The rhino-like Triceratops, Greek for "three-horned face," didn't always embody its name in way we picture it doing. By comparing 50 skulls collected over a 15-year period from the Hell Creek Formation in Montana, paleontologists have learned that it took between 1 million and 2 million years for the large nasal horn it is famous for today to fully develop, while what started as a long beak shortened over that same time period, the scientists report in the Proceedings of the National Academy of Sciences. Though they've established the evolution, the study's lead author tells USA Today that "it's difficult to say what drove the change."
The first Triceratops skeleton was found in 1887, reports CNN, and was at first thought to be that of a (presumably very large) buffalo. Two years later, a Yale scientist named it Triceratops for its impressive three-horned skull, which the scientists had previously learned changes subtly in shape over the course of a single lifetime as well. A half-million years before their extinction, they roamed the Earth in great numbers, reports UPI, which points out that our understanding of the Triceratops has been greatly boosted by the fact that so many fossils of the creature can be found in the Hell Creek Formation. "We went out and looked at where the fossils came from in context of the rock formation," the lead author explains. "The ones found low in the formation look different from the ones found high up." (Click to read about how one relative of Triceratops had wings on its head.)