Fossils provide link in dino crest evolution

Skeletal remains show how duck-billed dinosaurs evolved


SUPERDUCK  Estimates based on its skull (left) and skeleton put P. bergei at about 9 meters long. Its descendants, B. canadensis (right), didn’t have much bigger skulls, but their crests grew larger.

E.F. Fowler

“Superducks” once roamed the Montana landscape. Montana State University paleontologists Elizabeth Freedman Fowler and Jack Horner described the large duck-billed dinosaurs with strangely tiny nasal crests November 11 in PLOS ONE.

Unearthed in 2007, Probrachylophosaurus bergei’s most notable feature is a small, triangular crest that runs from the snout up to the forehead. Its bones resemble a hybrid of earlier noncrested dinosaurs with flat snouts, Acristavus, and their crested descendants, Brachylophosaurus, which sported a more pronounced profile.

Fowler and Horner say the new species lived between 79.8 million and 79.5 million years ago — between the heydays of the other two groups. In fact, the researchers argue, P. bergei is a missing link between duck-billed dinosaurs with and without crests.

“We’re seeing a trend over millions of years, in many different lineages, of crests evolving and getting larger,” Fowler says. Even the skull of a juvenile P. bergei showed signs of a wee crest. Fowler suspects that crests may have served as a way to recognize members of the same species or potential mates.

Helen Thompson is the multimedia editor. She has undergraduate degrees in biology and English from Trinity University and a master’s degree in science writing from Johns Hopkins University.

More Stories from Science News on Paleontology