Scientists have uncovered some amazing new insights into a well-known dinosaur species from Wyoming. These are not just bones—they’re incredibly well-preserved fossils called mummies that show the animals almost as if they were alive. These discoveries are giving us a clearer picture of what these dinosaurs looked like, down to tiny details like their scales and even their hooves.

The Return to a Famous Find

The story begins over a century ago, in 1908, when a fossil collector named C.H. Sternberg found the first specimen of Edmontosaurus annectens in east-central Wyoming. This fossil became famous as the “AMNH mummy” because it was covered in preserved skin, giving scientists a rare look at the animal’s outer appearance. Back then, they only had a rough idea of what it looked like, mainly based on the bones and some skin impressions.

Fast forward more than 100 years, and a team led by paleontologist Paul Sereno returned to the same site. This expedition wasn’t easy because the exact location was lost to time, but with help from local farmers and old notes, they pinpointed a small area called the “mummy zone.” In this zone, they found not just one but two new Edmontosaurus mummies, each with skin and details perfectly preserved in a thin layer of clay. This allowed scientists to see the animal’s appearance in stunning detail, including the size of its scales and the arrangement of spikes along its tail.

How These Mummies Rewrite Dinosaur Looks

Over the years, scientists had different ideas about what Edmontosaurus looked like. The first artist’s impression, made in 1909, showed a creature with a long crest running along its back, based on the initial find. But that version was not entirely accurate because the original specimen lacked a tail, leading the artist to fill in gaps with imagination. Later, in 1984, paleontologist Jack Horner found evidence that the tail had spikes, not a crest, which led to a different reconstruction. This created a confusing picture, with multiple conflicting images of the dinosaur.

Sereno’s team finally set the record straight. They used modern imaging techniques like CT scans and 3D modeling to analyze the new mummies. What they found was that the crest started at the head and ran down the back but then transitioned into a row of spikes along the tail—similar to what some lizards have today. These spikes were small and rectangular, touching each other along the tail, creating a striking look that combines elements from previous versions.

One of the most surprising discoveries was the tiny size of the dinosaur’s scales. Most were just 1 to 4 millimeters across—tiny, especially for an animal as big as an elephant. The skin was incredibly thin and covered in these small scales, giving it a smooth, almost delicate appearance. And then there were the hooves. The team found that Edmontosaurus had hoof-like structures on both its front and back legs, similar to modern horses and rhinos. The front legs had single, wedge-shaped hooves with a rubbery “frog,” while the back legs had three hooves, supporting its weight more like a mammal than a reptile.

These findings are important because they show that some features we usually associate with mammals, like hooves, actually appeared in dinosaurs. Sereno calls this a “first”: the earliest evidence of a land vertebrate with hooves, and one with different limb postures on its front and back legs. It’s a big step forward in understanding how these creatures looked and moved.

More Fossil Surprises in the Same Area

The Wyoming mummy zone isn’t just about Edmontosaurus. Sereno’s team also found other remarkable fossils, including a well-preserved Tyrannosaurus rex and a Triceratops. These fossils are also being studied and will add to our picture of that ancient ecosystem. The T. rex, for example, was found in a very lifelike pose, frozen in time, which helps scientists understand how it might have looked and behaved.

All these discoveries show how much more there is to learn about dinosaurs. The Wyoming mummies are especially valuable because they offer a snapshot of these animals’ outer layers, something rarely preserved in fossils. Each new find helps fill in the gaps and correct old ideas, bringing us closer to understanding these incredible creatures that once roamed the Earth.

Inspired by

• https://arstechnica.com/science/2025/11/wyoming-dinosaur-mummies-give-us-a-new-view-of-duck-billed-species/

Sources

• conde.digital
• cnevids.com
• doi.org