TIM EDWARDS - The beautifully preserved fossil of a dinosaur ‘baby’ has been unearthed in Utah. The skeleton is the smallest and most complete Parasaurolophus yet studied. It confirms for the first time that babies of this species began to grow their distinctive head crests extremely early in life.
The baby Parasaurolophus was probably less than a year old when it died in a river channel running through lush swamplands in southern Utah around 75 million years ago.
The remains - so well preserved that even the ruffles of the animal’s beak are visible - were discovered by high school student Kevin Terris who, with Andrew Farke of the Raymond M Alf Museum of Paleontology, was digging for fossils in the Kaiparowits Formation in a remote part of Grand Staircase-Escalante National Monument. The baby dino has been nicknamed 'Joe'.
Parasaurolophus is a duck-billed dinosaur. Its name - roughly translating as ‘near-crested lizard’ - refers to its distinctive crest, which protrudes backwards some way over the animal’s neck. A lot of duck-billed dinosaurs had these head crests, which were essentially complicated nasal passages covered in bone, but Parasaurolophus’ was one of the most impressive.
The purpose of Parasaurolophus’ crest has been the subject of much debate over the years. In the first half of the 20th century, when the dinosaur was thought to have been amphibious, various theories proposed the crest as a snorkel or some other underwater breathing aid.
A rival theory - that the trombone-like nasal passages allowed Parasaurolophus to produce a deep sound when it blew its nose - is widely accepted today and most scientists agree that the crest was used as a visual or aural display to potential mates or to help animals recognise other members of their species.
Parasaurolophus could grow to 9 metres in length. The baby Parasaurolophus, unveiled today in PeerJ by a team of scientists led by Farke, is 2 metres from nose to tail. It shows for the first time that these animals began growing their crests extremely early in life – much earlier than juveniles of other crested duck-bills such as Corythosaurus or Lambeosaurus, whose headgear began developing when they were half-grown.
But why would such a young animal need a crest if its primary purpose was to attract a mate?
Analysis of the baby’s leg bone shows that the animal was probably less than a year old and had been growing “horrendously quickly”, according to Farke.
“In fact,” he says, “it hadn’t stopped growing since the day it hatched. From what we know of other animals today, this means that it probably was not sexually mature.
“I speculate that our little guy started growing its crest so soon because the final product was so extreme - it took a long time to get where it needed to be.”
Based on other dinosaurs, this baby might have been one, two or even three years away from sexual maturity.
Of course, there is no reason why the crest of this baby Parasaurolophus could not have had a different purpose while it was growing up, for example to help adults keep in contact with their offspring.
Farke says that because the baby’s crest is much shorter than that of an adult, it would have made a much higher sound. In terms of stereo speakers, this baby’s crest was the tweeter to the parent’s woofer. Speaking purely speculatively, Farke says: “I would not be surprised if they used their calls to differentiate individuals, or at least figure out who else was in the area.
“Babies might listen to see if the adults were around, and vice versa. This could be pretty handy in a densely vegetated area.
“Whether that happened in a travelling herd, or breeding colony, or during parental care, would be a completely open question. But, I think it would be very fair to think that the calls helped animals know who was where.”
Images: Artist’s reconstruction of baby Parasaurolophus in its environment by Tyler Keillor; Adult and young Parasaurolophus heads (not to scale) by Lukas Panzarin; Silhouettes of adult and baby Parasaurolophus by Scott Hartman (baby dinosaur) and Matt Martyniuk (adult dinosaur); Artist’s reconstruction of baby Parasaurolophus by Lukas Panzarin