From Rocks to Roars: Dog-Sized Dinosaur Unearthed from Colorado Rock Formation

International Business Times

07-07-2025

A latest journal article, published in Royal Society Open Science, revealed that researchers have unearthed a new species of dinosaur from the famed Morrison Formation in Colorado.
According to the article, scientists have named the speedy, dog-sized dinosaur Enigmacursor mollyborthwickae. The Natural History Museum in London has its skeleton, or what fossil hunters could find of it in Moffat County, on display.
The news release from the museum stated that the scientists said the dinosaur discovered was only about 1 meter long, but there are signs that it wasn't fully grown.
The National Park Service said that the Morrison Formation of sedimentary rock from the late Jurassic period is named after the Colorado town but spans across the western United States.
Susannah Maidment, one of the lead authors of the Royal Society Open Science article and a researcher with London's Natural History Museum, said, "While the Morrison Formation has been well-known for a long time, most of the focus has been on searching for the biggest and most impressive dinosaurs," adding, "Smaller dinosaurs are often left behind, meaning there are probably many still in the ground."
Between 2021 and 2022, Enigmacursor mollyborthwickae bones were discovered on the Skull Creek Estates, a private Colorado land near Dinosaur.
According to the London Museum, Maidment and her co-author, Paul Barrett, discovered the fossils after they were sold by a commercial dealer and eventually found their way to a London art gallery.
The partial skeleton was initially identified by scientists as belonging to the plant-eating dinosaur Nanosaurus, which was found in 1877.
The press release stated that Maidment and Barrett started to investigate further and found that the Nanosaurus label was ill-defined and based more on preserved dinosaur impressions than actual bones.
Maidment stated, "Now, however, we have found hundreds of small dinosaurs from all over the world and know that the fossils of Nanosaurus just aren't that useful, let alone enough to name a species with."
"As a result, it made sense to put them to one side and name Enigmacursor as a new species instead," she added.
She concluded that there are probably a lot of tiny dinosaurs out there that are just waiting to be properly identified in museum collections or discovered underground, including Enigmacursor mollyborthwickae.