While researchers from the Museum of the Rockies were excavating at Montana’s Judith River Formation, they discovered a new species of duck-billed dinosaur. The new discovery showcases an evolutionary transition from an earlier duck-billed species to that group’s descendants, according to a paper published in the journal PLOS ONE.
Authors of the study, professor Elizabeth Freedman Fowler and paleontologist Jack Horner, curator of paleontology at MSU’s Museum of the Rockies, believe “the new species of duck-billed dinosaur neatly fills a gap that had existed between an ancestral form with no crest and a descendant with a larger crest, providing key insight into the evolution of elaborate display structures in these gigantic extinct herbivores,” according to a press release.
“It is really gratifying to see Dr. Freedman Fowler’s work, which is essentially her dissertation, published in PLOS ONE,” Horner said. “It is confirmation that she is an excellent paleontologist, helping further cement MSU’s reputation for offering graduate students a chance to be part of something extraordinary.”
“The first bones we uncovered were the pelvis and parts of the legs, which were so large it led to the site being given the nickname ‘Superduck,'” Fowler said.
In the study, the new species has been named Probrachylophosaurus bergei (pronounced pro-BRAH-KEE-loh-foh-saw-rus), with the authors suggesting it is the link between Acristavus, which roamed Earth around 81 million years ago, and the Brachylophosaurus, which roamed Earth about 77.5 million years ago.
‘It is a perfect example of evolution within a single lineage of dinosaurs over millions of years.’
Fowler explained: “The crest of Probrachylophosaurus is small and triangular, and would have only poked up a little bit on the top of the head, above the eyes.”
“We cut open one of its leg bones, the tibia, and counted the growth rings,” Fowler explained. “Superduck was 14 years old when it died, and it was close to full size, but it would have grown a bit larger if it had lived longer. It was about 29 feet long and would have weighed about 5 tons.”
According to CS Monitor, Probrachylophosaurus and its cousins were hadrosaurs — a family of duckbilled, herbivorous dinosaurs known for their strange and highly variable crests. These crests would grow — subtly in some species, extravagantly in others — as the individual aged into adulthood. Some modern birds, like cassowaries and hornbills, possess similar features.
“We think that the crests of dinosaurs were visual signals so that they could recognize members of their own species, and also tell whether the animal was mature or not,” says Fowler. “This supports other evidence of most dinosaurs being very social animals, similar to most modern birds.”
The scientists retrieved most of the skull, pelvis, hind legs, vertebrae, and ribs near the town of Rudyard. They had also unearthed the remains of a second Probrachylophosaurus, more of an adolescent in age, but it was not as complete as the first.
“Even though paleontologists have been collecting dinosaurs in Montana for over one hundred years, we are still making exciting new discoveries every single year,” Fowler says. “You can’t find anything new if you don’t go out and dig for it.”