Open wide! What's in a tooth? Teeth contain mouthfuls of information about an animal.
Teeth--they help us chew our food and speak clearly, and they give us our dazzling smiles. Some animals use their teeth for other functions, such as fighting enemies or cutting down plants to build homes. But for scientists, teeth have another benefit: They tell secrets! A peek inside an animal's mouth can tell researchers everything from what the animal eats to how old it is.
When scientists dig for fossils of ancient animals, they often look for dental remains. Teeth last much longer than other bones, which can break down over time.
"Bones are porous, or have many tiny holes, while teeth are solid," explains Robert Feranec, a fossil expert at the New York State Museum in Albany, New York. This means that as bones become fossils, they can wear away more quickly than teeth.
Teeth also have an added layer of protection: a hard, white covering called enamel. Enamel is what helps keep teeth from chipping when you bite down on a nut or a crunchy chip. The substance is so hard that it can last for millions of years!
Why can finding an ancient tooth be so exciting for a scientist? One reason is that dental remains can help scientists identify the type of animal a group of bones came from. Each animal species has a unique set of teeth. They vary by number, size, shape, and organization. A crocodile, for example, has many sharp, pointed teeth that are spaced apart. A horse has large, flat teeth that are close together.
These differences give scientists clues to an animal's diet. Teeth come in different shapes in order to perform different jobs. "A carnivore's teeth are usually shaped into slicing blades," says Feranec. "Herbivores generally have square-shaped teeth that allow them to grind up plants or fruits." Omnivores, which eat both plants and meat, typically have both sharp and flat teeth.
Patterns on teeth can also hold information. When an animal chews its food, very small wear patterns develop on a tooth's surface. "Animals that eat grass will have lots of scratches on their teeth," says Feranec. "Animals that eat fruits or nuts or graze on leaves will have microscopic holes."
The Root of It All
By studying teeth, scientists can learn more about how an animal lived than just what made up its dinner. An ancient animal's diet gives clues about what its habitat was like. If an animal munched on parts of a tree, for example, it might have lived in a forest.
Since teeth grow and wear down at a steady rate over time, they can also reveal an animal's age and growth history. "Tooth enamel forms in daily layers, with distinct lines that can be counted, like tree rings," says Peter Ungar. He is an anthropologist who studies the teeth of modern-day and ancient animals. "Therefore, we know how long a tooth takes to form," he says. With these observations, scientists can figure out at what age an animal died.
Each of these clues can be fit together to tell scientists an animal's story. If, thousands of years from now, a scientist were to find one of your teeth, what kind of story would it tell about you?
Words to Know
Fossil--The hardened remains or traces of a living thing that died long ago.
Enamel--The hard, white substance covering the outer layer of teeth.
Carnivore--An animal that eats the flesh of other animals.
Herbivore--An animal that mostly eats plant matter such as leaves or seeds.
Omnivore--An animal that eats all kinds of food, both plants and other animals.
Herbivore: Plant-eaters like camels have a diet made up of tough, chewy plant foods, including grasses and grains. Large cutting teeth in the front bite through stems and leaves, while grinding teeth in the back mash them up.
Carnivore: Meat-eaters like tigers have teeth that are designed for killing and tearing. Large stabbing teeth called canines are used to catch and kill prey. Back teeth are shaped to shred through muscle and crack bones.
Omnivore: These animals, like chimpanzees, have a varied diet that includes plants and meat. As a result, they have more generalized teeth. Like carnivores, omnivores have canines, but they're much smaller. And, like herbivores, omnivores have grinding teeth too.
* Web Connection
For more on teeth and dental health, visit www.scholastic.com/supercience
CARING FOR YOUR TEETH
February is Dental Health Month! Some animals eat food that helps clean their teeth automatically. But humans need extra tools to maintain a sparkling smile.
Follow these simple tips to help keep your pearly whites healthy and strong.
* Brush your teeth at |east twice a day--after breakfast and before bed. If you can, brush after lunch and after eating snacks too.
* Brush your teeth for at least two minutes.
* Use a toothbrush with soft bristles, and replace it every three months.
* Floss at least once a day to get rid of the food and bacteria that a toothbrush can't reach.
* Avoid soda. It contains ingredients that can wear down tooth enamel.
Directions: Examine the teeth in each photo and identify each organism as an herbivore, a carnivore, or an omnivore.
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|Title Annotation:||life science|
|Article Type:||Cover story|
|Date:||Feb 1, 2010|
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