A new fossil find may help demystify one of the strangest dinosaurs known to have roamed the ancient West — a duck-billed plant-eater with an unusual, hollow, tube-like crest sprouting from the top of its skull.

The fossil, discovered in southern Utah, contains the most complete skeleton ever found of Parasaurolophus, which browsed the intermountain West some 75 million years ago.

The remains were found in 2009 in Grand Staircase-Escalante National Monument by a curious high school student. Paleontologists soon discovered that the exposed bones spotted by the boy were part of a nearly complete baby Parasaurolophus, the youngest ever found. [Read about an unusual new species of ceratops discovered in Grand Staircase earlier this year: “New Bull-Horned, Big-Nosed Ceratops Unearthed in Utah“]

Aside from the rarity of the find — only a handful of partial Parasaurolophus specimens have been found in North America — the animal’s tender age at the time of its death is providing new insights into how the dinosaur, and its unique features, developed.

In particular, scientists have been surprised to find that the baby had already sprouted the “strange headgear” that was its species’ signature, even though it was likely less than a year old.

“Our baby Parasaurolophus is barely one-quarter of adult size, but it had already started growing its crest,” said Andrew Farke, paleontologist with the Raymond M. Alf Museum in Claremont, Calif., in a statement.

“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.”

The young dino was about 1.8 meters long when it died, bigger than most of us, but just a fraction of a mature Parasaurolophus’ 7.5 meters or more.

To determine the juvenile’s exact age, the team studied a cross-section of its leg bone, said Sarah Werning of Stony Brook University.

“Dinosaurs have yearly growth rings in their bone tissue, like trees,” Werning said in the statement. “But we didn’t see even one ring. That means it grew to a quarter of adult size in less than a year.”

These are particularly useful data points for scientists who have been trying to solve one of the more compelling puzzles posed by Parasaurolophus — what purpose could its head ornament have served?

When the genus was first discovered, from a fossilized cranium unearthed in Canada in the 1920s, some scientists thought that Parasaurolophus lived in the water and the crest functioned as a kind of primordial snorkel.

Later, others theorized that it was more like a prehensile nose, similar to an elephant’s trunk — until it became clear that there was no opening at the end, and that the tube was in fact covered by bone or other tissue.

Today, most experts believe the crest was a distinguishing feature that species used to identify each other, and may have served as a sexual display.

But many also speculate that, since the animal’s nasal cavities ran the length of its crest, the tube could also have been used to make sounds.

The scientists studying the Utah baby hew to this theory, so they scanned the specimen’s skull to size up its potential ability to “trumpet.” Their conclusion:

“If adult Parasaurolophus had ‘woofers,’ the babies had ‘tweeters,'” said Farke.

“The short and small crest of [the] baby … 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.”

Other scientists, as well as the public, will be able to keep plumbing the mysteries of Parasaurolophus with the help of this new discovery: The team and the Alf Museum have posted three-dimensional scans of the specimen online for anyone to view.

“This will allow scientists and the public alike unparalleled access to this fossil,” museum officials said.

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A.A. Farke, D. J. Chok, A. Herrero, B. Scolieri, & S. Werning (2013). Ontogeny in the tube-crested dinosaur Parasaurolophus (Hadrosauridae) and heterochrony in hadrosaurids PeerJ : http://dx.doi.org/10.7717/peerj.182