With a signature frilled skull and beaked nose, Ceratopsia are among the most recognizable and best-known dinosaurs in history. But where did these “horned dinosaurs” come from? Because of a limited fossil record, paleontologists have struggled for decades to reconstruct the early evolutionary history of Ceratopsia in North America. Now, thanks to a skull no larger than a lemon, researchers are closer than ever before to understanding the 108 million-year-old mystery.
The skull, named Aquilops americanus (“American eagle face”), represents a 3-pound relative of Triceratops, which weighed up to 4,000 times more. A ‘no frills’ ceratopsian, the new species Aquilops also lacks the trademark head shield and facial horns of its distant cousins. Roughly the size of a small cat, it is estimated to have been two feet long—another point of contrast with its truck-sized relatives.
A team of paleontologists led by Rich Cifelli, Sam Noble Museum, unearthed the ceratopsian during a 1997 expedition funded by the National Geographic Society’s Committee for Research and Exploration. Aquilops is now considered the oldest member of the horned dinosaur lineage named from North America and provides important new information on vertebrate history during the latter part of the age of dinosaurs.
The expedition team’s findings were published in the Dec. 10 issue of the scientific journal PLOS ONE. 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.
The fossil record suggests that horned dinosaurs arose in Asia and dispersed to North America near the present-day Bering Strait by about 108 million years ago, the age of Aquilops. Surprisingly, however, the study by Farke and colleagues places Aquilops near the base of the ceratopsian family tree, far removed from horn-bearing Triceratops and other North American relatives. Relationships among these upper branches of the genealogical tree suggest that two or more immigration events happened later in the Cretaceous.
The skull of Aquilops belongs to the vertebrate paleontology collection at the Sam Noble Oklahoma Museum of Natural History in Norman, Oklahoma. It will be featured in a new exhibit to go 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.
