Dino fright: meet South America's toughest dinosaur.(Cover story).

What do you get when you combine a bull's horns, T. rex's arms, and a shark's teeth? South America's scariest meat eater! It is called Carnotaurus sastrei (kahr-noh-TAWR-uhss SASS-tree-ee).

Paleontologists recently uncovered fossils, or remains, of what might have been a Carnotaurus. A paleontologist is a scientist who studies fossils. The bones, found in Brazil, may be only the second set of Carnotaurus fossils ever discovered. Brazil is a country in South America.

The tough dino lived about 115 million years ago. Its name means "flesh-eating bull." Carnotaurus had teeth like knives and a thick, powerful neck. Scientists say the dinosaur most likely ruled at the top of the food chain.

"Carnotaurus is a pretty amazing animal," paleontologist Mark Norell told WR News.

The 25-foot-long dinosaur was a type of abelisaur (ah-BEL-ih-sawr). Abelisaurs were large meat eaters. They roamed what is now South America during the Cretaceous (krih-TAY-shuhss) Period. That period lasted from 144 million to 65 million years ago. Carnotaurus's big horns helped it stand out among other abelisaurs. Its horns were 5 to 6 inches long.

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Studying Carnotaurus has not been easy. The only other Carnotaurus was found in 1984, in southern Argentina. That is a country in South America. Paleontologists say the fossils can do more than tell people about Carnotaurus. "[Fossils] tell us a lot about life on our planet," Norell says.

THINK ABOUT IT: What else might scientists want to know about Carnotaurus? Why?

Terrible Three

Carnotaurus ruled in South America, but other dinos were the boss up north. Hem's a look at some of North America's dinosaurs during the late Cretaceous Period.

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Albertosaurus (al-ber-toh-SAWR-uhss) This giant meat eater was 30 feet long and weighed more than 6,000 pounds. It had huge sawlike teeth.

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Tyrannosaurus (tuh-ra-nuh-SAWR-uhss) This dino was the largest dinosaur in North America. It could kill almost any animal in its path.

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Gorgosaurus (gohr-go-SAWR-uhss) Gorgosauruses might have hunted in packs. Paleontologists have found more than 20 skeletons of this dino.

TEACHING THE COVER STORY

Dino Fright

Scientists discover the fossils of South America's toughest dinosaur.

Before You Read

Ask students: What are fossils? What can scientists learn about dinosaurs from their fossils?

Vocabulary

abelisaur: a kind of large, meat-eating dinosaur that roamed what is now South America

Cretaceous Period: 144 million to 65 million years ago

fossils: remains

paleontologist: a scientist who studies fossils

Background

* How old are fossils? Remains must be at least 10,000 years old to be considered fossils. Scientists can estimate the age of a fossil by studying nearby rock layers.

* How do the Carnotaurus sastrei fossils in Brazil compare with the fossils found in Argentina?

The Argentinean fossils are more complete than the Brazilian fossils, but paleontologists found other remains with the fossils in Brazil. They uncovered the remains of two plant-eating dinosaurs, an ancient crocodile, and a freshwater turtle in the same area. An ancient fiver might have carried the remains to the spot, scientists say.

* What did Carnotaurus most likely eat? Paleontologists suspect that the dinosaur chowed down on plant-eating dinosaurs. Scientists aren't sure whether Carnotaurus actively hunted its food, scavenged already-dead dinosaurs, or both.

* Why didn't Carnotaurus roam North America? Scientists believe that the continents had split apart before Carnotaurus appeared. Before the dino's time, there were two continents, Laurasia and Gondwanaland. Laurasia contained North America. Abelisaurs roamed Gondwanaland, part of which later became South America.

Think Critically

What might Earth have been like during Carnotaurus's time?

Extend the Lesson

Create a diorama. Ask students to research more about the Cretaceous Period. Then have each student create a diorama showing some of the plants, dinosaurs, and other animals that lived during that time.

Web Resource

Learn more about different types of dinosaurs at www.amnh.org/ exhibitions/dinosaurs.

Source Citation
"Dino fright: meet South America's toughest dinosaur." WR News, Edition 3 [including Science Spin] 7 Nov. 2008: 3+. Educator's Reference Complete. Web. 17 Dec. 2009. .

Gale Document Number:A188997462