The fossil of a new species of duckbilled dinosaur, which paleontologists have dubbed "Superduck," sheds light on how such dinosaurs evolved and got their distinctive skull crest, researchers say.
The flashy head crest of Probrachylophosaurus bergei, found in Montana, may represent a missing link between other already well-known dinosaur species, they point out.
Paleontologists say they have linked the new species to an earlier dinosaur relative that had no crest and to another later species that sported a large, distinctive crest.
P. bergei falls somewhere in the middle between non-crested Acristavus and Brachylophosaurus with its large crest, says Elizabeth Freedman Fowler of the Museum of the Rockies and Montana State University.
The crest of the "Superduck" dinosaur "would have only poked up a little bit on the top of the head, above the eyes," she explained.
"It is a perfect example of evolution within a single lineage of dinosaurs over millions of years," she said.
Dubbed "Superduck" because of its size, P. bergei could grow to about 30 feet in length and be as heavy as 5 tons. It lumbered over terrain about 79 million years ago, the researchers report in the journal PLOS ONE.
An examination of the fossil leg bones found in the Judith River Formation in north-central Montana shows this "Superduck" was 14 years old when it died, not quite fully grown.
Duckbilled dinosaurs, named for beaks that resemble a duck's bill, were common on Earth in the later parts of the Cretaceous Period.
The crests of duckbilled species would have been either too small or too large and fragile to be used as a weapon during fights, the researchers suggest.
Rather, it is likely the head crests — possessed by both males and females — allowed individuals to recognize others of their species and would have been a sign that an animal was sexually mature, the researchers say.
"On a crowded floodplain, you want to make sure you stay with the right (dinosaur) herd," Freedman Fowler says. "The crests may have also helped them attract mates."
Most of the skull, pelvis, hind legs, vertebrae and ribs of the "Superduck" have been excavated, which gives a good impression of the overall configuration of the creature and of its evolving crest.
"Because the fossil record is very spotty and we only get glimpses of evolutionary trends, it is always exciting to find evidence of transitional species," said Freeman Fowler's MSU colleague Jack Horner.
