Experts call it “the best impression of a 215-million-year-old dinosaur footprint” found in a decade. But her discoverer is only 4 years old.

The four-year-old girl found the dinosaur footprint on a Welsh beach that dates back 220 million years. The footprint was most likely left by a small, thin dinosaur that walked on its two hind legs.

A pristine footprint

The print is just over 10 cm long. Experts believe that the footprint was likely left by a dinosaur that was about 75 centimeters tall and 2.5 meters long and walked on its two hind legs.

Lily Wilder made the discovery on January 23 while walking along a beach in South Wales with her father and their dog. The family was on their way to the supermarket when Wilder saw the imprint on a rock.

Shortly after posting a photo of the discovery on social media, the National Museum of Wales contacted the Wilder family, and officials eventually recovered the print and took it to the museum.