Large, Plant-Eating Dinosaurs Had Specialized Diets to Survive

Millions of years ago, dinosaurs roamed the planet. Many of them ate plants, consuming hundreds of pounds of material per day in order to feed their massive bulk. Yet with so many species of large, plant-eating dinosaurs, how did they all successfully co-exist? Researchers may now have the answer, thanks to a new study.

In order to find out exactly how different species of dinosaurs managed to survive in the same area, researchers measured and analyzed the characteristics of nearly 100 dinosaur skulls recovered from the Dinosaur Park Formation in Canada. This area, which is estimated to be between 76.5 and 75 million years old, is known for its rich concentration of dinosaur remains. In fact, it's yielded nearly 20 species of megaherbivores from the Late Cretaceous period. Six species of these megaherbivores would have coexisted at any one time, which means that they would have had to compete for resources.

"Today's megaherbivore communities are not nearly as diverse as those from the Late Cretaceous of Alberta, and most other fossil communities also pale by comparison," said Jordan Mallon, a post-doctoral fellow at the Canadian Museum of Nature, in a news release. "So the question is: how does an environment support so many of these large herbivores at once?"

The researchers ended up testing two theories. One is that the availability of food was not a limiting factor in species survival; this could possibly due to a super-abundance of resources or relatively slow metabolisms in the dinosaurs. The other theory is that the available food resources were limiting and that niche partitioning came into play; in other words, there weren't enough plants, so species specialized in different types of vegetation.

While examining the skulls, the researchers found striking yet significant differences within three major groups--the ankylosaurs, hadrosaurs and ceratopsids. These differences were probably related to feeding, and seemed to point to the fact that the dinosaurs specialized in different plant material types. For example, ankylosaurs probably specialized in eating ferns since they stood low to the ground and had wide beaks that would have allowed them to feed efficiently on abundant, low-nutrient plants. Hadrosaurs, in contrast, were far taller and would have fed on anything within reach.

"We found differences that were previously expected but never demonstrated," said Mallon. "This tells us that niche partitioning was a viable strategy for the coexistence of these animals. The study provides further evidence to explain why dinosaurs were one of the most successful groups of animals to live on this planet."

The findings are published in the journal PLOS One.