|Reconstruction of duckbilled dinosaur, Edmontosaurus regalis.|
Credit: Bell, Fanti, Currie, Arbour, Current Biology
The comb is made of soft tissue. Soft tissues rarely fossilize because they do not contain any bone in them. Because of this, these features are unknown to exist in many extinct species such as dinosaurs. Scientists are not sure what the purpose of the appendage is, but they theorize it is for social signaling or sexual selection.
Edmontosaurus Regalis is part of a genus of dinosaurs called hadrosaurids or duck-billed dinosaurs. Edmontosaurus lived during the Cretaceous Period 73 million years ago and are about 40 feet long and 13 feet high at the hips. These dinosaurs weigh around 4 tons. One prominent feature of the dinosaur is that its mouth has around 1300 teeth that is constantly replaced just like a shark.
The discovery of the comb suggests that it is possible that other species of dinosaurs may have similar features.
The Haed Crest of Edmontosaurus Regalis
A rare, mummified specimen of the duck-billed dinosaur Edmontosaurus regalis described in the Cell Press journal Current Biology on December 12 shows for the first time that those dinosaurs' heads were adorned with a fleshy comb, most similar to the roosters' red crest.
The most common dinosaurs in North America between 75 and 65 million years ago, duck-billed dinosaurs were gentle giants, about 12 meters long, and filled the same ecological role that kangaroos or deer play today. But no one had suspected that they—or other dinosaurs, for that matter—had fleshy structures on the tops of their heads.
"Until now, there has been no evidence for bizarre soft-tissue display structures among dinosaurs; these findings 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," says Phil Bell from Australia's University of New England. "It also raises the thought-provoking possibility of similar crests among other dinosaurs."
Video: Edmontosaurus Simulation Before 'Rooster's Comb' Discovery
The dinosaur specimen in question was found in deposits west of the city of Grande Prairie in west-central Alberta, Canada. Bell, along with Federico Fanti from the University of Bologna, Italy, knew they had something special when they found skin impressions on parts of the mummified body. But it wasn't until Bell put a chisel through the top of the crest that he realized they really had something incredible.
"An elephant's trunk or a rooster's crest might never fossilize because there's no bone in them," Bell explains. "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."
Of course, it's hard to tell what that cocks comb might have done for the duck-billed dinosaurs. In roosters and some other birds, bright red crests are a way to get the girls. "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 is in charge of the herd," Bell says.
We may never know exactly, but the new study is a useful reminder of just how bizarre and amazing dinosaurs really were, the researchers say. There is much left to discover.
A mummified duck-billed dinosaur with a soft-tissue cock's comb
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