Coprolites, or fossil "poop", are one way that paleontologists (scientists who study ancient life other than humans) try to understand what dinosaurs and other fossil animals ate when they were living, but as you can imagine, it's not always so easy to tell who made the coprolites. One famous example of a coprolite that actually was attributed to a specific dinosaur (in this case, Tyrannosaurus Rex) was reported on by paleontologists, Dr. Karen Chin and colleagues, in the June 1998 issue of the scientific journal, Nature. This is truly a huge coprolite, weighing in at 17 inches (44 cm) long, 6 inches (15 cm) high, and 5 inches (13 cm) wide. The coprolite is dated at 65 million years of age and since T. Rex was the largest meat-eater around during that time (Late Cretaceous), the process of elimination suggests that this coprolite is T. Rex dung.

Other evidence that this coprolite,belonged to a meat-eater like T. Rex are the crushed up bone fragments that Dr. Chin found embedded in the coprolite. These shattered bone fragments tell us that T. Rex was capable of chewing its food (previously scientists thought food may have been dissolved in the stomach), and that T. Rex was feeding on Triceratops - some of the bone fragments are from the bony frill found at the back of the Triceratops skull. Amazing how many things you can learn about a dinosaur from its poop! Thanks for the great question.

You are right that scientists can tell something about what animals eat by looking at their teeth. Pointy, serrated or notched teeth are good for tearing flesh, while large, flat or extra-calcified teeth are good for grinding away at plants. Information about an animals diet can also be found by looking at their stomach contents and at their poop (no one said science was always fun!).

Scientists can also reconstruct entire skeletons from some fossils, and from this they can determine whether the animal was built more for plant eating (think giraffe and elephant body types) or for attacking prey (think cheetah and lion body types). List some things you think scientists might look for in terms of body design when they try to determine if dinosaur is a plant eater or a meat eater. You can use this info to guess what dinosaurs that you are unfamiliar with might have eaten, and then check to see if you were right!

From information on teeth, stomach contents, poop and body design, its pretty easy to tell apart animals that eat mostly meat (carnivores) from those that eat mostly plants (herbivores). However, many animals (omnivores) eat a mix of meat and plants, and may also supplement their diet with insects and eggs. (This is what humans do!) It would be harder to tell this from fossils, since it is not easy to identify insects and eggs after they'd been digested. Some scientists think that troodons were omnivorous since they have varied teeth.

Dinosaur skeletons are rare, but archeologists have found a few skeletons with teeth and a few with things inside their stomachs. For example, lizards have been found in the stomachs of some oviraptors. Fossil dinosaur poop has also been found. Conifer needles (think pine needles) have been found in the poop of duck-billed dinosaurs and in their stomachs. This evidence has been invaluable in determining what certain dinosaurs ate, and in developing general principals that can be applied to other types of dinosaurs for which we have less information. For example, scientists have decided that all four-legged dinosaurs were plant eaters. Does this mean that all two-legged dinosaurs were meat-eaters? Probably not. Sometimes we can get things wrong, too. When a fossil oviraptor was first discovered, it was lying on top of a pile of eggs, and it was assumed that this type of dinosaur ate eggs ("oviraptor" means "egg- eater"). After finding other oviraptor fossils on top of eggs and straddling nests, we now think that oviraptors laid eggs instead of eating them. I don't know much about dinosaurs, but I learned from the web site listed below that most of the different types of dinosaurs ate plants, but about a third ate meat. If you had to make a quick guess, would you think this was true about animals alive today?

For more information about dinosaurs go to
dinosaur

or

Dinosauria