6 ALLOSAURUS ALLOSAURUS Range Allosaurus was a top predator during the Late Jurassic Period It is part of a group of meat-eating dinosaurs called theropods Allosaurus was very common in what is now North America Fossils that may be from Allosaurus have also been found in Portugal Tanzania Siberia and Australia Appearance Allosaurus could grow bigger than a school bus It looked like Tyrannosaurus But it was slightly smaller Allosaurus also had longer arms and small horns over its eyes It had sharp claws and long sharp teeth with serrated edges
Ferocious Predator Allosaurus could run very fast It ate plant-eaters including Camarasaurus and Stegosaurus Most likely it hunted alone It may also have been a scavenger This means it ate creatures that had recently died Triassic Period 252 million years ago When Did This Dinosaur Live Jurassic Period 201 million years ago Allosaurus fossil Length 39 to 43 feet 12 to 13 m 145 million years ago Weight 2.2 tons 2 metric tons Cretaceous Period 66 million years ago 7
8 AMARGASAURUS AMARGASAURUS Range Amargasaurus lived during the Early Cretaceous Period It roamed in the forests of what is now South America Only one fossil of this dinosaur has ever been found Appearance This plant-eater had two rows of long spines along its neck It was smaller than most of its sauropod cousins Its neck was shorter too But it was still a huge animal Triassic Period 252 million years ago When Did This Dinosaur Live Jurassic Period 201 million years ago Length E 39 feet 12 m Weight 9.9 tons 9 metric tons 145 million years ago Cretaceous Period 66 million years ago
9 Amargasaurus fossil Mysterious Spines Amargasaurus's spines puzzle dinosaur scientists They do not know what exactly the spines did The spines may have held up flaps of skin that looked like sails Or perhaps the dinosaur rattled the spines to make noise The sails or spines could have helped attract mates Or maybe they scared away predators
