Science

Meet the Enigmatic 'Runner' Dinosaur: A Jurassic Game Changer from Colorado!

2025-06-26

Author: Wei

A New Discovery from the Jurassic Era

A fascinating 'runner' dinosaur, approximately the size of a dog, roamed the ancient floodplains of what is now Colorado around 150 million years ago. This newly identified species, dubbed Enigmacursor mollyborthwickae, is reshaping our understanding of Jurassic-era dinosaurs.

Small but Mighty: The Impact of E. mollyborthwickae

Despite its modest dimensions—about 3 feet long and 1.5 feet tall—this two-legged herbivore is making significant waves in the scientific community. Unearthed by a private fossil company between 2021 and 2022, the specimen was initially misidentified as Nanosaurus, another small dinosaur from the famed Morrison Formation. However, when the Natural History Museum in London acquired the skeleton, researchers discovered it was anything but Nanosaurus, questioning the validity of many classifications tied to this iconic rock formation.

The Morrison Formation: A Treasure Trove of Dinosaurs

The Morrison Formation is celebrated for its rich array of dinosaur fossils, including the spiky Stegosaurus and the fearsome Allosaurus, which coexisted with E. mollyborthwickae. Yet, as highlighted in a recent study published in the Royal Society Open Science, there’s still a treasure trove of smaller dinosaurs waiting to be uncovered.

Retracing the Past: Scientific Curiosity Rekindled

According to Susannah Maidment, study co-lead author and senior researcher at the Natural History Museum, the focus on larger dinosaurs has overshadowed the existence of smaller species. “Smaller dinosaurs are often left behind, meaning there are probably many still in the ground,” she notes.

From Fossil to Classification: The Journey of E. mollyborthwickae

The fossil, excavated by Dinosaurs of America, LLC and later bought by London’s David Aaron art gallery before arriving at the Natural History Museum, underwent thorough examination. The initial classification of Nanosaurus was based on limited fossilized remains, mainly impressions in hardened sand, which are notoriously tricky to study.

Unraveling Mysteries Through Technology

Researchers used 3D scanning technology to generate virtual images of E. mollyborthwickae’s bones, revealing a distinct combination of leg features that set it apart from its contemporaries. Their analysis determined that this peculiar dinosaur’s closest relative is Yandusaurus hongheensis, a herbivore from China.

A New Name for a New Era

As a result of these investigations, Barrett and Maidment established a new genus for this specimen. The name Enigmacursor captures the essence of its mysterious classification, combining the Latin word 'cursor,' meaning 'runner,' with 'enigma' to highlight the ongoing questions surrounding its lineage. To honor museum donor Molly Borthwick, who contributed to the purchase of the fossil, the species was named mollyborthwickae.

The Jurassic Continues to Surprise!

With this remarkable find, it's evident that the Jurassic period still holds countless secrets waiting to be uncovered. As scientists delve deeper into the fossil record, who knows what other shocking revelations await in the sediment?