Oklahoma Paleontologists Help Discover Oldest Horned Dinosaur in North America

Read the findings in PLOS ONE.

Paleontologist Scott Madsen, a member of Cifelli's field team, unearthed the skull of Aquilops in 1997 from the Cloverly Formation of southern Montana.

Dr. Cifelli told News On 6 part of the reason it took so long to publicize the find was the state of the fossil. He said the skull was encased in stone like concrete, so a specialist used a carbide-tipped needle to remove one or two grains of sand at a time.

"I was stunned, astonished," Dr. Cifelli said about realizing what they had found.

Paleontologists have struggled to reconstruct the evolutionary history of the Ceratopsia, popularly known as “horned dinosaurs,” in North America because not many fossils exist. 

"A few teeth from Maryland, part of a skeleton from Idaho," Dr. Cifelli said. "This was the first unambiguous one. Absolutely diagnostic."

The scientific name of the new ceratopsian is Aquilops americanus or “American eagle face,” which is a hybrid from two classical languages: “Aquila,” Latin, meaning eagle; and “ops,” Greek, meaning face. 

Dr. Cifelli said the team found the skull while spending somewhere between 1,000 to 2,000 man hours at the site in Montana.

Aquilops is recognized as a ceratopsian by its spike-like cheekbones and distinct upper beak bone, which Farke characterizes as a “ceratopsian membership card.”  It differs from typical forms, such as Triceratops, because it lacks facial horns and a long frill extending over the neck, according to the release.

"This guy," Dr. Cifelli said, "it sticks out sort of like a bike helmet or beret turned backward."

The new species dates to approximately 108 million years ago, 20 million years older than any other named ceratopsian species from North America.

The paleontologists say Aquilops was roughly the size of a small cat and weighed about three pounds. That's another key difference from its larger  relatives. 

They say the fossil record suggests horned dinosaurs arose in Asia and spread to North America by about 108 million years ago, the age of Aquilops. 

Lead author of the study is Andrew Farke, a paleontologist from the Raymond M. Alf Museum of Paleontology in Claremont, California, and a specialist on horned dinosaurs.

“Life on land underwent profound changes during the latter part of the age of dinosaurs. This new find supports the view that migration events were fundamental in driving those changes,” said Farke. “Aquilops represents just one of many groups that made the trek from Asia to North America.”

The discovery provides new information on the evolutionary history and migratory patterns of one of the most successful of all dinosaur groups.

“It would appear,” said Cifelli, “that immigration to North America is not limited to historic times, but is a pervasive theme through Earth history, driving change to both past and present communities.”

The skull of Aquilops will be stored in the vertebrate paleontology collection at the Sam Noble Oklahoma Museum of Natural History in Norman, Oklahoma. 

It will be the nucleus for development of an in-house virtual exhibit to go on display in 2015 in the museum's Hall of Ancient Life alongside the museum's Pentaceratops, which holds the Guinness World Record for being the largest dinosaur skull ever found.

Dr. Cifelli has experience with dramatic fossil finds. A few years ago he identified the neck bone of a sauropod found in Atoka County, Oklahoma. The bone was almost five feet long and belonged to a dinosaur called sauroposeidon. The whole dinosaur was more than 100-feet long, with its neck alone stretching 39 feet. 

Sauroposeidon means "earthquake god lizard," which Dr. Cifelli says it earned because of what it must have sounded like when it walked.