Armored Dinosaur Found in Utah Evolved From Asian Ancestors

Scientists believe the dinosaur Akainacephalus johnsoni. recently discovered in Utah, evolved from ancestors in Asia. (Andrey Atuchin/Natural History Museum of Utah)

(CN) – Scientists at the Natural History Museum of Utah on Thursday revealed the discovery of fossils belonging to a bony-tailed dinosaur with armor-like skin that walked the earth 76 million year ago.

Paleontologists at the museum said they’ve unearthed fossils belonging to Akainacephalus johnsoni. The medium-sized, herbivorous dinosaur evolved from a line of dinosaurs called anklosaurids which lived in Asia and western North America during the Late Cretaceous Period.

Walking on four legs and using leaf-shaped teeth to eat plants, the dinosaur also had a large mass at the end of its tail which was used for crushing things and for self-defense.

Akainacephalus lived during the upper Campanian stage of the Late Cretaceous Period, which spanned from approximately 84 million to 72 million years ago. Akaina comes from the Greek word for spike or thorn while cephalus comes from the word for head.

The museum said it took almost four years to fully prepare all of the fossils for display. Museum volunteer Randy Johnson helped put the fragments of the skull together, and now is the dinosaur’s namesake.

“I never thought that I would have the opportunity to actually work on fossils that could be important for paleontologists,” said Johnson, a retired chemist. “I’m getting the opportunity to work on a large variety of fossils and consult with top paleontologists – it’s like a dream second career. I couldn’t believe it when they told me they are naming the ankylosaur after me, a once in a lifetime honor.”

When paleontologists discovered Akainacephalus, it was covered from head to tail with bony and spiked armor plates called osteoderms.

Spiky bony armor covering the skull and snout align more closely with Asian ankylosaurids, scientists said. They expected the dinosaur to look like other North American ankylosaurid dinosaurs from the Late Cretaceous with smooth bony armor on the skull.

“A reasonable hypothesis would be that ankylosaurids from Utah are related to those found elsewhere in western North America, so we were really surprised to discover that Akainacephalus was so closely related to species from Asia,” said Randall Irmis, co-author of the report on the fossils.

Though ankylosaurids originated in Asia between 125 and 100 million years ago, they do not appear in the western North American fossil record until about 77 million years ago, the museum said.

Akainacephalus once roamed the southern part of Laramidia, a landmass on the western coast of a shallow sea that flooded the central region and split North America in two, which caused isolation between different animals.

Report author Jelle Wiersma said brief intervals of lower sea levels exposed the Beringian land bridge, allowing dinosaurs and other animals to move between Asia and North America.

“It is always exciting to name a new fossil taxon, but it is equally exciting if that taxon also provides additional insights into the bigger picture of its life, such as its diet or aspects of its behavior, and the environment it lived in,” said Wiersma.

The movement from Asia into western North America resulted in two different types of ankylosaurid dinosaurs: ones that evolved with flatter skull armor and ones possessing spiky, bony skull armor Wiersma said.

The set of fossils was discovered in 2008 in a remote area of Grand Staircase-Escalante National Monument in Kane County, Utah.

Bureau of Land Management employee Scott Richardson was the first to discover the site – called the Kaiparowits Formation – which is made up of sedimentary rocks deposited by rivers and streams.

The dinosaur was found next to fossils of several other animals including a duck-bill dinosaur Gryposaurus, a recently-described species of turtle Arvinachelys, and a still unnamed relative of alligators.

All fossils will be permanently housed in the collections of the Natural History Museum of Utah at the Rio Tinto Center in Salt Lake City.

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