Newly Discovered Spiky-Headed Dino Hints at Dino Migrations

Friday, August 3, 2018

Illustration by Andrey Atuchin

“This one was a plant-eater and has kind of a wide grin. Not too fearsome, but I wouldn’t want to get whacked by that bony-tailed club,” says UC Berkeley grad Randall Irmis, discussing a spiky-headed dinosaur assembled before us in squat, bony glory at the Natural History Museum of Utah (NHMU), on the University of Utah’s campus. Curator of Paleontology at the museum, Irmis and others recently discovered this new dinosaur, an herbivore that roamed southern Utah 76 million years ago.

The dinosaur was pulled from a site in 2008 in southern Utah near Grand Staircase–Escalante National Monument, painstakingly processed for about four years, and is now dubbed Akainacephalus johnsoniAkainacephalus after its spiky head, and johnsoni after expert volunteer Randy Johnson, who did much of the prep work. The creature, which Irmis says “has never been described in the scientific literature before, and … hasn’t been found anywhere else,” is now written up in the science journal PeerJ. The creature was equipped with many spikes and was an ankylosaurid, a group known for formidable club tails and body armor.

As curator and associate professor in geology and geophysics at University of Utah, Irmis sees many parts of prehistoric creatures. But Akainacephalus is special. The museum has a large part of its skeleton (including nearly all of its skull), a large part of the vertebral column, limbs, ribs, and much of its armor. But more important, as the most complete ankylosaurid found in Utah so far, Akainacephalus johnsoni provides significant clues to how dinosaurs evolved and spread around the world.

Along with a dinosaur identified in New Mexico in 1999, Nodocephalosaurus kirtlandensis, Irmis says Akainacephalus is more like ankylosaurids found in Asia than other species from North America. This hints that ankylosaurids crossed a land bridge from Asia to North America at some point before 76 million years ago.

Why would that be the case? Well, plenty of anklyosaurids already have been found in Montana, Alberta, and other parts of North America. But as Irmis’s co-author Jelle Wiersma noticed in research at the museum, Akainacephalus has spiky bits on its head only found on the New Mexican specimen and on specimens in Asia—mainly in Mongolia and China. This means, Irmis explains, they all had a common ancestor that must have been found in Asia—and so ankylosaurs likely moved across a land bridge to North America at some point earlier than Akainacephalus’s lifetime.

The new dinosaur came from a site only partly excavated so far, that is chockfull of bones from that same time period. Though Irmis has participated in digs in New Mexico, Argentina, Ethiopia, and elsewhere, he notes Utah paleontology is exciting for a few reasons. For one thing, its finds are often recent. In Montana and Alberta, paleontological digs have been done for more than 100 years. But in the area of Utah where this dinosaur was found, the paleontological research has taken place for around the last 30 years. “That area of Utah is one of the last pieces of terrain in the lower 48 states to be mapped, and less accessible than some places,” Irmis says.

Getting into those less-accessible places sometimes involves backpacking with dig tools then transporting any finds weighing less than 300 pounds by hospital carrier. But the relatively undisturbed sites help scientists reconstruct earlier ecosystems, “from plants to insects to dinosaurs, find by find,” says Irmis.

Those scientists are trying to build clues to life in a dramatically different climate, Irmis notes. In the age of dinosaurs, 230 to 66 million years ago, there were no polar ice caps, temperatures were very high, and carbon dioxide levels were much higher. As Earth’s current temperatures warm, Irmis says, scientists can use information from that age as an analog for what might happen in the future.

For instance, back when Akainacephalus chewed greens in marshes, Utah was farther north than today, but had an environment more like today’s southern Louisiana. Similar dinosaurs dwelled in Alaska’s northern slopes and southern Utah, as research at UC Berkeley determined. “With such a different world and climate, did ecosystems function differently than they do today?” asks Irmis.

That’s for paleontologists and others to find out. Offered his current position at NHMU while still finishing his doctoral degree in Berkeley (he received his Ph.D. in 2008), Irmis says accepting was a no-brainer: “Utah has one of the best fossil records in the U.S., and after my time at Berkeley with great fieldwork and a world-class museum collection of paleontology, I was especially enthusiastic about being in a place where I could work on faculty and as a curator at a museum. I lucked out.”

Some people ask him if teaching graduate classes and curating is too much, but he says it’s an ideal combination. ”You have grad students and you can take them on digs, but you also have museums where these data are reposited, and you can communicate directly with the public about those finds. Nothing’s more immediate than interacting with people who’ve come to a museum to see the paleontology and other natural history research being done.”