Anytime someone finds a dinosaur fossil it is a big deal and very exciting, but some dinosaurs are better preserved than others. Recently, two mummified dinosaurs were found in the Badlands of Wyoming, providing scientists with an unprecedented picture of what these ancient animals looked like.

About 66 million years ago, these two duck-billed dinosaurs, known as Edmontosaurus annectens, were preserved via an extremely rare event that helped to keep them largely intact. This method of preservation is called clay templating, and in order for it to happen, a number of things have to go precisely right at the time of their death.

First, the dinosaurs have to be in the right environment where a very thin layer of clay can cover them at or shortly after they die. Dr. Paul Sereno, PhD, is a professor of Organismal Biology and Anatomy at UChicago.

In a statement about the study he wrote and published in the journal Science on these remains, he explains:

“This is a mask, a template, a clay layer so thin you could blow it away. It was attracted to the outside of the carcass in a fluke event of preservation.”

After the clay is in place, it would bake in the hot sun for a short period of time until the bodies are covered in water by a flash flood. At that time, a biofilm would cover the surface of the bodies (and the clay) and pull the clay out of the wet sediment through an electrostatic process.

At any point in this process, things could have gone wrong and either left behind a normal fossil, or had the body destroyed entirely in some fashion. Fortunately for modern paleontologists, the conditions were absolutely perfect and they left behind some of the best-preserved remains of dinosaurs ever discovered.

The two mummified dinosaurs likely died at the same time due to the same event, leaving them preserved for millions of years until modern scientists could study them. The researchers have been gathering vast amounts of new information from these two samples, including something that has surprised many.

This species of dinosaur has three toes on its hind legs, each of which was capped with a hoof. The hoof, which is not unlike that of a horse or a cow, is the first example of this trait on a reptile.

Sereno discusses the finds:

“There are so many amazing ‘firsts’ preserved in these duck-billed mummies. The earliest hooves documented in a land vertebrate, the first confirmed hooved reptile, and the first hooved four-legged animal with different forelimb and hindlimb posture.”

While these discoveries are exciting on their own, there is likely a lot more that researchers will learn from these remains.

In addition, these two samples prove that the conditions in this location were good for preserving the remains of dinosaurs, so it is likely that more fossils will be found, even if they may not be as well-preserved as these two.

Sereno talks about the find:

“We’ve never been able to look at the appearance of a large prehistoric reptile like this – and just in time for Halloween. It’s the first time we’ve had a complete, fleshed-out view of a large dinosaur that we can really feel confident about. The Badlands in Wyoming where the finds were made is a unique ‘mummy zone’ that has more surprises in store from fossils collected over years of visits by teams of university undergrads.”

It will be exciting to see what other discoveries are made at this location.

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