Consequently, the Edmontosaurus image underwent another update. Some of the modifications were quite remarkable.
Graceful giants
Sereno’s group examined the recently unearthed Edmontosaurus mummies using an array of contemporary imaging methods such as CT scans, X-rays, photogrammetry, and others. “We constructed a precise model of the skin and wrapped it around the skeleton—many of these technologies weren’t even accessible a decade ago,” Sereno remarks. The outcome was a revised Edmontosaurus image featuring alterations to the crest, spikes, and skin texture. Perhaps most unexpectedly, it introduced hooves on its legs.
It turned out both Knight and Horner had partially accurate ideas about the appearance of Edmontosaurus’ back. The fleshy crest, as illustrated by Knight, indeed originated at the top of the head and extended backward along the spine. The distinction was that there was a moment where this crest transitioned into a series of spikes, as depicted in Horner’s representation. The spikes were akin to those observed on contemporary chameleons, where each spike is directly linked to the corresponding vertebra beneath it.
“Another astonishing aspect of Edmontosaurus was the diminutive size of its scales,” Sereno states. Most of the scales measured only 1 to 4 millimeters in diameter. They became slightly larger towards the tail’s end, but even there, they did not exceed 1 centimeter. “Such scales can be noticed on a lizard, and we’re discussing a creature comparable in size to an elephant,” Sereno adds. The skin adorned with these minuscule scales was also remarkably thin, a conclusion the team drew from the wrinkles observed in their imaging.
Then came the hooves. “In a hoof, the nail encircles the toe and wraps, wedge-shaped, around its base,” Sereno clarifies. The Edmontosaurus possessed singular, central hooves on its front legs featuring a “frog,” a triangular, malleable structure on the underside. “They resembled equine hooves quite a bit, so evidently these weren’t solely a mammalian creation,” Sereno comments. “Dinosaurs had them.” The hind legs, which bore most of the animal’s weight, however, had three wedge-shaped hooves encircling three digits and a fleshy heel at the rear—a design seen in present-day rhinos.
