Samplings: June 2008

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Araucaria araucana twigs with young pollen cones in spring. The spiky leaves of this ancient conifer, commonly known as the monkey puzzle tree, may have provided some protection from grazing dinosaurs. 

Georg Oleschinski

In the dinosaurs’ day, the plant kingdom was ruled by primitive greenery that biologists have presumed to be only marginally digestible, and thus a poor energy source for herbivores. How could such scanty fare support colossal vegetarian dinosaurs, such as sauropods, which weighed up to seventy tons and were the largest creatures ever to walk the Earth? Sauropods would have needed to eat such massive quantities of vegetation that it would have been difficult for any ecosystem to support a sustainable population of them. Now Jürgen Hummel at the University of Bonn in Germany and several colleagues have shown that the ancient veggie diet was more nourishing than previously thought. Using test tubes full of digestive microbes from sheep to simulate sauropod stomachs, the team tested the digestibility and energy content of eighty-six plant species—the nearest living relatives of ones the dinos probably ate. Many of the prehistoric plants, particularly horsetails, ginkgos, certain conifers, and ferns, yielded energy sufficient to support the enormous sauropods. Cycads, tree ferns, and a subset of conifers, on the other hand, would have made poor meals. That probably didn’t put the dinos off, though: they couldn’t afford to be picky eaters with such bulky bodies to sustain. Hummel says a balanced mix of greens was the foundation of their supersize success—not such bad advice for people, either. (Proceedings of the Royal Society B)