Dinosaur mummy's fleshy head crest
A mummified dinosaur provides the first evidence the scaly animals had fleshy head ornaments, scientists say.
The preserved remains of the duck-billed dinosaur Edmontosauraus regalis were discovered in Alberta, Canada.
Analysis revealed the previously unknown feature which experts compared to a rooster's comb.
They suggest the ornaments were used to attract mates in the same way modern birds use bright appendages.
The findings are published in Current Biology.
"This is the first evidence of an entirely soft-tissue crest for any dinosaur," said lead author Dr Phil Bell from the University of New England, Australia.
"Bony crests are well known but skin rarely fossilises and even when it does, it is almost never found on the skull."
The specimen was discovered by co-author and geologist Frederico Fanti from the University of Bologna, Italy.
"While we were using a rock saw to cut the block down in the field to make it easier to transport, we discovered skin impressions quite by accident but it wasn't until we got the block back to the lab that we realised just how extensive the skin was," explained Dr Bell.
E. regalis is a member of the Hadrosaurid family - also known as the duck-billed dinosaurs.
They were the most common dinosaurs in North America between 75 and 65 million years ago and used their long bills to graze on vegetation.
Soft tissue is often lost in the process of fossilisation but preserved tissues from hadrosaurs have been found in recent years.
Experts suggest that when an animal was instantly buried in certain sediments, decay was slowed down through a lack of oxygen and soft tissues were mineralised.
This process allows microscopic details and even original organic compounds to be preserved so the remains are sometimes referred to as 'dinosaur mummies'.
Other hadrosaurs are known to have had hollow bone structures on their heads, whereas pterosaurs had smooth crests made of keratin - the hard fibrous proteins responsible for beaks, horns and fingernails.
But the scaly, fleshy structure found in E. regalis "raises the thought-provoking possibility of similar crests among other dinosaurs," according to Dr Bell.
The research team's illustrated reconstruction, that suggests the crest was brightly coloured, is based on evidence of similar appendages seen in the modern world.
"Based on comparisons with living birds, crests like that in Edmontosaurus were probably used to attract mates," said Dr Bell.
"Often, the largest and most brightly coloured crest gets the girl and in the case of herding animals, it probably identified who was the head of the group."