Utah State Dinosaur: Utahraptor ostrommaysorum

When James Kirkland, Robert Gaston, and Donald Burge published the formal description of Utahraptor ostrommaysorum in 1993, they were describing a dromaeosaurid roughly twice the size of Deinonychus and six to eight times the mass of Velociraptor. Kirkland has noted that the film's Velociraptors — scaled up from their actual modest size for dramatic effect — ended up accidentally predicting Utahraptor. The public's new appetite for large raptors, fed by the film, was met almost simultaneously by the announcement of an actual large raptor.

The film generated public interest in raptor biology at exactly the moment Utahraptor needed that attention. Utahraptor became famous almost instantly — and some of that fame was borrowed from a fictional version of a different, smaller animal. The public largely didn't distinguish between the movie's scaled-up Velociraptors and the newly announced real animal. The distinction mattered to scientists; it didn't matter to the audience.

The discovery site itself — in the Cedar Mountain Formation of Grand County, near what is now the Dalton Wells Quarry area outside Moab — is about as far from Hollywood as it's possible to get in the continental United States. The fossil was found in actual Utah desert, not on a movie set.

The species name ostrommaysorum honors two people. John Ostrom was a Yale paleontologist whose 1970s work on Deinonychus and the bird-dinosaur connection fundamentally changed how scientists think about theropod physiology and behavior. His research argued that birds are living dinosaurs — an argument that is now accepted consensus, but was genuinely controversial when Ostrom first pushed it. Naming Utahraptor partly after Ostrom was a recognition of how his work had set the stage for understanding animals like the raptors.

The second honoree is Chris Mays, founder of Dinamation International Society, which provided funding for the research that led to the Utahraptor description. The dual honor is encoded in the plural possessive: ostrommaysorum is the Latin possessive plural of Ostrom and Mays combined.

One more nomenclatural detail: the species was originally published as U. ostrommaysi, with a single Latin possessive. It was corrected to ostrommaysorum — the proper plural possessive for two honorees — in a 2013 paper. This is a grammatical emendation, not a reclassification. The species is the same animal; only the suffix changed to follow the rules of Latin zoological nomenclature correctly.

In 2001, paleontologist Scott Madsen discovered an extraordinary block of Cedar Mountain Formation sandstone in Grand County, Utah, containing the bones of multiple Utahraptor individuals at different growth stages — from juveniles to large adults — along with the skeleton of a large iguanodontian dinosaur in apparent association. The block was interpreted as a 'death trap': possibly a mud pit or quicksand feature that trapped the iguanodontian first, and then attracted multiple Utahraptors that became mired while attempting to feed.

The block weighed approximately 9 metric tons. Extracting it, transporting it, and preparing its contents became a multi-year, partially crowdfunded research project led by James Kirkland and the Utah Geological Survey. The preparation process alone took years in the lab, requiring careful removal of the surrounding matrix from bones that were often still articulated. The project generated significant public interest and was partially supported by a public crowdfunding campaign.

The Utahraptor Project block has the potential to redefine what is known about Utahraptor biology, growth rates, and behavior in ways that single-specimen finds cannot. A growth series from juveniles to adults in one deposit — if confirmed by continued preparation — would provide data on ontogenetic changes that are otherwise unavailable for the species. As of 2024, the preparation and analysis are ongoing.