A new dinosaur has been discovered – or, at least its fossils were discovered – in the Kaiparowits Formation of Grand Staircase-Escalante National Monument in Utah. These fossils represent a new genus and species of ankylosaurid dinosaur, and have revealed new details about the diversity and evolution of this group of dinosaurs.
The ankylosaurids were a group of four-legged herbivorous armored dinosaurs with tails that contained bony clubs. They are believed to have originated in Asia between 125-100 million years ago, but did not appear in the western North American fossil record until roughly 77 million years ago. This new species, discovered by researchers from the University of Utah, lived 76 million years ago, during the Late Cretaceous period. It has been named Akainacephalus johnsoni after Randy Johnson, a dedicated museum volunteer who helped prepare the specimen, and is of no relation to the Hall of Fame pitcher Randy Johnson.
The fossil itself is the most complete skeleton of any ankylosaurid dinosaur found in the southwestern US, as it includes a complete skull, much of the vertebral column, a complete tail club, several fore and hind limb elements, and bony body armor that includes two neck rings and spiked armor plates. While the species was expected to look like other North American Late Cretaceous ankylosaurid dinosaurs, with smooth bony armor on the skull, the researchers’ findings indicate that this species’ defining features align more closely with Asian ankylosaurids – mainly due to it having more pronounced spikes on the skull.
Jelle Wiersma, the lead author of the study, suggests that the geographic distribution of Late Cretaceous ankylosaurids throughout the Western Interior was due to several intervals of lowered sea level, which allowed Asian ankylosaurids to cross into North America, resulting in the presence of two separate groups of ankylosaurid dinosaurs. This is because the lowering of sea levels exposed the Beringian land bridge, which these dinosaurs must have crossed. The authors believe that Akainacephalus once roamed the southern part of Laramidia, a land mass on the western coast of a shallow sea that split the continent of North America in two.
“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,” says Wiersma. “Such is exactly the case with Akainacephalus johnsoni; not only is this the first described and named Late Cretaceous ankylosaurid dinosaur from Utah, but this unique animal also strengthens the evidence that distinct northern and southern provincialism existed during the late Campanian stage in Laramidia, because to date, we don’t see this type of ankylosaurid dinosaurs in the fossil record of northern Laramidia.”
Ultimately, this discovery helps paint a clearer picture of the lives these dinosaurs led, and the evolutionary events that defined them. “It is extremely fascinating and important for the science of paleontology that we can read so much information from the fossil record, allowing us to better understand extinct organisms and the ecosystems they were a part of,” says Wiersma.
By Connor Ertz, Earth.com Staff Writer
Image Credit: Andrey Atuchin and the Denver Museum of Nature & Science