Wyoming Fossils Preserve Rare 'Mummified' Edmontosaurus
The Facts
- Specimens of Edmontosaurus annectens, first discovered in eastern Wyoming in 1908, have been reexamined by paleontologists at the University of Chicago. A paper published last week in Science shows the fossils preserve not only bones but also detailed impressions of skin, spikes and hooves beneath a thin clay coating.
- The fossils — one a late juvenile and the other an early adult — were preserved through a process called "clay templating," where a thin biofilm on decaying carcasses electrostatically attracted clay minerals from surrounding sediment to form masks less than one millimeter thick.
- These dinosaur "mummies" revealed that Edmontosaurus annectens had a fleshy crest running along the neck and trunk that transitioned into an interdigitating spike row extending down the tail, with each spike positioned over individual vertebrae.
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The Spin
Narrative A
Wyoming's Edmontosaurus "mummies" give scientists the first complete, fleshed-out view of a large dinosaur. They also establish a blueprint for future research and methodologies — including targeted searches for similarly preserved specimens, biomechanical modeling using reliable external boundaries and studies of clay templating in fossilization.
Narrative B
This is beyond a simple dinosaur discovery. Wyoming's "mummies" have rewritten evolutionary history altogether. These 66-million-year-old Edmontosaurus fossils show that dinosaurs evolved hooves millions of years before mammals, making them the first land vertebrates to develop this key adaptation for efficient movement. The discovery offers unprecedented insight into how major evolutionary innovations can emerge far earlier than previously believed.
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