Wyoming Dinosaur 'Mummies' Reveal Hoofed Feet and Unique Preservation Process

Recent excavations in Wyoming's 'mummy zone' have uncovered two Edmontosaurus fossils with exceptionally preserved skin and the first known instance of hooves in dinosaurs. These findings, detailed in the journal Science, provide new insights into dinosaur anatomy and the fossilization process.

The specimens, a juvenile and an adult nicknamed 'Ed Jr.' and 'Ed Sr.', were found in a six-mile-wide area known for yielding well-preserved dinosaur remains. The adult specimen showcases the earliest known occurrence of hooves in any reptile, suggesting that Edmontosaurus evolved these structures millions of years before mammals.

The preservation process involved a thin clay layer, approximately one-hundredth of an inch thick, that formed over the skeletons after death. This clay templating, facilitated by microbial activity during decay, captured detailed impressions of the dinosaurs' external features, including skin and hooves.

Paul Sereno, a paleontologist at the University of Chicago and lead author of the study, stated, "We're seeing the full profile of the dinosaur for the first time."

These discoveries not only enhance understanding of Edmontosaurus anatomy but also expand knowledge of fossilization processes, indicating that exceptional soft-tissue preservation can occur in oxygen-rich environments through microbial mediation.