New Discoveries Reveal Stunning Details of Edmontosaurus Mummies

Paleontologists have made significant strides in understanding the duck-billed dinosaur, Edmontosaurus annectens, with the discovery of two new mummies in Wyoming. Led by Paul C. Sereno, a professor of organismal biology at the University of Chicago, the team unearthed these specimens in the same area where fossil collector C.H. Sternberg first discovered the species back in 1908. The findings have provided an unprecedented glimpse into the dinosaur’s anatomy, revealing details previously unknown.

The initial skeleton of Edmontosaurus, known as the “AMNH mummy,” was housed at the American Museum of Natural History in New York. It offered insights into the dinosaur’s appearance through scaly skin imprints in the surrounding sediment. More than a century later, Sereno’s team has now unveiled further details about the dinosaur’s anatomy, including the size of its scales and the arrangement of spikes on its tail.

Revisiting Historical Interpretations

The representation of Edmontosaurus has evolved considerably over the years. The first illustration, created in 1909 by renowned paleoartist Charles R. Knight, depicted the dinosaur inaccurately, extending a crest along its entire body based on incomplete evidence. Later, in 1984, paleontologist Jack Horner contributed new findings of tail spikes, but his interpretation also had inaccuracies.

Sereno’s team meticulously retraced Sternberg’s steps to locate where the original specimens were found. This process was challenging, as many of the landmarks mentioned in Sternberg’s notes no longer exist. By engaging with local farmers, the researchers pinpointed the “mummy zone,” an area rich in Cretaceous fossils.

“Understanding geology is crucial to finding dinosaurs,” Sereno noted, emphasizing that the unique conditions in this zone enabled the exceptional preservation of the mummies.

Unraveling the Mystery of Clay Templating

The fossils are located within the Lance Formation, known for its high rate of sedimentation during the last three million years of the Cretaceous period. Sereno suggests that frequent flooding from a nearby river contributed to this phenomenon. This flooding likely buried the dinosaurs, preserving them through a process known as clay templating.

As Sereno explained, “Clay templating occurs when clay adheres to the skin of organisms, creating a thin mask that reveals their appearance.” While this preservation method is familiar to researchers studying deep-sea organisms, its application to large dinosaurs was previously unconsidered.

The recent discoveries included two additional Edmontosaurus skeletons surrounded by remarkably thin clay masks, providing an accurate depiction of how these dinosaurs appeared.

The analysis employed cutting-edge imaging technologies, such as CT scans and photogrammetry, allowing the team to create a detailed model of the dinosaur’s skin. The updated findings revealed changes to the crest, the arrangement of spikes, and even the presence of hooves.

Surprisingly, it was determined that the dinosaur had singular, central hooves on its forelegs, resembling those of modern equines. The hind legs featured three wedge-shaped hooves, akin to the structure found in contemporary rhinoceroses.

Sereno remarked on the importance of these findings, stating, “These mummies have preserved many ‘firsts’ in evolutionary history, including the earliest documented hooves in land vertebrates.”

As the team continues their research, they are also investigating other remarkable finds in the mummy zone. “When I first explored this area, I discovered a T. rex embedded in a concretion,” Sereno shared, highlighting the exciting potential of future studies.

Two additional mummies, including a Triceratops, are currently under examination. The preservation of the T. rex, found in a lifelike pose, raises intriguing questions about its burial conditions, suggesting it might have been covered alive.

In contrast, the Edmontosaurus specimens were likely deceased for up to a week before being buried, which could enhance the accuracy of the T. rex reconstruction due to less decay to account for.

Sereno expressed his enthusiasm for the ongoing discoveries, particularly concerning the Triceratops. “We have already identified that its scales are substantially larger than those of the Edmontosaurus, with a significantly thicker skin,” he noted, indicating potential differences in physiology between the two species.

The research team anticipates publishing their findings in upcoming papers, contributing to an ever-expanding understanding of these remarkable dinosaurs. As Sereno affirmed, “We are in the age of discovery, and there is much more to come.”