Dinosaurs teeth reveal what they ate

Ximena: How do paleontologists know if a dinosaur was a carnivore or herbivore, if they were only able to study their bones? Because dinosaurs teeth reveal what they ate.

EarthSky asked Paul Barrett, a paleontologist who studies dinosaur diets at the Natural History Museum in London. He explained how scientists figure out what dinosaurs ate by looking at their fossils.

Paul Barrett: First of all, we would have a look at the teeth, and the general structure of the head of the animal, and then compare the things we saw there with living animals whose diets we know something about.

Barrett said that just like the animals around us today, dinosaurs had teeth adapted to what they ate. So carnivores, or meat-eaters, had sharp, serrated teeth, like the edge of a knife. Herbivores, or plant-eaters, had teeth that were designed for crushing and grinding plants, much like a cow’s. But, Barrett said, certain dinosaurs had no teeth, which makes their diet a nearly unsolvable mystery to paleontologists.

Paul Barrett: Some of the most interesting dinosaurs are the ones with no teeth. Their skulls don’t have any teeth in them at all. Not because their teeth just dropped out, but because they never had teeth in the first place. Because they lack this big clue, the diets of these animals are quite mysterious.

Paul Barrett: Sometimes, the last meal the dinosaur had would actually be fossilized with it, inside where its stomach would have been.

Barrett said paleontologists also study fossilized dinosaur droppings. In T. Rex droppings, for example, they’ve discovered the bones of a duck-billed dinosaur.

Paul Barrett: For example, in the case of a T. Rex, we see their teeth are very sharp and pointed, and ideally suited for slicing through meat and crunching through bone.

Identifying dinosaur diets from their teeth isn’t always so cut and dry, Barrett said. Sometimes fossils are misidentified.

Paul Barrett: Fossils from different dinosaurs have been mixed together, and the teeth from one dinosaur have been found with another dinosaur.

He said in one case, paleontologists unearthed a dinosaur believed to be a carnivore because it was found with carnivorous-looking teeth. But years later, it was discovered that those teeth belonged to another dinosaur, one which was preying on the aforementioned dinosaur, now known to be a plant-eater.

Some dinosaur diets still remain mysterious, according to Barrett.

Paul Barrett: A good example is the oviraptor, a dinosaur from Mongolia, which just has two tiny peg-like teeth on the roof of its mouth, but no other teeth at all. The diet of this animal has been debated an awful lot, over the past 50 to 60 years. Some people suggest it ate plants, other people think it ate fruit or seeds. Some people think it ate eggs, which is why it’s called oviraptor, which means ‘egg seizer’. Other people think it ate lizards or other small animals. Unfortunately, we’ve never, ever found a fossilized oviraptor with stomach contents inside, so we still have really, no idea what this particular dinosaur was eating.

Our thanks today to the Monsanto Fund – bridging the gap between people and their resources.

February 1, 2010

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