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

By Helen Thompson

January 12, 2016 at 12:00 pm

“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.