Wyoming's 'Mummy Zone' Yields Exceptionally Preserved Dinosaur Fossils

Paleontologists have unearthed two exceptionally preserved Edmontosaurus fossils in Wyoming's Lance Formation, providing unprecedented insights into dinosaur anatomy. These 66-million-year-old specimens, discovered by a team led by University of Chicago paleontologist Paul Sereno, include a young adult approximately 40 feet long and a juvenile about half that size.

The fossils exhibit a thin clay layer that preserved the contours of their skin and soft tissues, revealing features such as a fleshy crest along the neck and back, a row of spikes down the tail, and notably, hoof-like structures on their feet—the first ever observed in a dinosaur. Sereno noted that these hooves suggest convergent evolution with modern hoofed mammals, enabling efficient locomotion on hard terrain.

The discovery was facilitated by historical research and local knowledge. Sereno traced the original excavation site of a 1908 dinosaur mummy by consulting historical documents and engaging with local ranchers. A rancher's great-grandmother, who had served as the postmaster of the now-defunct town of Warren, Wyoming, provided crucial information that led to the rediscovery of the site.

These findings not only enhance the understanding of Edmontosaurus anatomy but also underscore the significance of the Lance Formation's 'mummy zone' in preserving Late Cretaceous ecosystems. The area has also yielded fossils of other dinosaurs, including Tyrannosaurus and Triceratops, suggesting a rich repository for future paleontological discoveries.