The newly described Probrachylophosaurus bergei, a member of the Brachylophosaurini clade of dinosaurs, has a small flat triangular bony crest extending over the skull and may represent the transition between a non-crested ancestor, such as Acristavus, and the larger crests of adult Brachylophosaurus, according to a study published November 11, 2015 in the open-access journal PLOS ONE by Elizabeth Freedman Fowler and John Horner from Montana State University, USA.
The superduck fossil was found in 1981 near the Montana-Canada border and was excavated in 2007 and 2008, the Missoulian said.
A nearby site also showed a fragmentary juvenile of the transitional Probrachylophosaurus, which suggests that successive generations of the Brachylophosaurus lineage grew larger crests by changing the timing or pace of crest development during growth into adulthood. "Now we've discovered a new species that have filled in that gap".
The scientific name of dinosaur species is Probrachylophosaurus bergei.
Their findings prove that the dinosaur remains they found manage to connect an ancestral form of the species Acristavus, which lived about 81 million years ago and had no crest to one of its descendants, Brachylophosaurus, which lived about 77.5 million years ago and boasted a larger crest.
Freedman Fowler affirmed that the Late Cretaceous of western North America was the only place on Earth where such profound paleo biological studies on dinosaurs could take place since the location combines the precise dating of rocks coupled with a remarkably high fossil record that has been collected over the years.
Speaking about the fossils, Fowler added, "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". It existed about 79.5 million years ago. The creature would have been about 30 feet long and weighed more than five tons.
Probrachylophosaurus' bony triangular nasal crest is somewhere in between what is seen in Acristavus and Brachylophosaurus.
Elizabeth Freedman Fowler said, "We knew what lived earlier and later", who is the curator of paleontology at the Great Plains Dinosaur Museum. The leg bones of the dinosaur sported growth rings, similar to a tree, allowing the scientists to discern that the super duck was around 14 years old.