Exceptional specimens of the late Cretaceous period duck-billed dinosaur, Edmontosaurus annectens, have been meticulously studied by paleontologists. Through the application of a suite of advanced imaging technologies, researchers have successfully rendered a lifelike reconstruction of the species, depicting features such as a prominent crest adorning its neck and torso, a series of dermal spines along its tail, and hoof-like structures encasing its toes. This detailed anatomical understanding, corroborated by fossilized trackways, now provides a tangible representation of Edmontosaurus annectens.
Life reconstruction of Edmontosaurus annectens. Image credit: Dani Navarro.
“This represents the inaugural instance wherein we possess a comprehensive, fully fleshed-out portrayal of a substantial dinosaur with a high degree of confidence,” remarked Professor Paul Sereno of the University of Chicago, the principal investigator of the research initiative.
“The unique geological formations in Wyoming, where these discoveries were unearthed, constitute an extraordinary ‘mummy zone’ holding further potential for revelations from fossil material gathered over many years by teams of university undergraduates.”
By consulting historical photographic records and conducting meticulous fieldwork, Professor Sereno and his team successfully pinpointed the precise locations in east-central Wyoming where several renowned dinosaur ‘mummies’ were initially discovered in the early twentieth century, thereby delineating a concentrated ‘mummy zone.’
Within these stratified alluvial deposits, they exhumed two novel ‘mummies’ belonging to Edmontosaurus annectens – one representing a juvenile and the other an adult – both exhibiting extensive contiguous regions of preserved epidermal surface.
Leveraging these remarkably preserved specimens, the researchers were able to construct a complete, soft-tissue depiction of the species.
“The two specimens proved to be exceptionally complementary,” Professor Sereno stated.
“For the first time, we were afforded a complete anatomical profile rather than mere isolated fragments.”
The paleontological investigation identified a continuous dorsal feature commencing as a fleshy protuberance along the neck and trunk, which then transitioned posterior to the hips into an unsegmented row of dorsal spines extending down the tail, with each spine precisely aligned with a vertebral segment and interlocking with its neighbors.
The caudal and ventral regions displayed the most substantial polygonal scales; however, the majority comprised minute, pebble-like scales measuring merely 1-4 mm in diameter, a surprisingly small dimension for a dinosaur that attained lengths exceeding 12 meters (40 feet).
The presence of preserved wrinkles across the ribcage suggests that the integument of this hadrosaur was notably thin.
The hind limbs of the larger ‘mummy’ yielded the most significant revelation: the presence of hooves.
The distal extremities of each of the three metatarsals were encased within wedge-shaped hooves possessing a flattened plantar surface, akin to those found in equids.
The research cadre employed computed tomography (CT) scans of the specimen’s pedal elements and three-dimensional imagery of the most intact hadrosaur footprint dating from the same geological epoch, facilitating a precise overlay of the former onto the latter.
By integrating data derived from both these sources, they were able to achieve an accurate reconstruction of the hind foot’s morphology.
In contrast to the forelimb, which made contact with the substrate solely via its unguals, the hind feet possessed a fleshy plantar cushion situated posterior to the hooves.
“These hadrosaurian ‘mummies’ exhibit a multitude of remarkable ‘firsts’ – the earliest documented hooves in a terrestrial vertebrate, the first definitively identified hooved reptile, and the inaugural quadrupedal animal with distinct forelimb and hind limb postures, all possessing hooves,” emphasized Professor Sereno.
The researchers’ publication detailing these findings was released today in the esteemed scientific journal Science.
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Paul C. Sereno et al. 2025. Duck-billed dinosaur fleshy midline and hooves reveal terrestrial clay-template ‘mummification.’ Science, published online October 23, 2025; doi: 10.1126/science.adw3536
