Imagine if the shape of your head changed with the foods that you ate. That's what a team of paleontologists now thinks happened to the long-necked sauropod dinosaur, Diplodocus, which also was one of the least intelligent dinosaurs. Its head might have been interesting, in terms of shape, but previous studies suggest there wasn't a lot of brain power in it. But, as for all animals, it evolved what it needed for survival.
Diplodocus was a huge, hefty dinosaur that lived towards the end of the Jurassic Period around 150 million years ago in North America.
Carnegie Museum of Natural History
Assistant Curator of Vertebrate Paleontology Matthew Lamanna and colleagues made the determination after analyzing the skull of a juvenile Diplodocus that was recently rediscovered in the museum's collections. The researchers were surprised that this head was so different from that of adults of the same species.
"Diplodocus had an unusual skull," said Jeffrey Wilson, a co-author of the paper, published in the current issue of the Journal of Vertebrate Paleontology. "Adults had long, square snouts, unlike the rounded or pointed snouts of other sauropods. Up until now, we assumed juveniles did too."
John Whitlock of the University of Michigan, who also worked on the study, explained that while the "rediscovered" juvenile head is definitely a Diplodocus, the individual must have changed a lot as it grew up.
"Like those of most young animals, the eyes are proportionately larger, and the face is smaller," Whitlock said. "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 scientists think the changes occurred due to diet. Mammals with narrow snouts use them to choose specific, relatively nutritious plant parts, while blunt-snouted mammals tend to indiscriminately “mow down” low-growing plants. The young dinosaurs must have been pickier eaters, browsing more selectively than their adult relatives did. The dinosaurs probably all ate different foods to avoid competing with each other.
In addition to the skull determinations, Lamanna believes the
discovery 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," he said. "This little Diplodocus skull was discovered in 1921 and briefly mentioned in a scientific paper in 1924. More than 80 more years passed before my collaborators and I recognized its significance. If we at the Carnegie Museum hadn’t preserved this skull for all that time, the important insight that it’s provided into the growth and ecology of this dinosaur would have been lost."
You can see the juvenile Diplodocus skull, as well as a fully restored mounted skeleton of this same species in the Carnegie Museum of Natural History's "Dinosaurs in Their Time" exhibition.
Tags: Dinosaurs, Extinct Animals, Middle and Late Jurassic Dinosaurs, Paleontology, Prehistoric Animals,
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