An international group of researchers led by the University of Bristol has used computed tomography and biomechanical modeling to show how plant-eating dinosaurs fed 150 million years ago.

In the study, published today in the journal Naturwissenschaften, the group finds that Diplodocus – one of the largest dinosaurs ever discovered – had a skull adapted to strip leaves from tree branches.

The Diplodocus is a sauropod from the Jurassic Period and one of the longest animals to have lived on Earth, measuring over 30 m in length and weighing around 15 tones.

While known to be massive herbivores, there has been great debate about exactly how they ate such large quantities of plants. The aberrant Diplodocus, with its long snout and protruding peg-like teeth restricted to the very front of its mouth, has been the center of such controversy.

To solve the mystery, the researchers using data from a CT scan created a 3D model of a complete Diplodocus skull. This model was then biomechanically analyzed to test three feeding behaviors using finite element analysis (FEA).

FEA is widely used, from designing airplanes to orthopedic implants. It revealed the various stresses and strains acting on the Diplodocus’ skull during feeding to determine whether the skull or teeth would break under certain conditions.

“Sauropod dinosaurs, like Diplodocus, were so weird and different from living animals that there is no animal we can compare them with. This makes understanding their feeding ecology very difficult,” explained lead author Dr Mark Young of the University of Bristol and the Natural History Museum in London. “That’s why biomechanically modeling is so important to our understanding of long-extinct animals.”

“Using these techniques, borrowed from the worlds of engineering and medicine, we can start to examine the feeding behavior of this long-extinct animal in levels of detail which were simply impossible until recently,” said co-author Dr Paul Barrett of the Natural History Museum.

Numerous hypotheses of feeding behavior have been suggested for Diplodocus since its discovery over 130 years ago. These ranged from standard biting, combing leaves through peg-like teeth, ripping bark from trees similar to behavior in some living deer, and even plucking shellfish from rocks.

The team found that whilst bark-stripping was perhaps unsurprisingly too stressful for the teeth, combing and raking of leaves from branches was overall no more stressful to the skull bones and teeth than standard biting.

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Bibliographic information: Young MT et al. 2012. Cranial biomechanics of Diplodocus (Dinosauria, Sauropoda): testing hypotheses of feeding behaviour in an extinct megaherbivore. Naturwissenschaften, published online 12 July 2012; doi: 10.1007/s00114-012-0944-y