More than 66 million years ago, a fascinating duck-billed dinosaur called Edmontosaurus annectens left behind something remarkable. Researchers from the University of Chicago found a preserved clay mask in its fossils in Wyoming. This unique discovery gives us a new view of dinosaur “mummies.”
What Are Duck-Billed Dinosaurs?
Duck-billed dinosaurs, or hadrosaurs, were common plant-eaters during the Late Cretaceous period, around 75 to 65 million years ago. They had wide, flat snouts similar to modern ducks. This shape helped them munch on leaves and shrubs. Inside their mouths were hundreds of teeth that worked like a grinding machine, ideal for breaking down tough plant material. Their efficient teeth made them some of the most advanced herbivores of their time.
The Clay Preservation Process
Unlike most fossils found in oxygen-poor areas, Edmontosaurus annectens was buried in sandy river channels. After it died, its body dried in the sun, only to be swept away by a sudden flood. As it decayed, microbes formed a thin layer that attracted clay minerals from the surrounding sediment. This created a detailed template that captured the dinosaur’s texture before its flesh disappeared.
Professor Paul Sereno notes, “It’s a complete view of a large dinosaur that we can really trust. The Wyoming badlands are a unique ‘mummy zone’ that hold many surprises.”
Reconstructing the Dinosaur’s Body
Using advanced imaging, scientists pieced together the Edmontosaurus‘s body in stunning detail. The dinosaur had a fleshy crest along its neck and back, and its intricate skin displayed polygonal scales. This suggests it had a flexible hide rather than thick armor, supporting the clay templating theory.
“The two specimens complemented each other beautifully,” Sereno said. “For the first time, we could see the whole profile rather than scattered patches.”
Astonishing Discoveries About Its Feet
A notable finding was beneath Edmontosaurus’s feet. CT scans showed wedge-shaped hooves that wrapped around its toes. This makes Edmontosaurus the earliest known hooved reptile and the first land vertebrate with different foot postures between its front and back legs. The front limbs had hooves while the hind limbs featured both hooves and fleshy pads, allowing for a mix of walking and running.
Sereno emphasized, “There are so many amazing ‘firsts’ in these duck-billed mummies. It changes how we understand the evolution of dinosaurs.”
A Rare Natural Mummification
Researchers outlined a four-step process of natural mummification. First, the dinosaur dried out under sunny conditions. Then, a flood buried its body, filling cavities with sediment while forming a biofilm on the surface. Finally, clay minerals stuck to the biofilm, creating a protective mask before the tissues faded away.
This process, called terrestrial clay-templated preservation, is rare, especially in river environments. Therefore, this discovery is one of paleontology’s most significant finds.
The Wyoming “Mummy Zone”
The Wyoming “mummy zone,” less than ten kilometers wide, continues to surprise researchers with well-preserved fossils, including Edmontosaurus, Triceratops, and even Tyrannosaurus rex. The unique geological conditions in this area allowed for repeated instances of clay preservation.
“This may be the best paper I’ve released,” Sereno said. “It tells a coherent story about how these remarkable fossils were created.”
Conclusion
This newfound understanding of Edmontosaurus shows us not just how these creatures looked but also the delicate processes that preserved their last moments in clay. The study published in the journal Science highlights a breakthrough in how scientists interpret ancient fossils, opening new doors to our understanding of dinosaurs.
Now, thanks to modern research, we have an exciting glimpse into the world of these magnificent creatures that once roamed the Earth.
