Like today's crested roosters, who rise at a day's first light, one crested, duck-billed dinosaur is shedding new light on the earth's prehistoric evolution.

Long-held scientific assumptions said the duck-billed Edmontosaurus regalis had a plain head, no elaborate neck frill or horns or spikes, none of the fancy head ornaments sported by many others in the dino world.

Researchers have announced, with notable excitement, that the Edmontosaurus regalis in fact had on the top of its head a fleshy adornment that bobbled, unique in that era.

The reality-shifting find is described in the Dec. 12 edition of the journal Current Biology's Cell Press.

Duck-billed dinosaurs were gentle giants are believed to have been the most common dinosaurs in North America between 75 and 65 million years ago, individually measuring about 30 feet long and filled the same ecological role that plant-eating kangaroos or deer play today.

But, "until now, there has been no evidence for bizarre soft-tissue display structures among dinosaurs," said researcher Phil Bell from Australia's University of New England. The new data "dramatically alter our perception of the appearance and behavior of this well-known dinosaur and allow us to comment on the evolution of head crests in this group ... it also raises the thought-provoking possibility of similar crests among other dinosaurs."

The Edmontosaurus regalis specimen in question was found in deposits in west-central Alberta, Canada. Bell says he and colleague Federico Fanti, of the University of Bologna in Italy, knew they had unearthed something special when they found skin impressions on parts of the dinosaur's mummified body.

When Bell inserted a chisel through the top of the dino's crest, he was confident he'd found something extraordinary.

"An elephant's trunk or a rooster's crest might never fossilize because there's no bone in them," Bell said. "This is equivalent to discovering for the first time that elephants had trunks. We have lots of skulls of Edmontosaurus, but there are no clues on them that suggest they might have had a big fleshy crest. There's no reason that other strange fleshy structures couldn't have been present on a whole range of other dinosaurs, including T. rex or Triceratops."

The curved crest apparently grew to about 8 inches high and about a foot in length, making it look like an under-sized bowler hat, atop of a creature that weighed as much as a bulldozer.  

Other dinos known to have crests made of bone probably used their headgear for sound production. In the case of the Edmontosaurus, which was a notably social creature that lived at least part of its life in large herds, the crest more probably served as a signal to its relatives, allies or potential love interests.

"We might imagine a pair of male Edmontosaurus sizing each other up, bellowing, and showing off their head gear to see who was the dominant male and who was in charge of the herd," said Bell.