The first baby diplodocus skull ever found is helping scientists uncover how tiny babies that hatched from melon-sized eggs grew into the some of the largest animals that ever walked the Earth.
"You consider that you start your life coming out an egg the size of a cantaloupe. And when you die, you're a hundred feet long. That's quite a number of growth spurts you have to go through," said Cary Woodruff, lead author of a new study on the rare skull published Thursday in the journal Scientific Reports.
Diplodocuses belonged to a group of huge, long-necked, plant-eating dinosaurs that walked on four legs and are known as sauropods.
Andrew was unearthed in 2010 at a site in Montana called the Mother's Day Quarry by Glenn Storrs of the Cincinnati Museum Centre.
ABOUT "ANDREW'S SKULL"
Its skull is just 24 centimetres long — about the size of a pineapple fruit without the leaves. Researchers estimate Andrew was just two to four years old when it died 150 million years ago, during the Late Jurassic. There were about 15 other young diplodocuses in the herd, all six years old or less. It's not clear how they died.
Woodruff notes that diplodocuses don't seem to have cared for their young. Instead, the young animals would have moved in herds of animals similar in age, probably hiding in the forest along the coast of the nearby inland sea to avoid predators like Allosaurus. Despite its young age, Andrew was probably already six metres long — about the length of a cube van.
ANDREW'S TEETH
By studying the skull, Woodruff thinks he has some new clues about how diplodocuses grew so fast.
While adult diplodocuses have only 10 or 11 peg-like teeth at the front of a wide muzzle designed for grazing ferns in savannah-like landscapes, Andrew had a much narrower muzzle with 13 teeth that went all the way to the back of its jaws.
The ones at the back were spoon-shaped teeth designed to handle tougher material than just ferns.
GROWING UP FAST
"Andrew has to grow up really fast," he said, noting that diplodocuses reached full size in about 25 years. "To grow up really fast, it's got to eat a lot of food. With these different teeth, Andrew could basically pick and choose to eat any plant material around him."
He added that the narrower muzzle than that seen in adult animals also indicated that baby diplodocuses may have been pickier eaters than adults — but had more varied diet
It was funded by J.Horner and the Museum of the Rockies, with additional support from the Cincinnati Museum Center and the U.S. Bureau of Land Management.