Dog-Sized Neornithischian Dinosaur Unearthed in Colorado

A new remarkable genre and species of neornithischian dinosaur named Enigmacursor Mollyborthwickae was identified from a postcranial skeleton preserved in three dimensions found in the Morrison formation of Colorado, in the United States.

Reconstruction of the life of Enigmacursor Mollyborthwickae. Image credit: Bob Nicholls.

Enigmacursor Mollyborthwickae Completed our planet during the end of the Jurassic era, between 150 and 145 million years.

This dinosaur was a two -legged herbivore of about 0.5 m (1.6 feet) high and a little more than 1 m (3.3 feet) long.

The species should have browsed the flood plains of the western United States in the shadow of giants as Diplodocus And Stegosaurus.

“There are signs that the dinosaur was not entirely cultivated: the upper section of the vertebrae (neural arches), which are formed separately in the lower parts and merge like the age of the animal, were not completely fused in place, suggesting Enigmacursor Mollyborthwickae Perhaps quite young, ”said the Natural History Museum, the paleontologists of London Susannah Maidment and Paul Barrett.

Enigmacursor MollyborthwickaeThe partial skeleton but in three dimensions with a few associated teeth was determined in 2021 and 2022 of a commercial career of the Morrison training in the county of Moffat, Colorado

At the time, the specimen was considered a NanosaurusA little -known species of a small herbivorous dinosaur named for the first time in the 1870s.

However, looking at it, paleontologists judged the original Nanosaurus Specimen too badly preserved to serve as a reliable reference to identification.

The best quality fossils having been found, they officially set aside the name Nanosaurus In the interest of taxonomic stability.

The differences between the original sample and the new specimen were the latest parts of the puzzle to confirm it as a new genus and species.

“The discovery of Enigmacursor Mollyborthwickae Improves the diversity of ornithischian dinosaurs from Morrison’s formation and provides new information on their anatomy, “said the researchers.

“In addition, this shows that there is an additional cryptic diversity of ornithischians of the formation of Morrison with a full -bodied, suggesting that they were a more diverse component of these late jurassic ecosystems than what was done previously.”

An article describing Enigmacursor Mollyborthwickae was published this week in the journal Royal Society of Open Sciences.

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Susannah Cr Maidment & Paul M. Barrett. 2025. Enigmacursor MollyborthwickaeA neornithischian dinosaur of the higher education of Morrison Jurassique in the West of the United States. R. Soc. Dynamism 12 (6): 242195; DOI: 10.1098 / RSOS.242195