Dinosaur ‘Mummies’ Unveiled as Perfect Clay Masks in Wyoming Discovery

In a groundbreaking study, paleontologists have revealed that what were once thought to be well-preserved dinosaur “mummies” in Wyoming’s Lance Formation are actually intricate clay masks. This discovery sheds light on the preservation processes of ancient specimens and offers new insights into the appearance and anatomy of the Edmontosaurus annectens, a duck-billed dinosaur that roamed the Earth over 66 million years ago.

The Lance Formation, a site located in eastern Wyoming, is known for its rich deposits of prehistoric fossils. Within a small area of less than 10 kilometers (approximately 6 milesScience, aims to elucidate the characteristics of these fossils and the methods of their preservation.

The history of these discoveries dates back to the early 1900s when fossil hunter Charles Sternberg uncovered two specimens of Edmontosaurus. These skeletons were notable for their pristine condition, with what appeared to be large patches of skin and a fleshy crest along the dinosaur’s neck. Sternberg’s findings were later supported by H.F. Osborn at the American Museum of Natural History. Sereno recalls this initial discovery, stating it was “the greatest dinosaur mummy — until maybe the juvenile that we found” in 2000.

Sereno’s team analyzed two additional specimens of Edmontosaurus found in the Lance Formation during 2000 and 2001. Using advanced techniques such as CT scanning, 3D imaging, and electron microscopy, they examined these mummies in detail. Surprisingly, the researchers found no remnants of soft tissue. Instead, they discovered a thin layer of clay, measuring less than one-hundredth of an inch thick, covering the animals’ skin. This clay layer created an astonishingly lifelike impression of the dinosaurs.

Sereno proposes that the term “rendering” is more accurate than the previously used “impression” to describe the detailed clay formations found on these specimens. The study outlines how climatic conditions during the Late Cretaceous Period contributed to this unique preservation method. The dinosaurs likely died during a drought, and after being exposed to the sun, their carcasses were quickly buried by a flash flood. Bacteria that developed on the decaying bodies attracted clay particles from the surrounding sediment, creating the precise clay masks that have fascinated paleontologists.

Dr. Anthony Martin, a professor at Emory University, noted the significance of these findings, stating that clay minerals can faithfully reproduce biological surfaces, such as skin and other soft tissues. This natural process effectively preserves the detailed morphology of the dinosaurs.

Dr. Stephanie Drumheller-Horton, a vertebrate paleontologist at the University of Tennessee, Knoxville, emphasized the importance of understanding how these fossils formed. “If we can understand how and why these fossils form, we can better target where to look to potentially find more of them,” she explained.

The analysis of the two recently discovered mummies allowed Sereno’s team to develop a comprehensive portrait of what Edmontosaurus may have looked like. Their findings suggest that this dinosaur could grow over 12 meters (approximately 40 feetEdmontosaurus possessed hooves, a trait previously thought to be exclusive to mammals. This finding makes it the oldest land animal confirmed to have hooves and the first known hooved reptile. Sereno humorously remarked, “Sorry, mammals, you didn’t invent it,” while acknowledging that while footprints suggested the presence of hooves, seeing the evidence was a revelation.

These discoveries not only enhance our understanding of Edmontosaurus but also open new avenues for paleontological research. As scientists continue to explore the “mummy zone” in Wyoming, they hope to uncover more about the life and environment of these ancient creatures. The implications of this research could significantly influence future fossil studies and the methods used to analyze dinosaur remains.