Even flossing wouldn’t have helped

From Bozeman, Mont., at the 61st annual meeting of the Society for Vertebrate Paleontology

Small particles trapped in minuscule cracks or pits in the fossilized teeth of

some plant-eating dinosaurs could give scientists a way to identify what types of

greenery the ancient herbivores munched.

Many types of plants produce phytoliths–literally, plant stones–in their stems and

leaves by converting the silica dissolved in groundwater into a crystalline form

similar to opals. These tiny parcels of grit come in a wide variety of shapes and

sizes, and they have a microscopic structure different from that in silica

crystals formed by geologic processes, says David A. Krauss, a paleobiologist at

Boston College.

Because they’re harder than tooth enamel, phytoliths scratch tooth surfaces and

can become embedded in small cracks there. Krauss examined a collection of teeth

from hadrosaurs and ceratopsians–two different groups of plant-eating

dinosaurs–unearthed in Dinosaur Provincial Park in Alberta, Canada. He found that

about 25 percent of these teeth had phytoliths trapped in the chewing surfaces.

Different types of plants produce phytoliths that look alike, but some groups of

species generate distinct crystal forms. Krauss analyzed the phytoliths produced

by living relatives of the ancient plants found in the fossil layers holding the


The sizes and shapes of crystals from the fossil teeth suggest that the

ceratopsian dinosaurs, relatives of Triceratops, may have eaten a high proportion

of tough-leafed cycads, whereas the hadrosaurs, or duck-billed dinosaurs, probably

favored ferns.

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