The ‘triceratops' unearthed in Thornton isn't actually a triceratops, after all

THORNTON, Colo. – It’s a case of prehistoric mistaken identity: The dinosaur unearthed by a construction crew in Thornton earlier this year isn’t actually a triceratops as initially thought.

Construction workers uncovered the fossilized bones on Aug. 28 while working on Thornton’s new city building. Scientists initially identified the skeleton – which they said was the most complete Cretaceous-period fossil ever unearthed in the state – was that of a triceratops.

The skeleton was transferred to the Denver Museum of Nature and Science, where staff and volunteers have been carefully cleaning and examining the bones. Close examination of the skull’s frill, or “shield” – the section of bone that projects backward from the skull – shows it actually belongs to a torosaurus, a close relative of the triceratops.

Museum staff say that torosaurus and triceratops are difficult to distinguish, but the torosaurus has a longer, thinner frill with two large holes. Those features only became apparent once the skull had been cleaned and compared to triceratops skulls.

PHOTOS: Rare torosaurus fossil found in Thornton at construction site

Staff at the Denver Museum of Nature and Science say the torosaurus is much more rare than the well-known triceratops.

“Not only is the fossil more complete and better preserved than I imagined, but it has also revealed itself to be something extremely rare,” said Joe Sertich, the museum’s curator of dinosaurs. “While the number of good Triceratops specimens collected from the American West likely exceeds 2,000 individuals, there are only about seven partial skulls of Torosaurus known. The Thornton beast is by far the most complete, and best preserved, ever found.”

Museum staff say cleaning will continue for several months. Visitors can watch the process unfold at the Fossil Prep Lab.

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