Did this overlooked dinosaur spend its final days digging underground to survive?

Nature · Published 3 October 2026 Swipe more like this →

In short: Thescelosaurus neglectus, a late-surviving dinosaur from the Cretaceous, has long baffled paleontologists with its robust, enigmatic anatomy. New 3D digital reconstructions of its braincase reveal surprising neurological specializations, suggesting this creature may have possessed a hidden talent for burrowing, a behavior rarely identified in the broader ornithischian dinosaur family.

For over a century, Thescelosaurus neglectus remained a puzzle. First described by Charles W. Gilmore in 1913, the genus name translates to 'marvelous lizard,' while its species name, neglectus, reflects the fact that its type specimen sat forgotten in a packing box for years. Despite its status as one of the last non-avian dinosaurs before the mass extinction 66 million years ago, its exact lifestyle—whether agile runner or slow-moving grazer—has been heavily debated. Recent CT-scanning of the specimen NCSM 15728, nicknamed 'Willo,' has finally provided a clearer look at its internal biology by allowing researchers to reconstruct its brain and inner ear.

The digital endocast reveals that Thescelosaurus possessed a relatively small brain, comparable in cognitive capacity to modern reptiles. However, the sensory anatomy tells a more specialized story. Thescelosaurus exhibited unusually well-developed olfactory lobes and anterior semicircular canals, which are linked to acute senses of smell and vestibular sensitivity. Conversely, its hearing range was narrow, with a limited ability to distinguish high frequencies. This specific combination of traits—heightened smell and balance paired with poor hearing—is a hallmark of modern burrowing animals. While earlier-diverging thescelosaurids show skeletal evidence of subterranean habits, this study provides the first neurological evidence for such behavior within the Ornithischia clade.

Whether these adaptations were a direct ecological response or an inherited trait remains a subject of scientific inquiry. Thescelosaurus was a robust, large-bodied animal, and its postcranial anatomy has previously led to conflicting theories about its movement, ranging from cursorial agility to graviportal stability. By illuminating the sensorineural patterns of this under-sampled dinosaur, researchers are expanding our understanding of the ecological diversity present in the final days of the Cretaceous. This discovery highlights that even well-known fossils can harbor secrets, proving that the last survivors of the dinosaur age were far more complex and behaviorally diverse than previously assumed.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• The first complete dinosaur skeleton ever found remained a mystery for 160 years
• Did this duck-billed dinosaur use its elaborate head crest as a natural trombone?
• The chambered lizard: how a common dinosaur shaped our view of the giants
• Why a century-old taxonomic tangle finally revealed a new dinosaur species
• The hatchet-headed dinosaur whose identity was hidden in plain sight for decades
• The three-spined stickleback is a tiny fish that reveals how evolution happens in real-time.
• The scythe lizard: a giant theropod that traded meat for a plant-based diet
• A 250-million-year-old fossil reveals an unlikely Triassic friendship in a burrow
• The ancestors of all mammals were once the dominant land animals on Earth.
• Australia's legendary marsupial lion was a predator with a bizarre, herbivorous family tree
• These ancient jawless fish possessed stomachs long before jaws ever evolved in vertebrates
• The saber-toothed predator that was not a cat, but a marsupial relative

More in Vertebrates · More in Nature · Latest · A–Z · All topics