For more than 150 million years, science didn’t notice a small, fast-moving dinosaur that lived in the floodplains of Jurassic North America. It lived in the shadow of giants like Stegosaurus and Allosaurus. Palaeontologists are now having to rethink what they thought they knew about how dinosaurs evolved because of a new species called Enigmacursor mollyborthwickae. This dog-sized herbivore was found in Colorado and is now on display at London’s Natural History Museum. It’s more than just a fossil; it’s a key to unlocking forgotten parts of prehistoric life.
A Century-Old Taxonomic Mystery Unraveled
The story of Enigmacursor starts with someone getting the wrong idea about who they are. The Morrison Formation, which runs across the western U.S. and is full of fossils, was found between 2021 and 2022. The fossil was first called Nanosaurus, which is a dinosaur that was named in the 1870s but isn’t well understood. But when scientists at the Natural History Museum looked at the fossils, they realised they were looking at something completely different.
Professor Paul Barrett, a co-lead author of the study, explains, “Nanosaurus was initially described from unclear bone impressions found in hardened sand, which wouldn’t even be sufficient to define a species today.” Scientists were able to confirm that Nanosaurus wasn’t actually a distinct group of animals, thanks to the well-preserved skeleton of Enigmacursor.
The Life and Times of a Jurassic Sprinter
Enigmacursor was made to be fast. It was only 0.5 metres (1.6 feet) tall and 1 metre (3.3 feet) long. Its long back legs and “incredibly large feet” make it look like it could run fast. It probably ran between the legs of big sauropods to get away from predators like Ceratosaurus.
This dinosaur wasn’t just fast; it was also young. The specimen had unfused vertebrae, which means it was a young dinosaur, maybe even a teenager by dinosaur standards. Professor Susannah Maidment, who co-wrote the study with Professor Maidment, says, “It might not have grown much bigger.” Even though it’s still young, the anatomy of Enigmacursor shows that it is perfectly suited to its dangerous world.
Why Small Dinosaurs Have Been Overlooked
The Morrison Formation is known for its huge dinosaurs, but Enigmacursor shows that palaeontology is very biassed: it often ignores small species. Maidment says that “fossil hunters tend to focus on big, impressive skeletons.” It’s easy to miss smaller bones or, even worse, think they’re not important.
We don’t know as much about Jurassic ecosystems because of this mistake. Enigmacursor’s discovery makes it seem like there are a lot more small dinosaurs hiding in museum drawers or still buried in the ground, waiting to change history.
A Surprising Link to China
What was one of the biggest surprises? Yandusaurus hongheensis, a 3-meter-long herbivore from China, is the closest known related of Enigmacursor. It is not from North America. This link suggests that small ornithischian dinosaurs were more common in the ancient world than we thought. It makes us wonder how these animals moved about and changed throughout time.
Barrett says, “This discovery changes the way we think about how dinosaurs spread out.” “We might be looking at a Jurassic world that is much more connected than we thought.”
The Legacy of Molly Borthwick
Mollyborthwickae is named after Molly Borthwick, the donor whose generosity made it possible for the Natural History Museum to get the fossil. If she hadn’t helped, this “mysterious runner” might have stayed in private hands, and its scientific value would have gone unnoticed.
The museum hasn’t said how much the fossil costs, but it is priceless to science. Barrett says, “Making such a specimen available to the public is important for inspiring future generations of palaeontologists.”
What’s Next for Jurassic Paleontology?
This is just the first step with Enigmacursor. Researchers think that there are other small dinosaurs in the Morrison Formation that have been wrongly identified or not found yet. Some of these may already be in museum collections, but they are either mislabelled or not noticed.
“Taxonomy isn’t glamorous,” Maidment says, “but it’s the basis for everything we do.” “If we make a mistake, everything we know about evolution will be wrong.” The Jurassic period may soon give up even more of its secrets now that scientists are looking more closely at these small dinosaurs.
Conclusion: A Reminder That Discovery Never Ends
Enigmacursor proves that some of the most thrilling discoveries still come from the earth beneath us, despite the fact that satellite images can map every corner of the planet. Barrett is spot on when he says, “When you’re looking for giant dinosaurs, sometimes the real surprises are right at your toes.”
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Suhail Ahmed is a passionate digital professional and nature enthusiast with over 8 years of experience in content strategy, SEO, web development, and digital operations. Alongside his freelance journey, Suhail actively contributes to nature and wildlife platforms like Discover Wildlife, where he channels his curiosity for the planet into engaging, educational storytelling.
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