In 1908, fossil hunter Charles Sternberg found a famous "dinosaur mummy" in eastern Wyoming.
More than 100 years later, scientist Paul Sereno from the University of Chicago wanted to see exactly where that discovery was made.
Old notes spoke of a town called Warren, Wyoming, but the town no longer appears on any map.
Sereno visited local ranches and met a family whose great-grandmother had been the postmaster of Warren.
Using her story about the position of the post office, Sereno calculated how far the 1908 site must be.
The area is now called the "mummy zone." Thick river sand covered the dinosaurs and made a very thin clay mask around their bodies.
This mask is only one-hundredth of an inch thick, but it keeps the shape of the skin, beak, and even tail spikes.
Sereno’s team examined two mummies of the duck-billed dinosaur Edmontosaurus: an adult called “Ed Sr.” and the only known juvenile, “Ed Jr.”
They could see the full body from head to toe, including a rhino-like hoof on each foot and rows of spikes on the tail.
The only detail still missing is the color of the animal’s skin.
As a child, Sereno saw the 1908 mummy in a New York museum. That visit made him choose a career in paleontology.
He now tells kids that many fossils are still waiting to be found. New generations will continue to uncover secrets about dinosaurs.