Recent research has unveiled that the so-called dinosaur “mummies” found in the Lance Formation of eastern Wyoming are not actual preserved skin but rather incredibly detailed clay masks. This area, known for its rich deposits of prehistoric fossils, has yielded several well-preserved dinosaur specimens, including the giant duck-billed dinosaur, Edmontosaurus annectens.
The term “mummy zone,” coined by paleontologist Paul Sereno and his colleagues, refers to a specific region less than 10 kilometers (6 miles) across that has produced remarkable fossil discoveries. These specimens showcase intricate details of skin texture, hooves, and spikes. The initial discovery in the early 1900s by fossil hunter Charles Sternberg revealed two pristine Edmontosaurus specimens, leading to significant insights about the dinosaur”s anatomy.
Sereno, who is the lead author of the recent study, noted that previous researchers, including H.F. Osborn, recognized that the skin impressions were not dehydrated like those found in Egyptian mummies but were left wondering about their preservation method. The new study seeks to clarify this mystery, providing a framework for understanding how these ancient creatures might have appeared.
To investigate the specimens found between 2000 and 2001, Sereno”s team employed advanced technologies such as CT scanning, 3D imaging, and electron microscopy. Their thorough analysis revealed a thin layer of clay, measuring less than one-hundredth of an inch thick, that coated the dinosaur”s skin. This finding led Sereno to propose a new term, “rendering,” to describe the clay”s precise molding of the outer body surfaces.
During the Late Cretaceous Period, when Edmontosaurus thrived in what is now the American West, climatic conditions fluctuated between droughts and monsoonal rains. It is believed that the original specimen discovered by Sternberg succumbed to drought, followed by a flash flood that buried the carcasses in sediment. Decaying bodies would have developed a bacterial film that attracted clay from the surrounding environment, ultimately preserving the fine details of the skin.
Dr. Anthony Martin from Emory University commented on the significance of this clay preservation, stating that clay minerals can adhere to biological surfaces, creating detailed molds of features such as skin and soft tissues. This scientific advancement helps paleontologists interpret the physical characteristics of these ancient creatures better.
Furthermore, Sereno”s team used their findings from the two recently uncovered specimens to reconstruct a more accurate depiction of the Edmontosaurus. Their analysis revealed that this dinosaur, reaching lengths of over 12 meters (40 feet), had a fleshy crest along its neck and back, along with a row of spikes down its tail. The thin skin exhibited delicate wrinkles and is dotted with small, pebble-like scales, indicating it had hooves—a trait previously attributed only to mammals.
Sereno humorously pointed out, “Sorry, mammals, you didn”t invent it,” highlighting the groundbreaking nature of this discovery. The study was published in the journal Science, advancing our understanding of how these fascinating dinosaurs looked and how they were preserved in the geological record.
