(Die-NON-e-cuss)
Meat-eater
10 feet (3 meters) long
115-108 million years ago
Western North America

Until recently, scientists thought that dinosaurs were slow and sluggish, but clues left in Deinonychus fossils showed that many dinosaurs were active and agile. Dinosaurs like Deinonychus are the ancestors of modern birds! Deinonychus is named for the “terrible claw” on each hind leg.

(KOZ-mow-SERR-a-tops)
Plant-eater
15 feet (4.5 meters) long
76 million years ago
Utah, USA

Kosmoceratops had the fanciest head decorations of any dinosaur, with 15 horns and an elaborate frill around the neck. Perhaps these helped them to attract mates, or scare off the competition. Scientists still aren’t sure what Kosmoceratops did with such a showy head.

(MY-ah-SORE-ah)
Plant-eater
30 feet (9 meters) long
Late Cretaceous, 83-70 million years ago
Western North America

Maiasaura means “good mother dinosaur”. This duckbilled dinosaur earned its name because it was found with nests of eggs and youngsters. Maiasaura hatchlings grew very fast — up to 5 feet in one year! They were social animals and lived in large herds.

(PACK-ee-SEFF-a-low-sore-us)
Plant-eater
15 feet (4.5 meters) long
Late Cretaceous, 70-66 million years ago
Western North America

Pachycephalosaurus was the largest of the dome-headed dinosaurs. Its forehead was as thick as a bowling ball. Scientists study the fossilized domes and compare them to modern animals to figure out what they were used for. They may have used their heads to butt each other, like bighorn sheep.

(PAIR-ah-sore-oll-OH-fuss)
Plant-eater
30 feet (9 meters) long
Late Cretaceous, 76-74 million years ago
Western North America

What do you notice first about the Parasaurolophus? That unusual crest on its head was made up of bones with tubes. At first, scientists thought it might have been used like a snorkel, but now they think that it was used to make sounds, or show-off, or even cool-off. There’s still so much we don’t know about dinosaurs!

(TE-ro-sore)
Most were meat-eaters
Wingspans from 10 to 39 feet (3 to 12 meters)
Triassic to Cretaceous, 228-66 million years ago
World-wide

Pterosaurs (commonly known as pterodactyls) were winged reptiles. There were hundreds of different pterosaur species who could fly, glide, and also fold their wings to walk on four limbs. Pterosaurs were not dinosaurs, but they lived among them and ruled the skies for most of Mesozoic.

(ket-zel-KWAT-a-lus)
Meat-eater
35 feet (10 meter) wingspan
Late Cretaceous, 70-66 million years ago
Western North America

Quetzalcoatlus was the largest animal that ever flew (as far as we know)! Its wingspan was as wide as a fighter jet. Like many other pterosaurs it was lightly built, with a thin body, a long, pointed jaw, and sharp small teeth to catch its favored prey - fish. Engineers copied its body plan to design experimental aircraft. It is named for Quetzalcoatl — the feathered serpent god of the Aztec civilization.

(TRI-serr-oh-tops)
Plant-eater
30 feet (9 meters) long
Late Cretaceous, 68-66 million years ago
Western North America

Triceratops is named for its three long horns. Though the horns look scary, they were weak and not a good defense against T. rex. So, what did Triceratops use their horns for? Maybe they used them to attract or compete for mates but we still don’t know.

(Tuh-ran-oh-SORE-us rex)
Meat-eater
40 feet (12 meters) long
Late Cretaceous, 68-66 million years ago
Western North America

T. rex was one of the largest land-based carnivores of all time, and was the top predator in the ecosystem where it lived. Its massive skull contained 50 sharp teeth the size of bananas! We still don’t know for sure why this powerful animal had such small arms. That’s a mystery for future scientists to solve!

(YOU-tah-RAP-tore)
Meat-eater
20 feet (6 meters) long
Early Cretaceous, 130-125 million years ago
Western North America

Utahraptor is one of the largest and the earliest of the raptor dinosaurs. Although we haven’t yet found evidence of Utahraptor feathers, scientists believe that all the raptor-type dinosaurs had them. Most feathers were too delicate to leave any trace in the fossil record. The “velociraptors” in Jurassic Park should have been called Utahraptors, as the real Velociraptors were much smaller than their movie versions!