Dinosaur ‘mummies’ prove some dinos had hooves
For the first time, paleontologists They successfully reconstructed the profile of two enormous duck-billed animals. dinosaursright down to their pebbled skin and unexpected hooves. Based in part on remains found decades ago in the badlands of Wyoming, this pair Edmontosaurus annectens The specimens were only preserved thanks to an extremely rare, delicate “mummification” process.
Meet duckbills
It is approximately 39 feet long and weighs approximately 6.2 tons, E. annectens It was one of the largest and most widespread dinosaurs in present-day North America during the Late Cretaceous period. At the same time Really One of the last examples of its kind. Fossil records dating back to 68 to 66 million years ago show that E. annectens it probably existed until the Cretaceous-Paleogene extinction event that wiped out all non-avian dinosaurs.
edmontosaurs It was probably quite remarkable to look at, with a long, low skull and one of the most distinctive duck-billed snouts of any hadrosaur. Although paleontologists had previously discovered various skeletal segments and more than 20 partially-complete skulls, they were unsure of its overall anatomy.
“Ed Jr.” Scaly skin on the back of the baby duck-billed dinosaur Edmontosaurus annectens, nicknamed Edmontosaurus annectens. Estimated to have been about two years old when he died, baby duckbill is the only baby dinosaur mummy ever discovered. Credit: Tyler Keillor/Fossil Lab
How does a dinosaur turn into a ‘mummy’?
To better understand the creature, a team led by University of Chicago anatomist Paul Sereno tracked the historical sites of previous dinosaur finds in east central Wyoming. Specifically, they identified a small area known for its “mummies,” including two new mummies. E. annectens Examples discovered by Sereno’s group; a late teenager and an early adult.
“The badlands in Wyoming where the finds were made are a unique ‘mummy site,'” Sereno said. he said in a statement.
These are not mummies in the traditional sense of the word. There are no organic remains, but there is dinosaur anatomy such as skin, hooves and spikes preserved in a submillimeter clay film during a process called clay templating. The making of one of these mummies requires what Sereno calls a “serendipity preservation event” that occurred immediately after the death and burial of a dinosaur.
“It’s a mask, a stencil, a layer of clay so thin you can blow it up,” he explained.
Sereno’s team used multiple imaging techniques, such as micro-CT scans and X-ray spectroscopy, to closely analyze how this process might occur. They believe the most likely scenario would begin with a flash flood covering a sun-dried dinosaur carcass. As the waters flow over the body, a biofilm on the animal’s skin electrostatically pulls the clay from the surrounding sediment, creating a delicate “template layer.” This layer preserved the surface underneath in three dimensions as the dinosaur’s organic material continued to decay before its skeleton eventually fossilized.
While the details of the dinosaur template are often unprecedented, they are also extremely precise; Experts at UChicago’s Fossil Laboratory spent hours clearing the clay boundary. Other team members continued to perform surface and CT imaging of the skeleton and studied the fossilized footprints. Final results announced in a study published October 23 Science offers a never-before-seen look at the dinosaur couple.
“The two samples complemented each other beautifully. For the first time, we could see the entire profile instead of scattered parts,” said Sereno.
Scene painting showing a duck-billed dinosaur while alive, based on mummies discovered in east-central Wyoming about 66 million years ago, documenting its scaly skin and hooves. It had a fleshy crest on its neck and torso, fleshy spikes on its hips and tail, and hooves that covered its hind toes. Credit: Dani Navarro
Single spikes, polygonal scales and hooves
Paleontologists were able to detect a continuous midline anatomical detail on it. E. annectens This starts as a crest along his neck and torso, before turning into a single row of spikes down his hips and tail. Each spike grew directly above and rested on a single corresponding vertebra. The dinosaur’s lower body and tail skin displayed larger polygonal scales, although most were the size of small pebbles. Usually dinosaurs this big E. annectens had larger scales. The wrinkles on his ribcage also indicate that his skin is thin.
But the most unexpected discovery is found in the larger mummy’s hind legs. Each contained three toes covered with a wedge-shaped, flat-bottomed hoof, similar to a horse. With additional examination of fossilized duckbill footprints from the same period, the team reconstructed the overall appearance. Now it seems E. annectens It walked with its front feet touching the ground only with its hooves, and its hind feet had a fleshy heel pad for support.
“There are many surprising ‘firsts’ preserved in these duck-billed mummies,” Sereno said. “The oldest documented hooves in a land vertebrate, the first attested ungulate reptile, and the first ungulate quadruped with distinct fore- and hindlimb posture.”
The authors of the study hope that other researchers will now be able to apply the methods described in their study to other dinosaur mummies. In the meantime, they plan to search around Wyoming for examples similar to their work.
