New Findings on Edmontosaurus Mummies Transform Dinosaur Understanding

New discoveries in Wyoming have significantly enhanced our understanding of the herbivorous dinosaur, Edmontosaurus annectens. A research team led by Paul C. Sereno, a professor at the University of Chicago, unearthed two remarkably preserved mummies of this dinosaur species, revealing intricate details of its external anatomy.

The original specimen of Edmontosaurus was discovered in 1908 by fossil collector C.H. Sternberg in east-central Wyoming. Housed at the American Museum of Natural History, this skeleton was nicknamed the “AMNH mummy” and provided the first glimpse of what this dinosaur may have looked like through its imprinted scaly skin. More than a century later, Sereno’s team returned to the same site, uncovering new specimens that have allowed for a more accurate representation of the dinosaur’s appearance.

Revising Historical Interpretations

Since the initial discovery, interpretations of Edmontosaurus have evolved. The first artistic depiction was created in 1909 by renowned paleoartist Charles R. Knight. While Knight made some accurate observations, he mistakenly illustrated a continuous crest along the dinosaur’s body, as he based his work on an incomplete specimen. Subsequent interpretations, including one by influential paleontologist Jack Horner in 1984, attempted to adjust the image but also contained inaccuracies.

“Over time, we ended up with many different, competing visions of Edmontosaurus,” Sereno stated. “But I think now we finally nailed down the way it truly looked.” The research team meticulously retraced Sternberg’s steps, relying on his notes and local interviews, until they reached what they termed the “mummy zone,” an area rich with Cretaceous fossils within a 10-kilometer radius.

Geological Insights and Preservation Techniques

The newly discovered fossils are located within the Lance Formation, a geological formation from the final million years of the Cretaceous period, stretching across parts of North Dakota, South Dakota, Wyoming, Montana, and into Canada. “The formation is roughly 200 meters thick, but when you approach the mummy zone, it suddenly goes up to a thousand meters thick,” Sereno explained, attributing this phenomenon to high sedimentation rates likely caused by regular flooding.

This unique sedimentation process, described as “clay templating,” preserves a thin layer of the dinosaurs’ skin, providing an unprecedented glimpse into their appearance. “It’s called clay templating, where the clay sticks to the outside of the skin and preserves a very thin layer,” Sereno noted. This technique has previously been observed in deep-sea invertebrates but had not been documented in large dinosaurs.

The research team employed advanced imaging technologies, including CT scans and photogrammetry, to analyze the newly discovered mummies. “We created a detailed model of the skin and wrapped it around the skeleton,” Sereno added. The results revealed significant updates to the Edmontosaurus image, including changes to the crest, spikes, and skin appearance.

One of the most surprising findings was the presence of hooves on the dinosaur’s legs. The forelimbs featured singular, central hooves reminiscent of equine hooves, while the hind limbs displayed three wedge-shaped hooves, similar to those of modern-day rhinoceroses. “Dinosaurs had them,” Sereno emphasized, noting that these findings represent an evolutionary milestone.

Sereno’s team also discovered additional specimens, including a T. rex and a Triceratops, both of which are currently under examination. The T. rex mummy was remarkably preserved in a life-like pose, suggesting it may have been buried alive, while the Triceratops presented a unique opportunity to compare skin textures and scale sizes with the Edmontosaurus.

As Sereno concluded, “We are in the age of discovery. There are so many things to come. It’s just the beginning.” The upcoming publications on these findings promise to shed further light on the remarkable diversity and evolutionary adaptations of these ancient creatures.