Scientists discover dinosaur 'mummies' with hoofs like a horse

It’s been more than 60 million years since duck-billed dinosaurs roamed around what is now known as western North America.

Or, more accurately, since they clomped around. On their hoofs. 

This, according to a new study of “dinosaur mummies” — fossils in which the external anatomies of dinosaurs are rendered in incredible detail onto thin layers of ancient clay. 

It marks the first time hoofs have been found on a dinosaur or, in fact, any reptile. But the researchers behind the discovery expect more will turn up, now that people know to look for them.

“I think people's antennae will be up now to try and make sure there's nothing there when they're excavating,” University of Chicago paleontologist Paul Sereno, the study’s lead author, told As It Happens host Nil Köksal.

The findings, published in the journal Science, paint the most complete picture to date of what duck-billed dinosaurs actually looked like.

What’s more, the study unravels the long-standing mystery of how these so-called dinosaur mummies formed in the first place. 

Duck-billed dinosaurs were far more common than their more famous contemporaries of the Cretaceous Period, like the apex predator Tyrannosaurus, or horned dinosaur Triceratops.

In fact, these nearly three-metre long plant eaters were a favourite meal of the T. Rex. 

Also known as Edmontosaurus — because the first fossils were discovered in southern Alberta  — they roamed together in giant herds, grazing on plants,  much like modern-day cows, sheep and goats.

Also like today’s grazing mammals, these dinos developed hoofs, structures that protected their toes, supported their weight, offered traction and absorbed shock from the impact of all that walking — and running for their lives.

"It's remarkably like a later equine or horse hoof, or something that you might see on a relative, a tapir or a rhino,” Sereno said. 

“There's a shield around the outside, and then sort of a soft core on the bottom side that really resembles the mammalian hoofs that evolved so much later.”

It’s an example of a phenomenon known as convergent evolution, in which different organisms independently evolve similar features  — like the wings of birds, bats and the extinct  flying reptiles called pterosaurs — while adapting to similar  environments or ecological niches.