Even flossing wouldn’t have helped
By Sid Perkins
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
dinosaurs.
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.
