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What to Know About Dinosaur Diets

An expert answers students' questions about what dinosaurs ate and why.

  • Grades: 3–5, 6–8

The following questions were answered by dinosaur expert Don Lessem.

 

Q: Would a dinosaur eat us if it were alive today?
A: If dinosaurs were alive today, some would try to eat us, but most would be plant-eaters. I think we could outsmart the nasty ones and probably outrun most of them!

Q: The archaeopteryx had bird hips (right?) but it ate insects. Is it true that all bird-hipped dinosaurs were vegetarians and if so, what's the deal?
A: I'm not sure what the deal is either. Archaeopteryx was the first bird, descended from a dinosaur. What you eat doesn't make you one kind of animal or another.

Q: Do you think T. rex was a predator or a scavenger?
A: Both is more likely. Big carnivores today, from lions on down, are inefficient hunters and scavenge more often. Scavenging is more energy efficient. There were huge herds of triceratops and duckbills in T. rex's time, so plenty of ill, aged, young, and dead to feed upon without much dangerous and draining hunting effort. Dr. Jack Horner and I wrote a book all about T. rex, including this issue, for adults, called The Complete T. rex which I think your kids would like (Simon & Schuster). But I'm prejudiced. I wrote an article on this subject for Newsweek two years ago as well. I deal with the quality of Bakker's science, and the issues of extinction, warmbloodedness, and much of current dinosaur research in a book I wrote three years ago called Dinosaurs Rediscovered (Simon & Schuster). I hope you can find these.

Q: Were most dinosaurs plant-eaters or meat-eaters?
A: Most of the 335 kinds of dinosaurs ate plants, and about 100 kinds ate meat. But in any place, there were far greater numbers of plant-eaters than meat-eaters, just like today.

Q: Which dinosaurs were bigger — plant-eaters or meat-eaters?
A: Plant-eaters by far. T. rex and giganotosaurus, the biggest meat-eaters, were 7 or 8 tons and 45 feet long. The biggest plant eaters were 100 tons and 110 feet long!

Q: How many pounds of eggs did the oviraptor eat in a day?
A: We don't know how many pounds of eggs oviraptor ate, since it didn't leave a shopping receipt. Actually, we don't know if it even ate eggs. Its name means "egg eater," but it was given that name because it was found on top of a nest of eggs. Scientists back in the 1920s thought it was eating those eggs. We found out recently when more oviraptors were found, and one was straddling a nest of eggs, including an embryo, that that oviraptor was there because the eggs were its own babies that it was taking care of! Oviraptors have been found with lizard skeletons in their stomach openings. So they probably ate lizards more than eggs. How many lizards a day, I don't know.

Q: How do we know for sure which dinosaurs were plant-eaters and which were meat-eaters?
A: All four-legged dinosaurs were plant-eaters. Some two-legged ones were too. Beyond that, tooth shape is a good clue. Notched teeth were meat-eater teeth.

Q: How did brachiosaurus get so big by eating plants and not meat?
A: Plant-eaters got far bigger than meat-eaters maybe because they needed huge bellies to digest all that tough plant food. You can make a good diet from vegetables, you know.

Q: What kind of foods did the dinosaurs eat?
A: Most dinosaurs ate plants, just like most animals today. But some ate meat. We also guess that some ate insects and fruits. The plant-eaters ate ferns and herbs and leaves from trees. Conifer-tree needles have been found in the poop of duck-billed dinosaurs and around their stomach cavities, so they probably nibbled on evergreens.

Q: How much food could a T-Rex eat in a day?
A: We can't be sure. Big meat-eaters today like lions eat a lot at one time and then might not eat again for a week! T. rex could bite off 500 pounds in one bite! Maybe it ate a few hundred pounds of triceratops one day and then didn't eat again for a while. We'll never know.

Q: How did the dinosaurs eat? Why was the T. rex a carnivore?
A: Dinosaurs ate plants for the most part, because they were built to chew and grind plants with their teeth or rocks in their stomachs. Meat-eaters, like T. rex, had sharp, sawing teeth for cutting meat, so they ate other dinosaurs, either dead or alive.

Q: Were there omnivorous dinosaurs?
A: Probably, but we don't have any proof. We find plants in the poop and belly areas of some dinosaurs so we know that's what they ate, and lizards in the belly area of others and tooth marks on dinosaur bone to show us meat-eaters ate dinosaurs and reptiles. It's been speculated that small meat-eaters with varied teeth, like troodon, were built to eat a variety of foods. And toothless meat-eaters, such as the ostrich-like ornithomimids, may have eaten eggs, or fruits, or insects too. So odds are yes, but proof is lacking so far.

Q: Why did the sabertooth tiger want to eat the woolly mammoth?
A: Sabertooth tigers and woolly mammoths lived long after dinosaurs, so I'm no expert on them. Sabertooths were meat-eaters and so woolly mammoths might have been among their prey, I'd guess. Then again, woolly mammoths were so big that maybe sabertooths didn't risk going after them. Also, sabertooths had very narrow and long tusks. They might have been better equipped for scavenging — eating things already dead —  then hunting.

  • Part of Collection:
  • Subjects:
    Science, Archaeology and Anthropology, Archaeology, Dinosaurs, Paleontology and Fossils
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