Two dinosaur “mummies” found in Wyoming (United States) reveal unique details of their external anatomy and an unexpected detail: that they had hooves on their feet, something never seen before.
“We’re seeing the full profile of the dinosaur for the first time. We’re sure what it looked like,” says paleontologist Paul Sereno of the University of Chicago, who led a new study published in the journal Science.
A duck-billed dinosaur
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The two specimens found are of the edmontosaur, a herbivorous species with a “duck bill” that lived about 66 million years ago, in the late Cretaceous period, at the end of the era of the dinosaurs.
One of them was a 12-meter adult and the other, a two-year-old juvenile, half that size.
It was the “cow of its time”
According to Sereno, it is by far “the most common dinosaur” in its ecosystem. “They had giant herds, it is the cow of its time,” he says. Edmontosaurus lived with other famous dinosaurs such as the triceratops, the ankylosaurus and the tyrannosaurus rex.
Due to its size, it would probably have been hunted by the famous predator: “There is no doubt that it is on the menu. It was not easy to hunt. That’s why something the size of the tyrannosaurus was needed,” he adds.
Details of its appearance exceptionally preserved
Its external contours were preserved thanks to a very thin layer of clay, barely 0.025 cm, that formed after his death. The skin, scales and shape of the feet were printed in unprecedented detail.
“Every time we find one, we discover a treasure trove of information about these animals,” says Stephanie Drumheller, a paleontologist at the University of Tennessee, who was not involved in the study.
Why are they called “dinosaur mummies“?
Although they are called “mummies,” they do not contain actual DNA or tissues. In reality, they receive that term from other similar fossils found more than a century ago in the same site.
“They don’t look like Egyptian-style human mummies. And at least in our mummies, there is no DNA, there is no tissue, there is nothing. It is a clay mask,” explains Sereno.
First dinosaur with hooves
The most striking and unexpected finding is that Edmontosaurus developed hooves millions of years before modern mammals: “They are for hard land, for walking well—perhaps even running—on the surface,” Sereno points out.
This trait represents a case of convergent evolution, a phenomenon in which different animals develop similar adaptations, such as the wings of birds, bats and extinct pterosaurs.
The dinosaur walked on four legs when moving slowly and on two legs when running: “The only animal we can use as a comparison is the kangaroo,” adds the scientist.
Other relevant finds in the area
The fossils also show unique details of their skin. It is observed that it had small scales like pebbles. It is believed that both died from drought and were covered by a flash flood, which sealed their bodies in clay.
During the excavation in this dinosaur “mummy zone”, the team also found fossils of Tyrannosaurus rex and Triceratops, which will be studied later.
“Tyrannosaurus rex doesn’t even have scales. The fossil suggests that it could have feathers,” Sereno advances.
Edited by Jose Urrejola, with information from AP, Reuters, Science.
