A Race Against Time: St. George Dinosaur Discovery Site Unearths Over One Thousand Fossils in Historic Salvage Effort
by Don DeBlieux
Location of St. George Dinosaur Discovery Site.
The St. George Dinosaur Discovery Site (SGDS) is a world-class dinosaur tracksite, renowned for its remarkably well-preserved Early Jurassic-age (201–174 Ma) tracks (see Survey Notes v. 34, no. 3). Discovered in 2000 beneath a sod farm on the outskirts of St. George, Utah, the site has been carefully preserved in a state-of-the-art museum. As the city has expanded, the site is no longer on the outskirts but is now encompassed by urban development.
In January of 2025, the paleontologists at the SGDS received urgent news that the City of St. George planned to build an electrical substation on land across the street from the museum. Previous work on and near the site had documented numerous fossils in multiple strata of the Early Jurassic-age Moenave Formation. With the land slated for development, they knew a rapid salvage excavation was imperative to preserve the site’s scientifically significant fossils. News of this monumental project quickly spread worldwide via newspapers, television, and online media. As long-standing collaborators with the SGDS (for over 20 years), the Utah Geological Survey offered immediate assistance. An astounding 750 individuals responded to the call for volunteers, with over 500 people ultimately dedicating their time and effort to the excavation. The Utah Geological Survey paleontology team spent a week in March 2025 working to collect fossils and help supervise the many volunteers. In addition to the many citizen volunteers, crews from universities and museums from Arkansas, California, Colorado, Idaho, Montana, Texas, and Utah joined the excavation. Many businesses and individuals also contributed thousands of dollars to help buy equipment for the project.
In May, the city revised its plans, relocating the substation to an adjacent parcel, thereby preserving the invaluable fossil-bearing rocks. Thus, after two intense months of daily excavation, the SGDS crew could finally pause for the season, allowing them to begin assessing the collected fossils. Preliminary analysis of the extraordinary discoveries from what has now been aptly dubbed the “Substation quarry” (SQ) suggest a one-of-a-kind collection of fossils.
Remarkable Finds from the Substation Quarry
Fossils were recovered from five distinct stratigraphic levels within the Whitmore Point Member of the Moenave Formation. Most fossils were concentrated in the lower fish bed (LFB) and the upper fish bed (UFB). Collectively, over 1,000 fossils have been meticulously collected and cataloged from these two prolific units at SQ.
The LFB yielded the most complete and semi-complete fish specimens, including primitive ray-finned fishes such as semionotids and palaeoniscoids, as well as the distinctive lobe-finned coelacanths. Some of these represent previously described species, but the majority likely belong to entirely new taxa. Once excavated, these fish fossils will require painstaking preparation. The sheer volume of fossils collected means there will be years of preparation to be completed by museum staff and volunteers.
The UFB alone yielded over 700 individual fossils, predominantly consisting of individual skeletal elements. Fish remains found in the UFB primarily consist of disarticulated elements including numerous teeth, fin spines, and scales from hybodont sharks. The UFB also proved to be the primary source of terrestrial vertebrate fossils. Dinosaur remains include two types of teeth from large and small carnivorous theropods. Isolated bones belonging to theropod dinosaurs were also collected from the UFB.
This illustrative mural depicts a reconstruction of the Early Jurassic ecosystem of Lake Whitmore. Megapnosaurus dinosaurs wade into the shallow waters, while below the surface, two hybodont sharks rest on the bottom as three semionotid fish swim past. To their right, two coelacanths pursue three small palaeoniscoid fish. Several crocodilomorphs are also visible at the top of the scene. Art by Brian Engh (https://livingrelicproductions.com/)
The theropod dinosaurs discovered at the SQ, and in adjacent rock units, almost certainly represent new species. The large theropods appear to be closely related to Dilophosaurus, whereas the smaller species are likely coelophysoid theropods. Additional skeletal elements, particularly from the skull, will be necessary to formally describe them as new species.
Other notable discoveries at the SQ include a new track horizon featuring the rare footprints of swimming dinosaurs. Invertebrates, their trace fossils, and plant remains were also documented. In summary, the excavation at the SQ was a resounding success, made possible by the generous contributions of time, effort, and resources from numerous individuals and organizations. The thoughtful relocation of the substation ensures this site will remain available for future excavation, transforming a potential loss into a remarkable victory for science and the community. The vast number of fossils collected will provide years of invaluable scientific investigation, greatly enriching our understanding of the Early Jurassic ecosystem of southwestern Utah.
