A trumpet-blowing dinosaur had a head for music before its first birthday, research has shown.
Scientists made the discovery after the complete fossil skeleton of one of the creature's offspring was found by a high school student in southern Utah, US.
The tube-crested dinosaur Parasaurolophus, which lived 75 million years ago, was a duck-billed plant eater famous for its strange headgear.
A long hollow bony tube on top of the animal's skull was used both as a trumpet to blast out sound, and as a visual display, experts believe.
Researchers studying the six-foot-long baby dinosaur, nicknamed "Joe", found that at just one year old it already sported the beginnings of a crest.
The low bump would have given the creature an upper register voice, higher pitched than the calls of 25-foot long adults.
"Our baby Parasaurolophus is barely one-quarter of adult size, but it had already started growing its crest," said Dr Andrew Farke, from the Raymond M Alf Museum of Paleontology in California.
"This is surprising, because related dinosaurs didn't sprout their ornamentation until they were at least half-grown. Parasaurolophus had to get an early start in order to form its unique headgear."
He added: " If adult Parasaurolophus had 'woofers,' the babies had 'tweeters.' The short and small crest of baby 'Joe' shows that it may have had a much higher pitch to its call than did adults. Along with the visual differences, this might have helped animals living in the same area to figure out who was the big boss."
"Joe", the smallest and most complete Parasaurolophus fossil known, was discovered in 2009 by high school student Kevin Terris in Grand Staircase-Escalante National Monument, a vast conservation area in southern Utah.
He spotted what two professional palaeontologists had missed days earlier as they walked within several feet of the exposed fossil bones.
"At first I was interested in seeing what the initial piece of bone sticking out of the rock was," said Kevin. "When we exposed the skull, I was ecstatic."
Although partial skulls and skeletons of Parasaurolophus adults have been studied for more than 90 years, scientists previously knew little about how the dinosaur grew up.
The new fossil, described in the online journal PeerJ, revealed that like other dinosaurs, Parasoaurolophus increased in size rapidly after hatching from the egg. "Joe" grew to a quarter of adult size in less than a year.
Digital 3D scans of the dinosaur are freely available online via the link http://www.dinosaurjoe.com.