Juvenile Diplodocus Skull

Description of a nearly complete juvenile skull of Diplodocus (Sauropoda: Diplodocoidea) from the Late Jurassic of North America. J.A. Whitlock, et al. JVP 30: 442–457.

Diplodocus carnegii adult and juvenile feeding,
Illo: 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.

"Diplodocus had an unusual skull," said Jeff Wilson, "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, has a pointed, rather than square, snout 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.