Dinosaur skull changed shape during growth

Mar 31, 2010
This is a Diplodocus carnegii adult and juvenile feeding. Credit: Reconstruction illustration: Mark A Klingler / Carnegie Museum of Natural History

The skull of a juvenile sauropod dinosaur, rediscovered in the collections of Pittsburgh's Carnegie Museum of Natural History, illustrates that some sauropod species went through drastic changes in skull shape during normal growth.

University of Michigan paleontologists John Whitlock and Jeffrey Wilson, along with Matthew Lamanna from the Carnegie Museum, describe their find in the March issue of the .

The fossil offers a rare chance to look at the early life history of Diplodocus, a 150 million-year-old sauropod from western North America.

"Adult skulls are rare, but juvenile skulls are even rarer," said Whitlock, a doctoral candidate in the U-M Museum of Paleontology. "What we do know about the skulls of sauropods like Diplodocus has been based entirely on adults so far."

"Diplodocus had an unusual skull," said Wilson, an assistant professor in the Department of Geological Sciences and an assistant curator at the U-M Museum of Paleontology. "Adults had long, square snouts, unlike the rounded or pointed snouts of other sauropods. Up until now, we assumed juveniles did too."

The small Diplodocus skull, however, suggests that major changes occurred in the skull throughout the animal's life.

"Although this skull is plainly that of a juvenile Diplodocus, in many ways it is quite different from those of the adults," Whitlock said. "Like those of most young animals, the eyes are proportionally larger, and the face is smaller. What was unexpected was the shape of the snout—it appears to have been quite pointed, rather than square like the adults. This gives us a whole new perspective on what these animals may have looked like at different points in their lives."

The researchers believe these changes in skull shape may have been tied to feeding behavior, with adults and juveniles eating different foods to avoid competition. Young Diplodocus, with their narrower snouts, may also have been choosier browsers, selecting high quality plant parts.

The discovery also highlights the importance of museum collections for paleontological research.

"Fossils like this are a great example of why natural history museums like ours put so much time and effort into caring for our collections, said Lamanna, an assistant curator of vertebrate paleontology at Carnegie Museum of Natural History. "This little Diplodocus skull was discovered in 1921, and more than 80 years passed before we recognized its significance. If the Carnegie Museum hadn't preserved it for all that time, the important insight it has provided into the growth and ecology of this dinosaur would have been lost."

The actual juvenile Diplodocus , as well as a fully restored, mounted skeleton of an adult, is on display in Carnegie Museum of Natural History's "Dinosaurs in Their Time" exhibition.

Explore further: New hadrosaur noses into spotlight

More information: Journal of Vertebrate Paleontology: www.vertpaleo.org/publications/index.cfm

Related Stories

Skull study sheds light on dinosaur diversity

Sep 15, 2005

With their long necks and tails, sauropod dinosaurs—famous as the Sinclair gasoline logo and Fred Flintstone's gravel pit tractor—are easy to recognize, in part because they all seem to look alike.

Pittsburgh U. gets fossil-rich land

Jan 25, 2006

A Wyoming cattle rancher has donated about 4,700 acres of his dinosaur-bone rich Wyoming ranch to the University of Pittsburgh.

T.rex's oldest ancestor identified

Nov 04, 2009

(PhysOrg.com) -- Remains of the oldest-known relative of T.rex have been identified, more than 100 years after being pulled out of a Gloucestershire reservoir, according to research published in the Zoological Jo ...

Scientists Discover New Species of Tyrannosaur

Feb 01, 2010

New Mexico is known for amazing local cuisine, Aztec ruins and the Los Alamos National Laboratory. In the January issue of the Journal of Vertebrate Paleontology, paleontologists Thomas Williamson of the Ne ...

Recommended for you

New hadrosaur noses into spotlight

Sep 19, 2014

Call it the Jimmy Durante of dinosaurs – a newly discovered hadrosaur with a truly distinctive nasal profile. The new dinosaur, named Rhinorex condrupus by paleontologists from North Carolina State Univer ...

Militants threaten ancient sites in Iraq, Syria

Sep 19, 2014

For more than 5,000 years, numerous civilizations have left their mark on upper Mesopotamia—from Assyrians and Akkadians to Babylonians and Romans. Their ancient, buried cities, palaces and temples packed ...

New branch added to European family tree

Sep 17, 2014

The setting: Europe, about 7,500 years ago. Agriculture was sweeping in from the Near East, bringing early farmers into contact with hunter-gatherers who had already been living in Europe for tens of thousands ...

User comments : 0