Dog-sized dinosaur that scuttled between feet of giants 150m years ago discovered

Palaeontologists say they hope the discovery could open the way for hundreds more identifications

A new, dog-sized species of dinosaur that once scuttled between the feet of giants has been discovered after being wrongly categorised.

Enigmacursor, which means “mysterious runner”, is believed to have lived around 150 million years ago.

At 64 cm tall and 180 cm long, the dinosaur is roughly the size of a Labrador but with larger feet and a tail that was likely longer than the rest of the dinosaur.

Its long legs would have enabled this little herbivore to dart away from danger as it navigated the network of rivers and floodplains stretching across large parts of the western United States, where it was discovered.

It likely existed alongside the giants of the dinosaur species, including the diplodocus and the carnivorous Ceratosaurus.

Experts say the Enigmacursor was the size of a Labrador but likely with much larger feet (EPA)

On Thursday, it will become the first new dinosaur to go on display at the Natural History Museum. It will be placed on the balcony of the museum’s Earth Hall.

The fossils were found on private land between 2021 and 2022 and put up for sale through a commercial fossil dealer.

The finding was originally advertised as an animal from the Nanosaurus, a species of which little is known, which was first named in the 1870s.

After the Natural History Museum purchased the fossils, palaeontologists realised that their understanding of the Nanosaurus species was based largely on the preserved impressions of bones pressed into hardened sand.

But this discovery included an almost full skeleton. Experts even believe they were able to estimate the age of the dinosaur based on the lack of neural arches fused in place along the dinosaur’s spine, suggesting it was a teenager that died before it was fully grown.

The dinosaur will go on display at the Natural History Museum on Thursday (EPA)

Experts say the discovery offers hope that the hundreds of unidentified bones, previously classified as Nanosaurus, can now be properly understood.

Professor Susannah Maidment, one of the lead researchers into Enigmacursor, says she hopes this will open the way for the identification of many more smaller dinosaurs that often get ignored.

“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,” she said. “Smaller dinosaurs are often left behind, meaning there are probably many still in the ground.”

“Enigmacursor shows that there’s still plenty to discover in even this well-studied region, and highlights just how important it is not to take historic assumptions about dinosaurs at face value.”