“Dinosaur Mummy” Edmontosaurus Reveals Scaly Skin, Fleshy Crest, and Perfect Hooves Thanks to Clay Preservation

In a Science paper published May 2026, paleontologists have described the most complete “dinosaur mummy” ever found: an exceptionally preserved Edmontosaurus annectens from Wyoming’s Lance Formation (~66 million years old). Nicknamed “Dakota II,” the specimen was entombed in fine-grained bentonitic clay that acted like natural plaster, replicating skin, soft-tissue structures, and even keratinous hooves in three dimensions.

The 9-meter-long hadrosaur shows тιԍнтly packed, polygonal scales across the torso and limbs—identical in pattern to modern reptiles—plus a previously unknown fleshy crest rising above the skull, likely used for display or species recognition. Most strikingly, the feet retain complete, hoof-like unguals sheathed in keratin, proving hadrosaurs walked on broad, padded hooves rather than simple claws.

“This is the first time we’ve seen a hadrosaur’s true external anatomy in life position,” said lead author Phil Manning (University of Manchester). “The clay preserved every scale, every wrinkle, and the exact shape of the crest and hooves—features that usually decay within days.”

The discovery confirms Edmontosaurus as a large, herd-living herbivore with sophisticated integument and foot morphology suited to soft floodplain terrain. It also demonstrates that exceptional preservation can occur in ordinary clay-rich environments, not just rare Lagerstätten.

After decades of skin impressions and bone-only skeletons, Dakota II has delivered the first true “living” view of a duck-billed giant—scaly, crested, and hoofed—proving that even the most common dinosaurs hid remarkable biological secrets until the right burial conditions revealed them.