Discovery: First-ever 'mummified' and hoofed dinosaur discovered in Wyoming badlands

 New dinosaur discoveries fascinate me, and as a kid I collected plastic dinosaur figures and read every book I could find about them. As an adult, I love reading about new fossil discoveries and some of the higher-level science books. Today's blog is about a dinosaur "First." 

(Image: Edmontosaurus annectens as it appeared in life. | Credit: Artwork by Dani Navarro)

First-ever 'mummified' and hoofed dinosaur discovered in Wyoming badlands 

LIVE SCIENCE By Patrick Pester published October 29, 2025

Researchers have unearthed two dinosaur "mummies" in the badlands of Wyoming, confirming duck-billed dinosaurs had hooves, alongside a string of other discoveries.

Two extremely rare dinosaur "mummies" found in the badlands of Wyoming are the first examples of hoofed reptiles, according to a new study.

Researchers discovered the pair of 66 million-year-old duck-billed dinosaur (Edmontosaurus annectens) skeletons complete with skin, spikes and hooves, as if the creatures had been naturally mummified.

The fossils aren't true mummies, as their original tissues have been replaced with rock, but they give scientists an unprecedented look at duck-billed dinosaur biology, confirming they had hooves. The researchers reported their findings Oct. 23 in the journal Science.

"It's the first time we’ve had a complete, fleshed-out view of a large dinosaur that we can really feel confident about," study senior author Paul Sereno, a professor of organismal biology and anatomy at the University of Chicago, said in a statement.

(Image:  This mummified duck-billed dinosaur fossil is a juvenile Edmontosaurus annectens, nicknamed "Ed Jr." (Image credit: Photograph courtesy of Tyler Keillor/Fossil Lab)) 

Duck-billed dinosaurs used their hooves to stomp through mud at the end of the Cretaceous period (145 million to 66 million years ago). They lived alongside other large dinosaurs, such as Tyrannosaurus rex and Triceratops, just before the age of dinosaurs came to a crashing end when a massive asteroid hit Earth and wiped them all out (except for birds).

Dinosaur mummies are exceptionally preserved fossils that contain a clay copy of dinosaur skin and other organic tissues. Several of these fossils were discovered in Wyoming in the early 1900s, which inspired the new research. Sereno and his colleagues found the two new specimens by tracking down the locations of the historical discoveries, using old photographs and letters, and mapping out what they described as a "mummy zone."

One of the newly discovered Edmontosaurus specimens, nicknamed "Ed Jr.," was a late juvenile and estimated to be about 2 years old at the time of its death. The other specimen, nicknamed "Ed Sr.," was an early adult about 5 to 8 years old when it perished.