Bony knobs studding the head and snout of Akainacephalus johnsoni, a type of armored dinosaur called an ankylosaurid, are similar to those of Asian ankylosaurids. That was a surprise, says Jelle Wiersma, a paleontologist at James Cook University in Townsville, Australia.
He and Randall Irmis, a paleontologist at the Natural History Museum of Utah in Salt Lake City, had expected the 76-million-year-old skeleton, unearthed in 2008 in Utah’s Grand Staircase-Escalante National Monument, to have a smoother dome typical of North American ankylosaurids.
These armored dinos first appeared in Asia around 125 million years ago and had reached western North America by about 77 million years ago. One other known North American ankylosaurid, a different species found in New Mexico that’s 3 million years younger than the newfound dino, also has a rugged noggin comparable to A. johnsoni’s.
The new find adds to evidence that at least two types of ankylosaurids migrated from Asia to North America during the late Cretaceous, possibly via a land bridge between the continents, the researchers report July 19 in PeerJ.
Along with a complete skull, paleontologists uncovered an intact tail club, as well as many vertebrae, limb bones and bony plates. A. johnsoni is the most complete ankylosaurid fossil yet found in the southwestern United States, the researchers say.
Source : sciencenews