Triceratops and other horned dinosaurs once thrived in North America, but paleontologists have long wondered how the group originally made it to the continent. Now, an analysis of a small, crow-size horned dinosaur — the oldest horned dinosaur ever found in North America — suggests these dinos migrated from Asia to North America between 113 million and 105 million years ago.
Paleontologists originally uncovered the skull of the horned dinosaur in Montana in 1997 — an exciting find, given that until then, scientists had only found a handful of teeth, bones and a tail of early horned North American dinosaurs known as neoceratopsians. The new species, called Aquilops americanus, lived during the Early Cretaceous, about 107 million years ago.
"It's the first complete specimen of a horned dinosaur found in North America from that time," said the study's lead researcher, Andrew Farke, a paleontologist at the Raymond M. Alf Museum of Paleontology in Claremont, California. "And it's even more exciting because it's not at all closely related to later horned dinosaurs from North America." [See photos of the horned dinosaur fossil]
Instead, Aquilops, which means "eagle face" in Latin, is most closely related to animals from Asia, including the dinosaurs Archaeoceratops oshimai and Leptoceratops gracilis.
"In most features, it's virtually identical to them," Farke told Live Science. "And that's cool because it adds support for this idea that, around 110 million years ago or so, there was a big influx of animals from Asia into North America."
The next known horned dinosaur in North America didn't live until about 20 million years after Aquilops, and Triceratops lived about 40 million years later, the researchers said.
The findings were published Wednesday (Dec. 10) in the journal PLOS ONE.