Dung Fossils Suggest Dinosaurs Ate Grass

Nicholas Bakalar
for National Geographic News
November 18, 2005

Ancient pieces of plant minerals have offered up the first evidence that dinosaurs ate grass, a new study says.

The proof was found in what might seem an unlikely location: fossilized dung left by titanosaurs.

The coprolites—the technical, and polite, term for dung fossils—were found in India and date to about 65 million years ago.

Evidence of ancient plants is often found in fossils that contain outlines of easily visible leaves and stems. Such fossils of grasses have been dated to about 55 million years ago but no older.

The plant evidence found in coprolites, however, is based on microscopic bits of minerals that form in plants. When plants are eaten or decay, the mineral bits are released and pass through an animal's digestive system.

Researchers were able to examine and date minerals from ancient grasses found in the fossilized dinosaur dung. The scientists describe the fossils in tomorrow's issue of the journal Science.

Their work "is the first unambiguous evidence that [grasses] originated and had already diversified during the Cretaceous," Dolores Piperno and Hans-Dieter Sues of the Smithsonian Institution's National Museum of Natural History wrote in a review accompanying the journal paper.

The Cretaceous period extends from 145.5 to 65.5 million years ago.

Grassy Dino Diets?

The fossils containing the plant minerals were found close to Pisdura in central India and date within the late Cretaceous.

Coprolites are very common in the area and are often found in rocks that have been worn down by weather. Based on their common association with titanosaur bones, many of the dung fossils probably come from the massive plant-eating reptiles.

The finding is the first indication that grasses evolved before the dinosaurs went extinct.

Continued on Next Page >>


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