Wyoming’s Dinosaur Mummies Reveal New Insights on Edmontosaurus

A remarkable discovery in Wyoming has transformed our understanding of the duck-billed dinosaur, Edmontosaurus annectens. Initially unearthed in 1908 by fossil collector C.H. Sternberg, this large herbivore’s skeleton, known as the “AMNH mummy,” has provided a glimpse into its ancient life. Recent research led by Paul C. Sereno, a professor at the University of Chicago, has unveiled two additional Edmontosaurus mummies, offering unprecedented detail about the dinosaur’s external anatomy.

The findings stem from a site in east-central Wyoming, where Sereno’s team retraced Sternberg’s original excavation route. This effort led to the identification of the “mummy zone,” an area rich in Cretaceous fossils, spanning less than 10 kilometers in diameter. The region, characterized by a unique geological formation, is pivotal for understanding the conditions that allowed for such extraordinary preservation.

Uncovering the Mystery of Edmontosaurus

The study of Edmontosaurus has evolved significantly over the past century. The first reconstruction by paleoartist Charles R. Knight in 1909 inaccurately depicted the dinosaur with a crest extending along its entire body. Subsequent interpretations, including one by influential paleontologist Jack Horner in 1984, continued to shape public perception but were also flawed. Horner’s depiction of the dinosaur included spikes on the tail, which were misrepresented in his reconstruction due to the poor condition of the specimen.

Sereno’s current research has provided a more accurate representation of Edmontosaurus, revealing details such as the arrangement of scales and spikes on its tail. The newly discovered mummies were preserved in a layer of clay less than one millimeter thick, allowing for the creation of a detailed model of their skin and anatomy using advanced imaging techniques like CT scans and photogrammetry.

Insights from the Mummy Zone

The fossils were located in the Lance Formation, a geological formation known for its rich fossil record, which dates back to the last three million years of the Cretaceous period. Sereno indicated that the formation’s thickness increases dramatically within the mummy zone, suggesting high sedimentation rates likely due to frequent flooding from a nearby river. These floods buried dinosaurs quickly, preserving their bodies in a process known as clay templating, which creates a thin layer of sediment that captures the animal’s external features.

The analysis of the Edmontosaurus mummies has led to several surprising revelations. Notably, the dinosaur’s legs were equipped with hooves, a discovery that challenges previous assumptions about the evolution of such features. The hooves were found to be similar in structure to those of modern equines, indicating that this characteristic was not exclusive to mammals.

Sereno’s team highlighted the small size of the scales, which measured just 1 to 4 millimeters across, demonstrating a level of detail previously unobserved in large dinosaurs. The skin was also found to be remarkably thin, with the imaging techniques revealing wrinkles that suggest a highly flexible and delicate exterior.

The latest findings have prompted further exploration in the mummy zone, where Sereno’s team also discovered mummies of a T. rex and a Triceratops. Each specimen offers unique insights into the physiology of these ancient creatures. The T. rex was preserved in a life-like pose, suggesting it may have been buried alive, while the Triceratops exhibited significantly larger scales and thicker skin compared to Edmontosaurus.

As Sereno concluded, “We are in the age of discovery,” suggesting that ongoing research in this rich fossil landscape will continue to yield fascinating insights into the lives of these ancient animals. The findings represent not just an evolution in our understanding of Edmontosaurus but also highlight the complexities of dinosaur physiology and behavior during the Cretaceous period.

This study, published in Science, marks a significant advancement in paleontological research and promises to reshape our understanding of dinosaur evolution and diversity in the late Cretaceous.