from the Gnatalie quarry, they poked around another promising site, another sauropod they thought—with the same green-colored bones. But the trip was over, so they covered up their find with plaster caps, and shoveled dirt on top to protect it from two elements—the weather, and the poachers known to dig up sites once the excavators leave, and sell the bones they find.